Inhoudsopgave
Abstract 3
Introduction 4
1.1. Bipolar disorder 4
1.1.1. (Hypo)manic episode 5
1.1.2. Major depressive episode 6
1.1.3. Mixed episode 6
1.1.4. Epidemiology and course 7
1.2. BD misdiagnosis and borderline personality disorder 8
1.3. Similarities and differences between BD and BPD 9
1.4. Personality Five Factor Model 10
1.5. Research questions and hypotheses 12
Method 14 2.1. BD respondents 14 2.2. BPD respondents 15 2.3. Instruments 15 2.3.1. Mood symptoms 16 2.3.2. Personality traits 16
2.3.3. Personality states: severity of personality problems 17
2.4. Data-analysis 17
Results 19
3.1. Respondents 19
3.2. Correlations 20
3.3. Comparison of personality traits between BD and BPD 20 3.4. Comparison of personality states between BD and BPD 21
Discussion 23
4.1. Personality traits in BD and BPD 23
4.2. Personality states in BD and BPD 24
4.3. Mood state 25 4.4. Implications 26 4.5. Limitations 28 4.6. Future research 29 Conclusion 30 References 31
Abstract
Bipolar disorder (BD) is a common mood disorder clinically characterized by mood instability. This and other phenomenological features are shared by borderline personality disorder (BPD). Because of the different treatment implications, it is important to distinguish BD from BPD. The aim of this study is to identify similarities and differences in underlying personality traits and states as a possible cause for this symptomatic overlap. An exploratory observational study was conducted as part of a larger cohort study (BINCO). Patients were included if they were recently diagnosed with BD and were about to start with their treatment. The NEO-FFI and SIPP-SF were used as traits and state scales, the YMRS and QIDS-SR-NL were used to specify the patient’s mood state. Results of patients with BPD on SIPP-SF were used from Routine Outcome Monitoring (ROM) baseline measurements. Results on NEO-FFI were compared based on population norm scores and previous research. BD patients
compared to BPD patients showed lower scores on agreeableness, and higher scores on extraversion. BD patients experience fewer problems regarding social concordance than BPD patients. Remarkably, mean scores indicated that BD patients experience more problems regarding their identity than BPD patients. Mood state influenced scores of BD patients on different trait and state scales to some extent. The findings of this study, especially regarding the identity problems of BD patients, could contribute to more custom-made therapy. The similarities and differences found are promising and should be explored further within the longitudinal prospective (BINCO) study.
Introduction
“Time will pass; this mood will pass; and I will, eventually, be myself again. But then, at some unknown time, the electrifying carnival will come back into my mind.” (Jamison, 1996, p.188).
An individual’s state of mind colours many aspects of one’s thoughts, view of the world and behaviour (Gray & Bjorklund, 2014, p. 638). Every individual experiences fluctuations in their feelings and moods. Mood can be described as a continuum; a person may feel more joyful or sad during one day than during another. However, in some individuals these changes in mood can be very extreme. They may become so intense and prolonged that they can lead to severe impairments. Both bipolar disorder (BD) and borderline personality disorder (BPD) are clinically characterized by mood instability. Although BD and BPD are different disorders, they share other phenomenological features as well such as impulsivity and interpersonal difficulties. The aim of this study is to identify similarities and differences in underlying personality traits and states as a possible cause for this symptomatic overlap of the two disorders.
1.1. Bipolar disorder
BD, also known as manic-depressive illness, is a common mood disorder characterized by recurrent episodes of depression and mood elevation (mania or hypomania) (Phillips & Kupfer, 2013). Although mania and severe depression (melancholia) have been described as distinct conditions for ages (Angst & Marneros, 2001), the unique aspect of BD is the occurrence of both psychiatric conditions in the same person over time.
The origin of BD lies in the work of Greek physicians (c. 400 BC) who established mania and melancholia as two of the earliest diseases (Angst & Marneros, 2001). Aretaeus of Cappadocia (AD 150) was the first who connected mania with melancholia in the same person (Baldessarini & Tondo, 2001). It wasn’t until the mid 19th century that this connection was further described (Healy, 2010). Jean-Pierre Falret described, in 1854, la folie
circulaire, the circular reoccurrence of both manic and depressive mood episodes (DeRubeis,
Strunk & Lorenzo-Luaces, 2016). His description was similar to the modern concept of BD. Emil Kraepelin later proposed in 1896 a more systematic and comprehensive description of manic-depressive insanity based on observations of many patients with recurrent melancholic and manic episodes (Angst & Marneros, 2001). His contribution to understanding manic
depressive illness was enormous. However, his call for unification of all mood disorders within the concept of manic-depressive insanity was disputed. Kraeplin’s view was challenged by Wernicke (1906). He made a very important distinction between unipolar and bipolar disorders. Although this distinction remained mostly unrecognized until the 1960s, it is now the basis for the currently used diagnostic classification systems (Kupka, Knoppert-van der Klein & Nolen, 2008).
BD was first introduced and conceptualized according to valid and reliable criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM) III (Yutzy, Woofter, Abbott, Melhem, & Parish, 2012). In later versions of the DSM the definition of BD has developed into a more nuanced subtype system.
The DSM-IV-TR describes different types of BD: bipolar I disorder (at least one manic or mixed episode), bipolar II disorder (at least one episode of hypomania in addition to an episode of major depression, but without any history of mania), cyclothymic disorder (a history for at least 2 years of several hypomanic episodes and depressive episodes, but no major depressive episodes), and bipolar disorder not otherwise specified (bipolar features are present, but they do not meet the criteria for any specific disorder) (American Psychiatric Association, 2000).
1.1.1. (Hypo)manic episode
A manic episode is characterized by a distinct period of abnormal and persistent elevated, expansive or irritable mood (American Psychiatric Association, 2000). Important key elements are an increase in energy, psychomotor agitation, an inflated self-esteem, and little need for sleep. BD patients are more talkative, experience racing thoughts which are difficult to stop, are easily distracted and are often impulsive. Their impulsivity may lead to activities that have a high chance of problematic consequences (buying sprees, sexual indiscretions, or unwise investments). Some BD patients may become delusional or experience hallucinations. Frequently, BD patients lack insight into their disorder and consequently often do not believe that they need help or treatment.
A person is diagnosed with a manic episode if they experience at least three manic symptoms for at least a week (or shorter if hospitalization is necessary), and the disturbance caused by the symptoms must cause significant impairments in daily functioning. Manic-like symptoms that are caused by physiological effects of a substance or treatment are not considered to be manic symptoms as part of BD (American Psychiatric Association, 2000).
