The Effect of Childhood Trauma on Adult Social
Withdrawal in Patients with Psychotic Disorders and
the Mediating Role of Self and Other Beliefs
Masterthesis
Department of Psychology
04-09-2017
Name: E.L. Roos
Student number: 10359192 Number of words: 5882 Supervisors
Specialization: L.L.N.J. Boyette, PhD External supervisor: N.F. Schirmbeck, PhD
2 Index Abstract 3 1. Introduction 4 2. Method 9 2.1 Participants 9 2.2 Procedure 10 2.3 Materials 10 2.4 Statistical analyses 12 3. Results 13 3.1 Sample characteristics 13
3.2 Type of childhood trauma and social withdrawal 15 3.3 Type of childhood trauma and self- and other –beliefs 16 3.4.1 Mediation model for child physical abuse in patients
with psychotic disorders 17
3.4.2 Mediation model for child physical abuse in patients
with psychotic disorders 18
4. Discussion 19
3 Abstract
Childhood trauma (CT) has been associated with social withdrawal in patients with psychotic disorders, although mechanisms are yet unclear. The current study intends to elucidate this relation in a subsample of patients with psychotic disorders who participated in a nationwide cohort study (the GROUP study). First it was investigated which types of CT are associated with social withdrawal. Then it was examined which types of CT are associated with negative and positive self- and other-beliefs. Thereafter, a mediation model was tested in order to explore whether self- and other-beliefs mediate the relation between types of CT and social withdrawal. Finally, the mediation was repeated in healthy controls to test replicability in the general population. The current sample consisted of 240 patients with psychotic disorders and 116 healthy controls. All participants completed the Child Trauma Questionnaire-Short Form, Brief Core Schema Scale and the Social Functioning Scale. Results show that physical abuse and physical neglect were associated with social withdrawal. Physical abuse was positively associated with negative self- and beliefs and negatively associated with positive other-beliefs. Physical neglect was negatively associated with positive other-other-beliefs. The mediation of positive other-beliefs on the relation between physical abuse and social withdrawal was significant. After including positive and depressive symptoms, it lost significance. Similar results were found for healthy controls. Current findings suggest that positive other-beliefs mediate the relation between physical abuse and social withdrawal. However, variance was explained by confounders like depressive symptoms. Further underlying mechanisms are still unclear.
4 1. Introduction
Psychosis is a mental state where patients lose their connection with reality and process information in an anomalous way(Bentall & Kaney, 1989). Schizophrenia is a psychotic disorder where people suffer for at least one month from two or more positive symptoms which include delusions (false beliefs), hallucinations (false sensory perceptions), disorganized speech and grossly disorganized or abnormal motor behavior, and negative symptoms. Negative symptoms include diminished emotional and physical expression, a lack of initiation of activities, a lack of interest in social interactions and a diminished experience of pleasure. To be diagnosed with schizophrenia, patients need to experience problems for a minimum of six months(Association, 2000).
Multiple studies indicate that patients with psychotic disorders have experienced more childhood trauma (CT) compared to the general population(Bebbington et al., 2004; Rubino, Nanni, Pozzi, & Siracusano, 2009; Spence et al., 2006). After experiencing CT, there is a roughly threefold increase in risk of developing a psychotic disorder(Varese et al., 2012). In particular, evidence has been found for a relationship between CT and positive symptoms(R. P. Bentall, Wickham, Shevlin, & Varese, 2012; Janssen et al., 2004; Read, Agar, Argyle, & Aderhold, 2003). Kilcommons & Morrison (2005) found sexual abuse to be associated with hallucinations specifically. Read, van Oss, Morrison and Ross (2005) found emotional abuse to be strongly correlated to auditory hallucinations and Abajobir et al. (2017) found particularly emotional abuse and neglect to increase the probability to develop hallucinations and delusions. However, more recent studies reported an association between CT and negative symptoms as well(Alemany et al., 2013; van Dam et al., 2015). Isvoranu et al. (2017) indicated through network analysis that neither positive nor negative symptoms are directly associated with CT, but that they are mediated by general psychopathology.