A hypomanic episode differs from a manic episode in several ways (Gilbert, 2013). The elevated mood only needs to last for four days, symptoms are milder and not psychotic, hospitalization as a result of mood state is not necessary, and there is no marked impairment in functioning (American Psychiatric Association, 2000). During a hypomanic episode, an outsider may not even recognize that a problem exists (Gilbert, 2013). However, someone closer to the BD patient is able to recognize the behaviour as distinct from the characteristic or usual functioning of the person.
1.1.2. Major depressive episode
In addition, to receive a diagnosis of BD, at least one major depressive episode must have occurred besides a manic or hypomanic episode (American Psychiatric Association, 2000). A major depressive episode is characterized by both physical and mental symptoms. At least one of these symptoms is either a depressed mood or a loss of interest or pleasure. There may be a significant weight loss or weight gain, a decrease or increase in appetite, insomnia or hypersomnia, psychomotor agitation or retardation, loss of energy, feelings of worthlessness, diminished ability to concentrate or think, indecisiveness, and recurrent thoughts of death or suicidal ideation. These symptoms occur for most of the day, nearly every day, for at least a 14-day period, and they cause marked distress or impairment in important areas of daily functioning. A patient is diagnosed with a major depressive episode if the symptoms are not due to bereavement or physiological effects of a substance or a physical disease.
1.1.3. Mixed episode
Besides a (hypo)manic or major depressive episode, some BD patients experience mixed episodes. During a mixed episode, a patient experiences manic and depressive symptoms simultaneously or in rapid succession (DeRubeis et al., 2016). During one week, a patient must experience the criteria for both a manic and a depressive episode. Since this criterion is very strict, few patients are diagnosed with a mixed episode (Jabben & Arts, 2011). The recently released DSM-5 attempts to acknowledge the existence of dimensional mixed states, by including the mixed specifier (Hu, Mansur & McIntyre, 2014). With the inclusion of a mixed features specifier, the DSM-5 tries to take into consideration the existence of subsyndromal mixed states and capture a large proportion of patients with these kinds of symptoms.
1.1.4. Epidemiology and course
The lifetime prevalence of BD is approximately 1%. Although this prevalence is lower compared to other psychiatric disorders such as major depressive disorder (± 20%), or anxiety disorders (± 30%), it is a serious condition. This is illustrated by the fact that BD causes relatively more functional and social impairments, and a greater reduction in quality of life (Phillips & Kupfer, 2013), making it a leading cause of disability worldwide (World Health Organization, 2016). BD is associated with a higher prevalence of several medical conditions and suicide, both causing premature death (Crump, Sundquist, Winkleby & Sundquist, 2013). Estimates of suicide attempts by individuals diagnosed with BD range between 25-50% (Gilbert, 2013). If the burden on family and friends, and the economic impact are taken into consideration, the public health impact is enormous (Conus, Macneil & McGorry, 2014; Gilbert, 2013).
Although unipolar major depressive disorder has a higher prevalence rate in women, BD is approximately equally prevalent in men and women (Jabben & Arts, 2011). Women tend to have more depressive and mixed episodes than men, and a higher chance of the rapid cycling pattern (Solomon et al., 2010). The rapid cycling pattern is diagnosed if a patient has experienced at least four manic episodes in the last twelve months (American Psychiatric Association, 2000). Men are more likely to experience mania, have either a depressive of manic episode at an earlier age, and experience lengthier episodes (Gilbert, 2013).
Research has shown that the predisposition for BD is strongly heritable (Johnson, Cuellar & Miller, 2009). BD typically emerges in late adolescence or young adulthood (DeRubeis et al., 2016), usually around the age of fifteen to thirty (Jabben & Arts, 2011). The likelihood of an early onset of BD increases if individuals have a familial history of BD, and is often associated with a more severe disease course, more mood episodes, psychotic symptoms, and comorbid anxiety disorders and substance abuse (Goodwin & Jamison, 2007). The likelihood of developing BD decreases with age (DeRubeis et al., 2016).
The course and severity of BD are variable. Some patients experience only a few mood episodes in their lives and function well between them, others experience episodes more frequently and are not symptom free in between (Jabben & Arts, 2011). High proportions of patients initially diagnosed with a manic episode encounter a new episode later in life (Tohen et al., 2003). The frequency of manic and depressive episodes in the past predict more episodes in the future course of BD. The presence of residual mood symptoms after initial recovery is associated with a higher risk of recurrence of mood episodes, a higher number of lifetime mood episodes, and psychiatric comorbidity (Perlis et al., 2006). After
they have been diagnosed with BD, patients will experience on average four mood episodes in the following ten years (Solomon et al., 2010).
Manic episodes usually have a shorter duration than depressive episodes (Beyer, 2008). The same applies to recovery after a manic episode. Remission after an acute manic episode takes three weeks in approximately 40 to 50% of the patients, and twelve weeks in 70 to 80%. Remission percentages are less favourable regarding acute depressive episodes (30 to 50%). Within two years after a severe episode, 90% of the patients reach symptomatic recovery, while only 30% attain full functional recovery (Tohen et al., 2000).
1.2. BD misdiagnosis and borderline personality disorder
Only 20% of the patients with BD are diagnosed within the first year of seeking treatment (Grande, Berk, Birmaher & Vieta, 2016). Patients are often first assigned a differential diagnosis. The most common differential diagnosis is major depressive disorder, but personality disorders are also common, especially BPD (Grande et al., 2016).
BPD is a serious mental disorder. The disorder is characterized by a pervasive pattern of instability in a variety of contexts, including affect regulation, impulse control, self-image, and interpersonal relationships beginning in early adulthood (American Psychiatric Association, 2000). Key features of the disorder include repeated self-injury, suicidal tendencies, and emotional dysregulation (Lieb, Zanarini, Schmahl, Linehan & Bohus, 2004). BPD is diagnosed if five or more of the following characteristics of the disorder are present: frantic efforts to avoid real or imagined abandonment, a pattern of unstable and intense interpersonal relationships characterized by alternation between extremes of idealization and devaluation, markedly unstable self-image, impulsivity that is potentially self-damaging, recurrent suicidal behaviour, affective instability, chronic feelings of emptiness, difficulty to control anger, and paranoid or dissociative symptoms (American Psychiatric Association, 2000). Profound instability is the hallmark feature of BPD. Emmelkamp and Kamphuis (2007) state what seems stable about BPD is its instability.
BPD impairs an individual’s self-perception, motivation, social interaction and relationships, and causes significant distress and disability (Gray & Bjorklund, 2014; Zimmerman, 2010). Prevalence estimates of BPD for the general population are between 1 and 2% (Emmelkamp & Kamphuis, 2007). The prevalence distribution across men and women is equal. Up to 10% of the BPD patients end up committing suicide, which makes BPD just as BD, one of the risk diagnoses for suicide.