5 Depression is a factor which may contribute to this network as part of more general psychopathology.
There are different kinds of CT which can be divided into the following categories: physical abuse, sexual abuse, emotional abuse, physical neglect and emotional neglect(Bernstein et al., 2003). Many contradicting results have been found when it comes to the influences of each individual type of CT. Trauelsen et al. (2015) found that the shared effect of CT was bigger than the effects of each individual type of CT to the risk of psychosis. However, other studies did report that individual types of CT had different effects on the development of psychosis. Various studies found physical abuse to be the only predictor for psychosis in contrast to sexual abuse, neglect and other forms of child adversities after controlling for demographic confounders(Fisher et al., 2010) and depression(Shevlin, Dorahy, & Adamson, 2007). Other studies found that only sexual abuse was associated to the transition to psychosis in contrast to neglect, physical, emotional and other trauma’s in a population with a high risk of psychosis(Bechdolf et al., 2010; Thompson et al., 2014). Another study suggested that only emotional abuse was associated with transitioning to psychosis(Kraan et al., 2017). Daalman et al. (2012) indicated that neglect was less associated with the risk of psychosis compared to physical, sexual and emotional abuse. Neglect was more associated with general psychopathology(Heins et al., 2011).
Garety, Kuipers, Fowler, Freeman and Bebbington (2001) devised a cognitive theory of how CT can increase the vulnerability of psychosis. They speculated that by experiencing CT, negative beliefs about the self and others can be developed. These negative schemas may create cognitive vulnerability and increase sensory sensitivity for hostile cues, which can cause paranoid ideas. Core schemata are cognitive generalizations of positive and negative evaluations about the self and others, formed by previous experiences, which correlate high to one another(Fowler et al., 2006). Negative self-beliefs were indicated to mediate the relation
6 between CT and the risk to develop psychosis(Appiah-Kusi et al., 2017), and others found both negative self-beliefs and negative other-beliefs to be mediators in vulnerability of psychosis(Gracie et al., 2007; Jaya, Ascone, & Lincoln, 2017; Taylor et al., 2014). The same cognitive model could be applicable in the increase of social withdrawal. Social isolation can lead to the acceptance of psychotic experiences, because accessibility of alternative explanations that other people contribute decreases(White, Bebbington, Pearson, Johnson, & Ellis, 2000). Healthy controls were found to have less negative beliefs about the self and others compared to people with an high risk of psychosis(Appiah-Kusi et al., 2017). Yet, there were found no lower positive other-beliefs in patients compared to healthy controls(Fowler et al., 2006). A possible explanation why no lower positive self-beliefs were found in the patient population may be due to grandiosity symptoms(Taylor et al., 2014). Others found that negative beliefs are a frequent consequence of CT in patients with psychotic disorders(Birchwood, 2003; Garety, Kuipers, Fowler, Freeman, & Bebbington, 2001) and seem to play a role in the relation between CT and symptoms of psychosis(Kesting & Lincoln, 2013). Negative self- and other-beliefs have also been associated with poorer social functioning(James et al., 2016) and social withdrawal specifically in patients with psychotic disorders(Barrowclough et al., 2003). In a study with people with high risk of psychosis, neglect was indicated to have an impact on negative beliefs compared to physical abuse, sexual abuse and emotional abuse(Appiah-Kusi et al., 2017). Physical abuse was found to be only associated with negative other-beliefs, although positive beliefs were not included in that study(Hardy et al., 2016). Hardy et al. (2016) also found the relation between emotional abuse and psychosis to be mediated by negative beliefs, but the relation between sexual abuse and psychosis not to be mediated by negative beliefs. However, the majority of studies used a total amount of CT instead of types of CT separately. Moreover, apart from group comparisons between patients with psychotic disorders and healthy controls, the effect of CT
7 on negative and positive self- and other-beliefs has not been investigated in a patient population so far. Further research is required to comprehend the association between types of CT and negative and positive self- and other-beliefs in patients with psychotic disorders.
Besides negative beliefs was social withdrawal suggested to be a risk factor for the onset of psychosis(Velthorst et al., 2009) and additionally part of a vicious circle where it increases negative symptoms and deteriorates overall social functioning and quality of life(Siegrist, Millier, Amri, Aballea, & Toumi, 2015). When social withdrawal improves, this vicious circle may be broken and ameliorate the prognosis of psychosis. Patients with psychotic disorders and CT report more social withdrawal in comparison with patients without CT(Boyda & McFeeters, 2015; Boyette et al., 2014; Spence et al., 2006; Stain et al., 2014). So far little is known about the association between social withdrawal and specific types of CT. Negative self- and other-beliefs can have disastrous implications for someone’s social life. Feeling worthless and finding others threatening, may cause people to withdrawal themselves from social situations(Barrowclough et al., 2003).
To the best of our knowledge, it has not been investigated if core schemata may have a mediating effect on the association between types of CT and social withdrawal in patients with psychotic disorders. To examine these aims, a couple of factors need to be controlled for. The first is depression. CT has been linked to symptoms of depression in a psychotic population(Hafner, Loffler, Maurer, Hambrecht, & an der Heiden, 1999; van Dam et al., 2015). After a traumatic childhood, a depressive state of mind can cause patients with psychotic disorders to isolate themselves and show more social dysfunction(Hirschfeld et al., 2000). The second is positive symptoms. Positive symptoms, like paranoid delusions, can cause patients to isolate themselves(Hansen, Torgalsboen, Melle, & Bell, 2009).
The following research questions have been formed to elucidate the relation between CT and social withdrawal in patients with psychotic disorders: (1) Are different types of CT
8 associated with social withdrawal in patients with psychotic disorders? (2) Are types of CT associated with self- and other-beliefs in patients with psychotic disorders? (3) Do self- and other-beliefs mediate the relation between types of CT and social withdrawal in patients with psychotic disorders? As well as when controlling for positive and depressive symptoms? (4) If so, can the mediation model found under 3 be replicated in healthy controls?
The hypothesis for the first research question was that the higher the frequency of reported type of CT, the more social withdrawal patients with psychotic disorders show ( which would result in a negative association, because lower scores on the Social Functioning Scale mean more social withdrawal). Based on previous literature, physical abuse, sexual abuse and emotional abuse were expected to correlate negatively with social withdrawal. Physical neglect and emotional neglect were expected not to be related to social withdrawal in patients with psychotic disorders.
Based on previous literature, the hypothesis for the second research question was that physical and emotional neglect associate positively with negative self-beliefs, that emotional abuse relates positively with negative self- and other-beliefs and that physical abuse correlates positively with negative-other beliefs. Sexual abuse is expected not to be associated with any self- and other-beliefs. Because negative and positive beliefs are correlated, it is also expected that the types of CT are negatively associated with the corresponding positive self- and other-beliefs. Which results in that physical and emotional abuse are expected to be correlated with positive self-beliefs, emotional abuse is expected to correlate with positive self- and other-beliefs and that physical abuse correlates with positive other-other-beliefs.
The third research question was partly explorative and depended on the significant correlations (p <.01) found in the results of research questions 1 and 2. The hypothesis was that there are positive indirect effects of especially negative self- and other-beliefs, and negative indirect effects of positive self- and other-beliefs on the relation between sexual
9 abuse, physical abuse and emotional abuse and social withdrawal. Figure 1 shows the hypothesized mediation model.
Because the essence of the fourth research question was explorative, there were no a priori predictions about the proposed mediation. The purpose of replicating the mediation model in healthy controls was to explore whether the mediation is not only explained by psychotic symptom related factors but also applicable in the general population.
+ +
- - + +
- -
Figure 1. The hypothesized mediation between types of childhood trauma and social withdrawal by self- and
other-beliefs. The underlined types of childhood trauma are expected to be significant.
2. Method 2.1 Participants
The current study used data from a subsample of the longitudinal GROUP (Genetic and Risk Outcome of Psychosis) cohort study(Korver, Quee, Boos, Simons, & de Haan, 2012). The GROUP study was designed and conducted by four academic centers and regional psychosis departments in the Netherlands in the regions Amsterdam, Groningen, Utrecht and Maastricht. To be included, patients had to meet the following criteria: 1) a diagnosis of non-affective psychotic disorder according to the DSM-IV(Association, 2000); 2) age ranged from 16 to 50; 3) fluent in Dutch.