Although BD and BPD are different conditions, they share phenomenological features (Zimmerman, 2010). For instance, mood instability and impulsivity are core features of both disorders (Antoniadis, Samakouri & Livaditis, 2012; Zimmerman, 2010), as well as problematic interpersonal functioning, and suicide attempts (Ruggero, Zimmerman, Chelminski & Young, 2010). Overlapping symptoms make differentiating BD from BPD challenging (Ghouse, Sanches, Zunta-Soares, Swann & Soares, 2013).
The symptomatic overlap between the disorders raised the question as to whether they belonged to the same spectrum (Reich, Zanarini & Fitzmaurice, 2012). Some researchers (Akiskal, 2004; Wilson et al., 2007) stated that cases of BPD are part of the bipolar spectrum and therefore the two conditions would be expressions of the same underlying disorder. Up to now this view has not been supported by current research (Ghouse et al., 2013). However, the relationship between BPD and BD remains the subject of controversy (Zimmerman et al., 2010). Many researchers have found BD to be underdiagnosed (Ghaemi, Dalley, Catania, & Barroilhet, 2014). They assert that, due to symptomatic overlap, BD patients are wrongly diagnosed with BPD. This misdiagnosing has severe clinical implications, such as the underprescription of mood stabilizing medication, and risk of more severe recurrence of mood episodes (Zimmerman, Martinez, Young, Chelminski & Dalrymple, 2014).
1.3. Similarities and differences between BD and BPD
Several studies reviewed the similarities and differences between BD and BPD extensively. The cause of misdiagnosing BD as BPD is mainly sought in failing diagnostic sensitivity or accuracy (Barroilhet, Vöhringer & Ghaemi, 2013; Gilbert, 2013; Phelps & Ghaemi, 2012; Wilson et al., 2007), or in comorbidity of the two disorders (Zimmerman, 2010). Approximately 10% of the patients with BPD are diagnosed with BD (Fornaro et al., 2016; Paris, Gunderson & Weinberg., 2007). The same percentage applies for patients with BD and comorbid BPD. However, since the occurrence of a combination of the two disorders is rather rare (Zimmerman, 2010), it seems unlikely that comorbidity explains the confusion in diagnosing BD.
Antoniadis et al. (2012) reviewed similarities and differences in order to study common etiological factors of BD and BPD which might explain diagnostic confusion between the two conditions. They found that the two disorders share general phenotypic dimensions, such as affective instability and impulsivity, which may account for the diagnostic overlap. Similar functional and structural neuroanatomical abnormalities between
the two disorders were found as well. Frías, Baltasar and Birmaher (2016) proposed cognitive features of BD and BPD, besides mood or affective symptoms, to help differentiate BD from BPD. However, their results were inconclusive. Possible common underlying personality traits or characteristics as a confounder were not studied. This might be important, since underlying similarities in personality factors may cause the overlap in manifestations of the disorders (Smith, Muir & Blackwood, 2004). Since personality characteristics can be affected and become more extreme during mood states (Barnett et al., 2011; Kupka et al., 2008), an incorrect diagnosis might be more likely during episodes of (hypo)mania or depression. For instance, irritability during a (hypo)manic episode of BD could be confused with difficulties controlling anger seen in BPD (Ruggero et al., 2010). In addition, personality can be seen as a predisposing and precipitating factor in the development of BD or BPD (Kupka et al., 2008). It is possible that similar personality profiles or traits are shared by both BD and BPD patients.
Little research has been done regarding personality factors as a possible underlying cause for the diagnostic confusion. Henry et al. (2001) compared different personality traits to determine whether there is a dimensional overlap between the disorders. The study compared impulsivity, affective liability and intensity, in patients with BD II and BPD patients. Affective lability appeared to be a common trait for both BPD and BD. However, there was a proportion of 46% of comorbidity for these two diagnoses in their sample. The same applies for other studies that compared the two disorders; patients showed co-occurrence of the two disorders (Ghaemi et al., 2014; Paris et al., 2007). Adequate distinctions between the two disorders cannot be made in these studies.
1.4. Personality Five Factor Model
Other studies (Kotov, Gamez, Schmidt & Watson, 2010; Paris et al., 2007) have assessed the personality of patients with mood disorders using the Five Factor Model (FFM). The FFM is based on the trait theory (Digman, 1990; Verheul et al., 2008), and is one of the most universal and comprehensive taxonomies for describing personality, which can be used cross-culturally for both the general and clinical population. According to the FFM, personality is a relatively unchangeable entity and personality traits are distinguished from more variable personality states (Andrea et al., 2007). Personality traits are viewed as enduring patterns of thoughts, feelings, and behaviour, whereas personality states are considered to be characteristic adaptations to the environment, including coping strategies, acquired skills and
self-concepts (Martin, Long & Poon, 2002). Personality states are more pronounced by their changeability, and are variable intra-individual over time, compared to traits.
The FFM organizes personality traits in terms of five dimensions: extraversion, agreeableness, conscientiousness, neuroticism, and openness to experience. Extraversion refers to the tendency to experience positive emotions, prefer frequent interpersonal interactions, be energized and to seek excitement (DeRubeis et al., 2016; Gray & Bjorklund, 2014). High scores on the dimension agreeableness represent characteristics such as sympathy, altruism, caring, and emotional support at the one end of the dimension, and hostility, indifference to others, self-centeredness, spitefulness, and jealousy at the other (Digman, 1990). Conscientiousness refers to the control of own behaviour with regard of certain goals (Gray & Bjorklund, 2014), and is associated with characteristics such as ordered, dutiful, achievement-striving, and self-disciplined. Neuroticism refers to emotional instability and the tendency to experience distress (DeRubeis et al., 2016). High neuroticism scores represent chronic negative affect which is often associated with irrational thinking, low self-esteem, poor control of impulses, and ineffective coping (Digman, 1990). Openness to experience refers to seeking out new experiences and having a fluid style of thought (Gray & Bjorklund, 2014).
A meta-analysis by Malouff, Thornsteinsson and Schutte (2005) showed that the FFM can be used to determine a certain profile, associated with different clinical disorders. Various clinical disorders are associated with a profile of high neuroticism scores and low conscientiousness, agreeableness and extraversion scores (Malouff et al., 2005). Also patients suffering from mood disorders exhibit higher levels of neuroticism and lower levels of conscientiousness. According to DeRubeis et al. (2016) the personality dimensions most associated with mood disorders are neuroticism and extraversion. Barnett et al. (2011) dissected state and trait associations between manic and depressive episodes in BD patients, and their personality. They found clear mood state effects on self-reported personality. Depressive symptoms were associated with low extraversion and elevated neuroticism, whereas manic and hypomanic symptoms were associated with increased extraversion. Kim, Lim, Kim and Joo (2012) and Kotov et al. (2010) found similar results regarding neuroticism and extraversion.
The FFM has been used as well to establish personality domains of BPD. A study by Henriques‐Calado, Duarte‐Silva, Junqueira, Sacoto and Keong (2014) shows high neuroticism to be the characteristic of most personality disorders and a primary marker for the degree of a
personality dysfunction. Higher levels of neuroticism have indeed been found in patients with BPD, together with low levels of agreeableness (Morey & Zanarini, 2000).
Although personality traits have been closely assessed in both BD and BPD separately (Bayes, Parker & Fletcher, 2014), no research has been done on a combined comparison of both disorders regarding personality traits (Arnevik et al., 2009). In addition, little is known regarding personality states in both patient groups and comparisons of these groups. Personality states can be established using the Severity Indices of Personality Problems (SIPP), a dimensional measure of personality functioning (Verheul et al., 2008). The SIPP establishes personality states on five different domains: self-control, identity integration, responsibility, relational capacities, and social concordance.
Since misdiagnosis between BD and BPD occurs, and both disorders have symptomatic overlap, there might be similarity in the personality profiles as well. Although research has been done, the relationship between BD and BPD regarding personality is still unclear (Benazzi, 2008; Paris et al., 2007; Ruggero et al., 2010; Zimmerman & Morgan, 2013), comparing personality profiles of the two disorders could make the differences and similarities between the two disorders clearer.
Because of the different treatment implications, it is important to distinguish BD from BPD (Zimmerman & Morgan, 2013). Incorrect diagnoses lead to insufficient treatment, and an adverse course of the disorders (Yutze et al., 2012; Conus et al., 2014). This may result in patients receiving treatment that is unnecessary or contraindicated. Considering the high burden, the progressive course of BD, the high rate of suicide attempts, and the significant impairments, it is important that bipolar patients receive proper treatment. Diagnosing the disorder is the first step towards treatment and recovery. Any delay hinders this process (Yutzy et al., 2012; Knežević & Nedić, 2013). Unfortunately, the recognition of BD often takes considerable time. Moreover, insight in personality states and traits of BD patients can contribute to the development of more effective treatment for BD.
1.5. Research questions and hypotheses
This study explores the personality profiles of patients who were recently diagnosed with BD, compared to patients with BPD. The aim of the study is to answer the following research question: what are the differences and similarities in personality profiles between BD patients and BPD patients? Personality profiles will be based on both trait and state scales.
Since BD is a mood disorder, it is expected that similar results to those of Kotov et al. (2010) will be found in BD patients regarding high levels of neuroticism, and low levels of conscientiousness. Considering the periods of elevated mood that occur in bipolar patients, an association is expected between BD and higher levels of openness to experience and extraversion. It is hypothesized that similar scores will be found for BPD on these trait scales of the FFM, considering the overlapping features of BD and BPD (Malhi & Berk, 2014; Morey & Zanarini, 2000).
Considering the overlap of both disorders on features such as interpersonal difficulties and impulsivity (Antoniadis et al., 2012; Ruggero et al., 2010; Zimmerman, 2010) scores on state scales regarding personality domains such as relational capacities, social functioning and self-control are expected to be low for both disorders. It is expected that BPD patients will exhibit more identity problems, considering that their unstable self-image is a particular characteristic of BPD. Age and gender seem to be important confounders to take into account (Barnett et al., 2011; Henriques-Calado et al., 2014). Finally, it is hypothesized that mood states of BD patients are associated with scores on the different trait and state scales (Barnett et al., 2011).
Method
This exploratory observational study was part of a larger cohort study, the Bipolar Netherlands Cohort (BINCO) study. The BINCO study is a naturalistic, longitudinal study that started in July 2016. Respondents will be followed during one year, and this will be extended during the coming years. The expectation is that 200 patients will be included in the coming four years. The BINCO study is aimed at studying the long-term prognosis of BD, identifying biological markers that are associated with the disorder, exploring stress, trauma, and lifestyle factors associated with the outcome of the disorder, and determining the disease course and treatment response. Biological sampling is an important focus of the BINCO study. However, the current study focused on the personality factors in relation to the disease.
2.1. BD respondents
The patients who were included in this study are those who were recently diagnosed with BD based on the DSM-IV-TR and were about to start with their treatment at the outpatient facilities PsyQ (Rotterdam and The Hague), or Rivierduinen (Leiden), or were patients who were admitted because of their first manic episode. Patients were excluded if they were diagnosed with BD not otherwise specified or cyclothymic disorder, if they were younger than eighteen years old, if they could not read, speak, or understand Dutch, or if they had already been treated for BD in the past.
Patients were informed about the study by their clinician. They were provided with an information folder, and asked if they wished to participate. Participation was voluntary and anonymous. If a patient was interested in participating, the research nurse contacted the patient, and made an appointment with the patient for the baseline measurement. The baseline measurement took place at the research facility or at the patient’s home. During this appointment the patient underwent a psychiatric interview, and blood, faeces, saliva and hair samples were taken. Patients were informed at the beginning of the interview about the confidentiality of the measurements, the issue of written consent, and the fact that the interview would be recorded on tape. All patients gave their consent and none objected to the recording of the interviews. The baseline measurement lasted on average two hours. In case of impairment of decision skills due to the disorder, not only the patient but also a family member was asked for permission. Informed consent from the patient to use the data and samples was requested after recovery. All the collected data is confidential. If the patient
refused, the collected data was destroyed. The study has been approved by the Medical Ethics Committee.
2.2. BPD respondents
To compare personality state profiles of BD patients with those of BPD patients, results of patients with BPD were used from Routine Outcome Monitoring (ROM) baseline measurements at the outpatient clinic PsyQ Rotterdam. This data was obtained between March 2013 and October 2016 from 649 BPD patients. Of these patients, 556 were excluded because they either met criteria for an Axis I disorder and/or were diagnosed with a comorbid Axis II disorder. From the 93 remaining BPD patients, eleven were matched on the basis of age and gender to the BD patients (N = 11) that were included in the study.
2.3. Instruments
A confirmation letter was sent to the respondent after the appointment for the baseline measurement had been made, and the respondent received a link to an online self-report questionnaire in Qualtrics (2016 Qualtrics, LLC). The link was sent one week before the appointment took place. The questionnaire consisted of different measurement instruments; The Trauma Screening Questionnaire (TSQ), Perceived Stress Scale (PSS), Irritability Scale (IS), World Health Organization Disability Assessment Scale (WHODAS), NEO Five Factor Inventory (NEO-FFI), Severity Indices of Personality Problems-Short Form (SIPP-SF), Behavioral Inhibition and Approach Scale (BIS/BAS scale), and the Food Frequency Questionnaire (FFQ). These questionnaires were an important part of the baseline measurement. The completion of the online questionnaire took between 45 and 60 minutes. The results on the baseline measurements of the self-report questionnaires NEO-FFI and SIPP-SF were used for this study. Background information (e.g. illness history) and demographic variables were assessed using the Client Registration Form (CRF). The Young Mania Rating Scale (YMRS) and Quick Inventory of Depression Symptomatology Self Report (QIDS-SR-NL) were used at the end of the baseline interview to specify the patient’s mood state.