Controls were randomly contacted through email and through advertisements. The inclusion criteria for the controls were: 1) age ranged from 16 to 50; 2) no lifetime psychotic
Positive Self-Beliefs
Positive Other-Beliefs Negative Other-Beliefs Sexual, Physical and
Emotional abuse and Physical and Emotional Neglect
Social Withdrawal Negative Self-Beliefs
10 disorder diagnosis; 3) no first degree family member with a lifetime psychotic disorder diagnosis; 4) fluent in Dutch.
Power analysis with G-Power version 3.1.9.2, using α = .05 with a small to medium effect size ρ = .20, showed a necessary sample size of 191 participants to achieve the a power level of 0.8.
2.2 Procedure
The GROUP study was designed to investigate vulnerability and resilience factors for onset and/or relapse of people with non-affective psychotic disorders, their unaffected family members (siblings and parents) and healthy controls. In total, 1045 patients, 1123 siblings, 923 parents and 641 healthy controls were included. For the current study, only patients and healthy controls were included. Participants of the GROUP study were followed for six years and had three measurements; T0 (baseline), T2 (first follow-up after three years) and T3 (second follow-up after six years)(Korver et al., 2012). The Brief Core Schema Scales, which were needed for the current study, were only administered at T3. Thus, information for the current study was selected at the third measurement moment. The following variables were selected: experience of CT; self- and other-beliefs; social withdrawal; positive symptoms; depressive symptoms and sociodemographic characteristics.
2.3 Materials
Frequency of traumatic experiences before the age of 16 was assessed with the Dutch version of the Childhood Trauma Questionnaire-Short Form (CTQ-SF)(Bernstein et al., 2003). The CTQ-SF is a self-report questionnaire with 25 items which are scored on a five point Likert scale that range from ‘never true’ to ‘very often true’. An example question is: “During my childhood (before the age of 16) I was hurt because I did not do something sexual”. CT is divided into five continuous scales; physical, sexual and emotional abuse, and
11 physical and emotional neglect. The Dutch version of the CTQ-SF has a good internal consistency and validity in the general population and a clinical sample which consists of anxiety, mood, psychotic, substance, eating and somatoform disorders(Thombs, Bernstein, Lobbestael, & Arntz, 2009; Thombs, Lewis, Bernstein, Medrano, & Hatch, 2007).
Social withdrawal over the last three months was assessed with a subscale of the Social Functioning Scale (SFS)(Birchwood, Smith, Cochrane, Wetton, & Copestake, 1990). This a 24-item self-report questionnaire with questions like “How many friends do you have at the moment?”. The SFS is divided into seven subscales; withdrawal, interpersonal behavior, prosocial activities, recreation, independence-performance, independence-competence and employment. The social withdrawal scale includes five items ranging from 0 to 3 per item, with a minimum score of 0 and a maximum score of 15 of the raw scores. In the current study, scaled scores were used. The scaled scores range from 57.5 to 133.0 with a mean of 100 and standard deviation of 15. Low scores on the withdrawal scale mean more social withdrawal. There has been found strong support for the reliability and validity of the SFS in the general population and in patients with psychotic disorders(Birchwood et al., 1990).
Self- and other-beliefs were assessed with the Brief Core Schema Scale (BCSS). The BCSS is a 24-item self-report questionnaire with positive and negative beliefs about the self and others. Statements like “I am worthless” (negative self-belief), “I am successful” (positive self-belief), “others are hostile” (negative other-belief) and “others are supportive” (positive other-belief) can be answered with ‘no’ or ‘yes’ with a four point Likert scale ranging from ‘believe it slightly’ to ‘believe it totally’. The psychometric properties and construct validity are good in both patients with psychotic disorders and the general population(Fowler et al., 2006).
Depressive symptoms were measured with the Community Assessment of Psychic Experiences(CAPE) This is a 42-item self-report questionnaire with positive and negative
12 psychotic experiences dimensions, and a depressive dimension with eight symptom items. In the current study, only the depressive and positive dimensions were used. For every feeling, thought or mental experience the frequency and associated distress are measured. Frequency can be rated on a four point Likert scale ranging from ‘never’ to ‘nearly always’. Distress can also be rated on a four point Likert scale ranging from ‘not stressed’ to ‘very stressed’. An example question is “How often did you feel sad in the last three years?”. Only measures of frequency were used in the current study. The CAPE has good reliability and validity(Konings, Bak, Hanssen, van Os, & Krabbendam, 2006).