2.3.1. Mood symptoms
The YMRS is a 11-item rating scale used to evaluate manic symptoms. Each item is given a severity rating on a 0 - 8 or 0 - 4 scale. The scale is filled out by a clinician and based on the patient’s report of his or her clinical condition over the previous 48 hours, and upon clinical observations made during the course of the baseline interview (Young, Biggs, Ziegler & Meyer, 1978). Scores between 0 - 8 indicate no manic symptoms, scores between 13 - 20 indicate mild manic symptoms, and scores between 26 – 38 (and higher) indicate severe manic symptoms. It takes five minutes to complete the YMRS.
The QIDS-SR-NL is a 16-item self-report questionnaire, designed to assess the severity of depressive symptoms (Rush et al., 2003). Each item is rated between 0 - 3, that best describes the patient over the last seven days. The total score ranges from 0 to 27, and is obtained by converting the responses on the items into the nine DSM-IV-TR symptom criterion domains. Total scores between 0 - 5 do not indicate a depression, 6 - 10 indicate mild depression, 11 - 15 indicate moderate depression, scores between 16 - 20 indicate severe depression, and 21 - 27 indicate very severe depression. It takes 5 to 7 minutes to complete the QIDS-SR-NL.
2.3.2. Personality traits
The NEO-FFI consists of 60 items, with each item rated on a five-point Likert scale (1 = strongly disagree, and 5 = strongly agree). Each of five personality dimensions (neuroticism, extraversion, conscientiousness, openness to experience, and agreeableness) are assessed by means of a group of twelve items. Internal consistency, measured in a healthy population (N = 1000), ranges from = 0.68 to = 0.86, acceptable for research purposes (Costa & McCrea, 1992).
The NEO-FFI will be used to identify the different personality traits that characterize BD. Since BPD patients are not included in the BINCO study and NEO-FFI is not part of the ROM baseline measurement, the results of BPD patients on the NEO-FFI cannot be directly measured or identified. Therefore, the data of BD patients will be compared with normative data based on the NEO-FFI manual by Costa and McCrea (1992) and existing research by Morey and Zanarini (2000) regarding the scores of BPD patients on the NEO-FFI. Morey and Zanarini (2000) studied the relationship between the FFM and BPD using the NEO-FFI. They included 362 inpatients with BPD at the McLean Hospital in Belmont. Patients were between 18-35 years old (M = 26.9, SD = 5.8), and had no history or current symptoms of a serious
organic condition, schizophrenia, or BD I. Most of the patients were female (80.3%). Semi-structured interviews were administered to determine a BPD diagnosis (n = 279).
2.3.3. Personality states: severity of personality problems
The SIPP-SF will be used to assess the core components of (mal)adaptive personality functioning of bipolar patients. The SIPP-SF is a 60-item questionnaire derived from the SIPP-118 (Verheul et al., 2008). Each item is rated on a four-point Likert scale (1 = strongly disagree, and 4 = strongly agree). Five domains are included which capture different facets of personality functioning (De Viersprong, n.d.): social concordance (the ability to regulate aggression and frustration, and to work constructively and respectfully with others), relational capacities (the capacity to love and to feel recognized in order to maintain long-term, intimate relationships), self-control (the capacity to tolerate and control emotions, to focus concentration and direct impulses), responsibility (trustworthiness, and the ability to set and achieve goals in line with social values and norms) and identity integration (self-respect, stable self-image, purposefulness, enjoyment, and an understanding of internal and external events). The domains are assessed using groups of twelve items. Internal consistency measured in a healthy population (N = 478) ranges from = 0.65 to = 0.83 (Verheul et al., 2008, and ranges in an adolescent clinical population (N = 378) from = .62 to = .89 (Feenstra, Hutsebaut, Verheul & Busschbach, 2011). Higher scores on a domain imply more adaptive functioning (Rossi, Debast & Van Alphen, 2016). Scores lower than 40 indicate impaired adaptive functioning (De Viersprong, n.d).
2.4. Data-analysis
IBM SPSS Statistics 23.0 was used for data-analysis. Demographic and background characteristics were determined using descriptive statistics. Pearson correlations were calculated to determine associations between mood state (QIDS, YMRS) and scores on personality traits and problems (NEO-FFI, SIPP-SF). The personality profile of BD patients according to the NEO-FFI was analysed by means of frequencies and descriptive statistics. One sample t-tests were used to test the differences between BD patients and BPD patients on the subscales of the NEO-FFI, and to compare the scores of BD patients with healthy
population norm scores (Costa & McCrae, 1992). No total test scores were computed for the NEO-FFI and SIPP-SF in view of the assumption of uncorrelated subscales (Costa & McCrae, 1992; De Viersprong, n.d.). To test the differences between the BD and BPD patients on the
different domains of the SIPP-SF, ANOVA was used with all subscales in one model (instead of multiple t-tests) to control for type I error. To control for the possible confounders age and gender, each patient with BD was matched using case-control matching with the fuzzy extension, to a BPD patient by age and gender. Since the samples were matched on age and gender, these variables were not used as co-variates. Statistical significance was tested at the level of p < 0.05 regarding all analyses.
Results
Between the start of the BINCO study in July 2016 and the data-analysis for the current study in November 2016 twelve patients participated in this study. Of these patients, eleven filled in the online self-report questionnaire.
3.1. Respondents
Basic clinical and demographic characteristics are summarized in Table 3.1. The included patients were all Dutch. They had a mean age of 32.6 years (SD = 9.3). The majority of the patients was female (n = 8, 63.6%), unmarried (n = 8, 63.6%), and reported a family history of depression (n = 8, 63.6%). Only three patients (27.3%) reported a family history of BD. All patients received another diagnosis preceding the BD diagnosis. This was mostly depression (n = 3, 27.3%), and ADHD (n = 3, 27.3%). None of the BD patients had previously received a diagnosis of a personality disorder.
All patients reported they had received mental health care treatment. A total of ten patients (90.9%) reported they had received outpatient treatment before being diagnosed with BD. Two patients (18.2%) had been clinically admitted in the past.
Scores of BD patients on the YMRS and QIDS-SR-NL are shown in Table 3.1 as well. Scores of patients on the QIDS-SR-NL indicated no depression to severe depression (min. = 3.0 - max. = 18.0). No manic symptoms to mild manic symptoms were indicated by the YMRS (min. = 0.0 - max. = 16.0).
Table 3.1. Sociodemographic and clinical characteristics of the BD patients (N = 11).
Patient characteristics Gender Female n (%) 8 (63.6) Male n (%) 4 (36.4) Age Mean (SD) 32.6 (9.3) Diagnostic history Depression n (%) 3 (27.3) Burn-out n (%) 2 (18.2) ADHD n (%) 3 (27.3) Eating disorder n (%) 1 (9.1) Anxiety disorder n (%) 1 (9.1) Personality disorder n (%) 0 (0) Previous treatment Outpatient n (%) 10 (90.9) Clinical n (%) 2 (18.2) QIDS Mean (SD) 9.3 (5.1) YMRS Mean (SD) 5.3(5.4)
3.2. Correlations
Data is normally distributed. Table 3.2. shows the correlations between the scores of the BD patients on the different scales of the NEO-FFI and the SIPP-SF, and the scores on the QIDS and YMRS. Higher scores on neuroticism were associated with less manic symptoms (p < .05). Scores on relational capacities showed a significant positive correlation with YMRS scores (p < .05), indicating that more adaptive relational capacities are associated with more manic symptoms. On the other hand, scores on relational capacities showed a significant negative correlation with QIDS scores (p < .05). Indicating less adaptive relational capacities are associated with more depressive symptoms No other significant correlations were found.
Table 3.2. Correlations of scores of BD patients on NEO-FFI, SIPP-SF, YMRS and QIDS. Pearson correlations
NEO-FFI subscales YMRS QIDS
Neuroticism -.68* .43 Extraversion .44 -.59 Openness to experience .18 -.53 Agreeableness -.37 -.22 Conscientiousness .12 -.29 SIPP-SF subscales Self-control .28 -.53 Identity integration .52 -.38 Responsibility -.003 .17 Relational capacities .62* -.61* Social concordance .24 -.01
Note. ** Correlation is significant at p ≤ .01 (2-tailed). * Correlation is significant at p ≤ .05 (2-tailed).
3.3. Comparison of personality traits between BD and BPD
Results of BPD patients (Morey & Zanarini, 2000) and BD patients on the NEO-FFI subscales are presented in Table 3.3. BD patients scored on the NEO-FFI scales mainly between M = 27.6 (SD = 3.83) and M = 30.8 (SD = 8.20), indicating average scores on these domains (Costa & McCrae, 1992). However, scores of BD patients on the neuroticism scale were higher (M = 38.0, SD = 6.80).
Table 3.3. Personality traits (NEO-FFI) in BD, BPD and healthy population (HP)
BD HPa BPDb BD vs. HP BD vs. BPD
Mean (SD) Mean (SD) Mean (SD) t p t p
N 38.0 (6.80) 19.1 (7.7) 35.1 (7.0) 9.22 .001** 1.43 .183 E 30.5 (6.15) 27.7 (5.9) 22.6 (6.9) 1.49 .268 4.24 .002** O 30.8 (8.20) 27.0 (5.8) 29.8 (6.6) 1.55 .153 .41 .689 A 27.6 (3.83) 32.8 (5.0) 30.4 (6.7) -4.74 .041* -2.35 .041* C 28.7 (4.63) 34.6 (5.9) 28.6 (28.56) -4.25 .002** .08 .944
Note. a Costa & McCrea, 1992, b Morey & Zanarini, 2000, ** p ≤ .01 (2-tailed) * p ≤ .05 (2-tailed) Neuroticism (N), Extraversion (E), Openness to experience (O), Agreeableness (A), Conscientiousness (C)
Based on the computed subscales, significantly high levels of neuroticism (t (10) = 9.222, p ≤ .001, M = 38.0; SD = 6.80), and significantly low levels of conscientiousness (t (10) = -4,254, p ≤ .01, M = 28.7; SD = 4.63) and agreeableness (t (10) = -4,74, p ≤ .001, M = 27.6; SD = 3.83) were found in BD patients compared to healthy controls. Compared to BPD patients, BD patients report comparable scores on neuroticism, openness and conscientiousness. However, t-tests showed that BD patients show significantly lower scores on agreeableness (t (10) = -2,351, p ≤ .05, M = 27.6; SD = 3.83), and significantly higher scores on extraversion (t (10) = -4.254, p ≤ .01, M = 30.5; SD = 6.15), compared to BPD patients.
3.4. Comparison of personality states between BD and BPD
Results on the SIPP-SF scales from the BD patients and matched BPD patients are shown in Table 3.4.
Table 3.4. Personality states (SIPP-SF) in BD and BPD patients.
BD BPD BD vs. BPD Mean (SD) Mean (SD) F p Self-control 32.2 (5.95) 34.8 (7.62) .80 .381 Identity integration 25.5 (5.22) 34.2 (4.86) 17.18 .001** Responsibility 31.2 (3.60) 31.0 (6.12) .01 .932 Relational capacities 32.1 (4.89) 36.2 (4.95) 3.94 .060 Social concordance 34.6 (3.38) 28.4 (6.03) 8.07 .010* Note. N = 22. ** p ≤ .001, * p ≤ .01
Figure 3.1. and Table 3.4. show the results of an ANOVA comparing group differences on the SIPP-SF scales between BD and BPD patients. Variables were checked on normality, homogeneity of variances, and outliers. All the assumptions were met. Analysis showed that the BD and BPD patients did not differ on self-control, responsibility, and relational capacities scales. However, a significant difference was found on the identity integration scale (F (1, 21) = 17.182, p < .001). Mean scores indicated that BD patients (M = 25.5, SD = 5.22) experience significantly more problems regarding identity integration than BPD patients (M = 34.2, SD = 4.86). Statistically significant group differences were also found regarding social concordance (F = 222.016, p < .01). BD patients (M = 34.6, SD = 3.38) experience less problems considering social concordance than BPD patients (M = 28.4,
SD = 6.03).
Figure 3.1. ANOVA of SIPP-SF scales between BD and BPD patients
Discussion
The present study can be viewed within a broader context of current research regarding the relationship between BD and BPD, especially considering the diagnostic confusion between both disorders. Several researchers asserted that BD patients are wrongly diagnosed with BPD (Ghaemi et al., 2014). Overlapping symptoms are considered a possible cause for the misdiagnosis of BD as BPD (Zimmerman et al., 2014). However, little research has been done regarding personality factors as a possible underlying cause for the diagnostic confusion. Therefore, the present study aimed to enrich the available research on differences and similarities between BD and BPD, by comparing personality profiles of the two disorders. In general, it was found that personality profiles of BD and BPD patients show overlap on most of the trait and state scales. However, significant differences have been found as well.