Positive symptoms of the patients with psychotic disorders were measured with the Positive and Negative Symptom Scale (PANSS)(Kay, Flszbein, & Opfer, 1987). The PANSS is a 30-item semi-structured interview with questions like “Have you had any weird or unusual experiences?”. Symptoms can be rated on a seven point Likert scale ranging from ‘absent’ to ‘extreme’. The items are divided in three subscales: positive symptoms, negative symptoms and general psychopathology scale. The validity and reliability are acceptable to good(Kay, Opler, & Lindenmayer, 1988). Positive symptoms of healthy controls were measured with the positive dimension of the CAPE because the PANSS was not conducted with the healthy control group. The PANSS was designed for clinical symptoms whereas the CAPE was designed for the general population.
2.4 Statistical Analyses
For all analysis IBM SPSS Statistics version 24 was used. To determine the difference in sociodemographic characteristics in the patient and healthy control group, chi-square tests were used for categorical variables, and independent t-tests were used for continuous variables.
To investigate which type of CT was associated with social withdrawal, non-parametric Spearman’s correlations were used, as previous GROUP studies that investigated CT found
13 that CT was distributed non-paranormal(Boyette et al., 2014; Frissen, Lieverse, Drukker, van Winkel, & Delespaul, 2015). The same procedure was used to test which type of CT was associated with negative self- and other-beliefs and positive self- and other-beliefs in patients with psychotic disorders. Correction for alpha inflation was accomplished by a calculation of alpha (α = .05) divided by the number of correlations per research question.
To test the mediation of self- and other-beliefs on the relation between type of CT and social withdrawal in patients with psychotic disorders, PROCESS(Hayes, 2012) was used. PROCESS is a modeling tool for SPSS that integrates statistical tools for mediation analysis. An individual mediation model was used for every significant association (p <.01) found in research question 1 and 2. After all mediation analyses were performed, the mediation analyses were repeated with positive symptoms, measured with the PANSS, and depressive symptoms, measured with the CAPE, included to control for confounders or covariates in the patient group. The same procedure will be managed with the healthy control group. Except in the healthy control group, subclinical instead of clinical positive symptoms were measured, using the CAPE.
3. Results 3.1 Sample characteristics
Primarily, 337 participants were included in the patient group and 124 participants were included in the healthy control group. Due to missing data, a sample of 240 patients and 116 healthy controls remained that completed the CTQ-SF, SFS and BCSS. The consideration to exclusively select participants who completed all three questionnaires was to create similar samples for every research question. Sociodemographic and clinical characteristics of the patients and healthy controls are shown in Table 1. Results of the Kolmogorov-Smirnov test for normality confirmed that all types of CT were significantly different from a normal distribution (p <.001).
14 Table 1
Sociodemographic and Clinical Characteristics in Patients and Healthy Controls
Patients Healthy Controls
Age (M, SD) 33.71 (7.43) 39.58 (10.32) *** Gender (% male) 75 62.9 ** IQa (M, SD) 102.89 (18.32) 113.54 (18.46) *** Ethnicity (% Caucasian) 79.2 89.7 Marital Status (%) Not married 81.3 33.6 *** Married/living together 15.4 58.6 *** Divorced 3.3 6.9 Widowhood 0.9
Age of onset first psychosis (M, SD) 23.60 (6.92) DSM diagnosis (%)
Schizophrenia 53 (N = 127)
Schizophreniform disorder 5.4 (N = 13) Schizoaffective disorder 8.8 (N = 21)
Delusional disorder 1.3 (N = 3)
Psychotic disorder NOS 7.1 (N = 17)
Other psychotic disorders 24.8 (N = 59)
Note: a IQ was assessed with 4 subtests of the Wechsler Adult Intelligence Scale-III (WAIS-III). M: mean, SD: standard deviation, N: total number of participants. Significance levels for group-comparisons: **p <.01, ***p <.001
Independent samples t-tests and chi-square tests were performed to evaluate the differences between the patient and healthy control groups. See Table 2 for the SFS, CTQ-SF and BCSS scores of the patients and healthy controls and the comparisons between the two groups. The assumptions for the variables age, emotional and physical abuse, physical neglect, negative self- and other-beliefs and positive self- and other-beliefs were violated because Levene’s test for equality of variances was significant (p <.05). When the assumption of homogeneity of variance is violated, the significance levels can be underestimated, which can cause type I errors. That is why a correction for alpha inflation was performed for research question 1 and 2.