4.1. Personality traits in BD and BPD
Consistent with the work of Barnett et al. (2011) and Kotov et al. (2010), high neuroticism scores, and low conscientiousness and agreeableness scores were associated with BD. These results were similar to the personality profile found in BPD patients (Morey & Zanarini, 2000). However, BD patients showed significantly higher levels of extraversion in contrast to BPD patients. These findings contrast with those of Barnett et al. (2011) who found low extraversion scores to be characteristic of bipolar patients, but are in line with those of Akiskal (2004), and Quilty, Sellbom, Tackett and Bagby (2009) who did find elevated extraversion scores in BD patients as well. A possible explanation for these conflicting findings could be the influence of mood state on extraversion. Although Barnett et al. (2011) found their results during euthymic periods as well, residual symptoms may account for their findings. No associations were found between depressed or manic symptom severity and the extraversion subscale of the NEO-FFI in this study. A possible reason for this could be, considering that the NEO-FFI scales are more trait like, that BD patients show higher levels of extraversion overall, even during depressive episodes. A study by Lam, Wright and Sham (2005) characterized BD patients to value attributes of extraversion, such as being outgoing, and perceive themselves often to possess these attributes, which could explain a higher level of extraversion. Smillie, Cooper, Wilt and Revelle (2012) explained elevated extraversion in bipolar patients as a coping mechanism. They associated extraversion with higher positive affect, and found individuals who behaved in a more extraverted way to experience an increased positive affect. Enhanced positive emotions can serve to downregulate negative
emotions (Carl, Soskin, Kerns & Barlow, 2013). Higher levels of extraversion could indicate a tendency to avoid a negative affect, as a compensatory mechanism of BD patients in an attempt to avoid depressive feelings (Pavlickova et al., 2013).
BD patients appeared to score lower on agreeableness compared to BPD patients. This is a remarkable insight considering that less agreeableness, hostility even, is more often seen in BPD patients (Henry et al., 2001). A possible explanation for the lower agreeableness scores in BD could be the goal-directed behaviour to positive-emotion related situations as seen in BD (Carl et al., 2013). Different categories of positive emotions can be identified (e.g. self-focused, prosocial, achievement-related). It is possible that the behaviour of BD patients directed toward positive emotions, is marked by decreased participation in other positive situations, for instance prosocial interactions (Carl et al., 2013). In addition, Mansell and Lam (2006) found that people with BD use less feedback from others, leading to less agreeableness.
4.2. Personality states in BD and BPD
As predicted, scores of BD and BPD patients on personality states in different domains showed overlap as well. Both bipolar and BPD patients showed impaired adaptive functioning on all dimensions. Scores were worst for both patient groups on self-control, relational functioning, and responsibility scales. These results indicate that BD patients have, similar to BPD patients, an impaired capacity to control emotions and impulses, problems with intimate and enduring relationships, and are less able to set realistic goals and to achieve these goals in line with the expectations in others. Impaired goal-directed behaviour in BD patients has been reported before. Johnson (2005) found individuals with BD to endorse more elevated life ambitions and heightened appraisal of goals compared to healthy individuals. In addition, previous research showed that BD patients do not decrease their effort toward an ambition or goal after exceeding their goal expectations in contrast to healthy controls (Fulford, Johnson, Llabre & Carver, 2010).
Surprisingly, BD patients were found to experience more problems with identity integration compared to BPD patients. This is rather remarkable since identity disturbances are an important feature of BPD according to the DSM (American Psychiatric Association, 2000) and literature describing individuals with BPD as having a markedly unstable self-image (Wilkinson-Ryan & Westen, 2000; Zeigler-Hill & Abraham, 2006). A possible
explanation for the fact that the BD patients in the current sample report more identity problems than BPD patients, might be an instable mood state in BD patients at the time of assessment. Pavlickova et al. (2013) and Knowles et al. (2007) characterized individuals with BD as having marked short-term fluctuations in esteem, dysfunctional attitudes and self-discrepancies, indicative of a disturbed underlying self-schema, dependent upon the phase of illness. For instance, manic symptoms were associated with avoidance of attributing negative events to themselves and an abnormally low discrepancy between perceptions of the actual self and ideals. However, in this study no association was found between mood state and scores on the identity integration subscales.
Another possible explanation for these findings could be the onset of BD which occurs during critical developmental phases and tasks such as the developmental trajectory of one’s identity (Morris, Miklowitz & Waxmonsky, 2007). Frequent fluctuations in mood at a young age interrupts identity consolidation and could have wide-ranging effects later in life (Morris et al., 2007). Furthermore, it is clinically observed that BD patients identify themselves with a (hypo)manic state of constant high arousal, positive mood and being behaviorally active (Lam et al., 2005). They often aspire to achieve this sense of self. This could indicate that these unrealistic beliefs of bipolar patients regarding their identity could contribute to a dysfunctional self-image, and may cause more identity integration difficulties.
Although BD patients experienced more identity problems, they experienced less social concordance problems than BPD patients. These results implicate that BD patients are better able to regulate their aggressive impulses and frustration, are more cooperative and respectful, and are better able to work together with others, compared to BPD patients. These findings are in line with findings by Bayes et al. (2014) who described bipolar patients, when not manic, as being more unlikely to show pathological relationships compared to BPD patients, and as tending to maintain stable relationships.
4.3. Mood state
Although results from earlier studies (Barnett et al., 2011; Hawken et al., 2016; Scott & Pope, 2003) highlight the importance of taking the phase of illness into account when examining personality states and traits, mild manic symptoms were reported by only some bipolar patients or researchers and results indicated mild to severe depression in all of the BD patients. Mood state influenced in this study scores of BD on different trait and state scales only to some extent. Elevated neuroticism was associated with less manic symptoms. This
matches results of Quilty et al. (2009), who even associated neuroticism with symptoms of depression. In this study symptoms of depression were associated with less relational capacities. This is supported by Hammen and Watkins (2008) who described patients with symptoms of depression as experiencing difficulties in their relationships with others due to lesser social skills. Patients with depression were less verbally fluent, had more monotonous speech, and made less eye contact. They failed to engage others and to respond with interest, so that interacting with them was unrewarding. Interestingly, manic symptoms were associated with less problems regarding relational capacities. These findings are contrasted by other studies and existing literature, which show impairments of BD patients in interpersonal relations and disabilities in psychosocial functioning specifically during severe mania or depression (Mehta, Mittal & Swami, 2014). However, it is found that bipolar patients are more sociable during mild to moderate (hypo)manic states (Lam et al., 2005), which could explain the association with better relational functioning and manic symptoms.
4.4. Implications
The broad theoretical implication of this study includes the associations that have been made in personality profiles between BD and BPD patients. Although results are preliminary, this study adds to the growing literature regarding BD and BPD, and contributes to the understanding of fundamental similarities and differences between the two disorders regarding personality. Conclusions of Barnett et al. (2011) and Morey and Zanarini (2000) are extended. Not only is affective instability a shared characteristic of BD and BPD (Benazzi, 2006; Zeigler-Hill & Abraham, 2006), similarities are also found between BD and BPD on other personality domains such as neuroticism, conscientiousness, and self-control.
The practical benefit of these findings concerns the treatment process. While symptoms change within individuals over time, personality traits remain stable over the life course (Barnett et al., 2011). FFM traits could be used to predict patient functioning in the future (Hopwood & Zanarini, 2010). It is important to note however that current mood episodes of BD patients should be taken into account. The findings of this current study regarding the identity problems of BD patients could contribute to more custom-made therapy. By analysing personality factors of patients, a more accurate treatment plan could be made. Therapy of BD focuses currently mainly on preventing relapses, improving social functioning, and improvement of depressive symptoms (Antoniadis et al., 2012). Cognitive-behavioural therapy and psychoeducation are considered effective (Jabben & Arts, 2011).
However, more effective progress could be made by focusing on self-esteem as well as on more adaptive identity integration. Combined therapy could also be considered for BD patients, for instance with elements of dialectic-behaviour therapy effective for BPD (Antoniadis et al., 2012), focused on affect regulation and improvement of self-worth.
In order to establish whether symptoms are best attributed to BD or if they are more representative of BPD, a therapist must decide if a patient’s instability is more a manifestation of a mood or a personality disorder (Hatchett, 2010). Recognizing the relationship between the two disorders is the first step to subsequently identifying their optimal management and treatment (Antoniadis et al., 2012). It is important for clinicians to understand the fundamental differences between the two disorders (Aboaja, Duggan & Park, 2011). However, differentiating between the two disorders based only on personality assessment will be difficult considering the significant commonalities of personality factors and problems. Other clinical differences may be more sensitive for the diagnostic distinction between BD and BPD. According to Bayes et al. (2014), the most useful discriminating factors are phenomenological differences in terms of mood and age of onset. For instance, the majority of BD (hypo)manic episodes are characterized by euphoric anxiety-free states, in contrast to the hostility and anxiety periods of BPD patients. In addition, BD is most likely to have a sharp onset period, whereas BPD would appear to evolve from childhood. Coulston, Tanious, Mulder, Porter and Malhi (2012) underline other parameters as being of some discriminating use. For instance, the difference regarding impulsivity. They found BD to be uniquely associated with attentional impulsiveness, compared to BPD which was associated with a greater level of motor or non-planning impulsiveness (Coulston et al., 2012). However, these results require careful consideration of the context rather than prevalence only (Bayes et al., 2014).
This study provides evidence for the advocation of a personality taxonomy as a potential framework for the description of the overlap and variation in BD and BPD (Hu et al., 2014). A dimensional approach can explain heterogeneity in symptomatology and the lack of clear boundaries between BD and BPD. The DSM-5 already represents a shift in the conceptualization of BD from one of discrete categories, to a more dimensional spectrum of symptoms. A dimensional representation has been established for personality disorders as well (Distel et al., 2009).
4.5. Limitations
Some limitations are worth noting. Participation was voluntary and depended on the motivation of the patients. It is possible that patients with less severe symptomatology were interested in participation, which could imply that patients with a more severe presentation of the illness could not be included. Moreover, the sample of included patients was a lot smaller than anticipated. Possible reasons for this were the strict inclusion criteria, the selection of patients that were only very recently diagnosed (maximum of 4 months) and had never received treatment for BD in the past. As a consequence of the small sample size, the statistical power of the study is low. Therefore, the results cannot be generalized to the larger bipolar population and should be interpreted with caution. Replication in larger samples is warranted.
Although validated measurements were used, all the instruments were self-report questionnaires. This may have caused problems for patients with less introspective ability, and less accurate responses. In addition, the NEO-FFI and SIPP-SF may not also capture all personality variation (Morey & Zanarini, 2000). Patients may also have varied regarding their understanding of the questions. This could have been especially problematic considering the abstract concept of personality. Egan, Deary and Austin (2000) state that neuroticism, agreeableness, and conscientiousness scales, are more reliable than openness to experience and extraversion. This would imply that the results found regarding extraversion especially should be interpreted with caution. It should be explored whether future research will be able to obviate these limitations. However, an informant-based measure would have been difficult to implement, and perhaps have been useless (Barnett et al., 2011). It is questionable whether self-reports of personality would differ widely from those of informants. Follow-up research is necessary to determine the reliability of the trait and state scales in BD patients.
While scores of the NEO-FFI were compared between BD and BPD patients, no actual data from BPD patients was obtained regarding the NEO-FFI. Retrieved data was compared to samples from other countries who used different research procedures. It would be beneficial to collect data from BPD patients as well, to compare more reliably with BD patients.
Personality assessments were conducted from one week before to one week after the baseline measurement. This delay in assessments might have introduced error in the association between personality factors and mood state among patients with rapid changes in mood state. More importantly, none of the patients reported severe manic symptoms. This might have complicated analysis of the influence of mood state on personality states and
traits. Comorbidity of BD patients may have been a limitation as well. It is possible that a proportion of the differences in scores between the BD group and the BPD group reflect differences caused by comorbidity in the BD group. However, comorbidity of BD patients was not known.
4.6. Future research
The similarities and differences found by this study are promising and should be explored further within the longitudinal prospective (BINCO) study, to require a better understanding of the diagnostic boundaries between BD and BPD (Fornaro et al., 2016). Further, larger quantitative assessments of the overlapping and differential personality traits are needed for a more refined establishment of personality profiles of the two patient groups. Since bipolar symptoms and personality states are inherently unstable over time, this presents a special challenge for understanding the underlying mechanisms. Therefore, frequent follow-up measurements are necessary to detect all associations. Future research may consult other personality models as well to capture all elements of personality. Some elevations in traits or states may be expected from a social and developmental perspective (Henriques-Calado et al., 2014).
Conclusion
The aim of this study was to establish differences and similarities in personality traits and states between BD patients and BPD patients. In general, personality profiles of both patient groups tend to overlap. However, differences were found regarding elevated extraversion, more identity problems, and less social concordance difficulties of BD patients compared to BPD patients. Overall, the current findings contribute to the existing knowledge of the association between BD and BPD. The results can be used to integrate personality traits and states into the clinical assessment of BD and BPD, and perhaps to offer a better insight into the factors allowing an accurate distinction between the disorders to prevent misdiagnosing. But, most importantly, these results can contribute towards the achievement of more accurate therapeutic interventions. Future research is recommended to further identify personality profiles and generalize results to a larger population. Elements of traits and states may be important for clinical predictions of patient functioning, and to differentiate between BD and BPD.
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