15 Table 2
Social Withdrawal, Childhood Trauma and Self- and Other-Beliefs Scores in Patients and Healthy Controlsa
Scale Group Mean SD Median Minimum to
Maximum SFS Social withdrawal Pt 104.52 12.30 104.50 75.50-133.00 Hc 118.30*** 12.48 124.50 87.50-133.00 CTQ-SF Sexual abuse Pt 1.19 0.55 1.00 1.00-5.00 Hc 1.11 0.39 1.00 1.00-3.40 Physical abuse Pt 1.18 0.40 1.00 1.00-3.60 Hc 1.12 0.32 1.00 1.00-3.40 Emotional abuse Pt 1.77 0.76 1.40 1.00-4.40 Hc 1.53** 0.61 1.40 1.00-3.80 Emotional neglect Pt 2.18 0.82 2.00 1.00-5.00 Hc 1.93** 0.74 1.80 1.00-4.20 Physical neglect Pt 1.39 0.45 1.20 1.00-3.00 Hc 1.22*** 0.35 1.00 1.00-2.60 BCSS Negative self-beliefs Pt 0.50 0.60 0.33 0.00-3.33 Hc 0.16*** 0.30 0.00 0.00-1.67 Positive self-beliefs Pt 1.90 1.00 2.00 0.00-4.00 Hc 2.31*** 0.78 2.33 0.17-3.67 Negative other-beliefs Pt 0.50 0.73 0.17 0.00-4.00 Hc 0.17*** 0.35 0.00 0.00-1.83 Positive other-beliefs Pt 1.72 0.92 1.83 0.00-4.00 Hc 2.16*** 0.68 2.17 0.17-3.67
Note: aPt: patients (N=240), Hc: healthy controls (N=116). Significance levels for group-comparisons: **p <.01, ***p <.001.
3.2 Type of childhood trauma and social withdrawal
To test whether different types of CT are associated with social withdrawal in patients with psychotic disorders, one-tailed non-parametric Spearman’s correlations were conducted. To account for alpha inflation due to multiple testing, alpha was set to p <.01 (0.05 : 5). As expected, there was a significant negative relation found between physical abuse and social withdrawal, rs = -.232, p <.001, and no significant relation between emotional neglect and social withdrawal, rs = -.119, p = .033. Unexpectedly, there was a significant negative association between physical neglect and social withdrawal, rs = -.171, p = .004, and no
16 significant relations between sexual abuse and social withdrawal, rs = -.052, p = .213, and between emotional abuse and social withdrawal, rs = -.145, p = .012.
3.3 Type of childhood trauma and self- and other-beliefs
Non-parametric Spearman’s correlations were also conducted to test the association between types of CT and self- and other-beliefs in patients with psychotic disorders. See Table 3 for the results. To account for alpha inflation due to multiple testing, alpha was set to
p <.003 (0.05 : 20).
Table 3
Correlations Between Type of Childhood Trauma and Self- and Other-Beliefs
Sexual abuse Physical abuse Emotional abuse Emotional neglect Physical neglect Negative self-beliefs rs p .157 .007 .220*** .000 .304*** .000 .117 .036 .106 .050 Positive self-beliefs rs p -.083 .101 -.081 .105 -.101 .059 -.240*** .000 -.099 .063 Negative other-beliefs rs p .017 .395 .207*** .001 .145 .012 .131 .021 .047 .236 Positive other-beliefs rs p -.083 .100 -.180*** .003 -.069 .143 -.241*** .000 -.135 .018 Note: ***Correlation is significant at the 0.003 level (1-tailed)
As hypothesized, negative self-beliefs were positively associated with emotional abuse. Negative other-beliefs were positively associated with physical abuse. There was found a negative association between positive self-beliefs and emotional neglect. And positive other-beliefs were negatively associated with physical abuse and emotional neglect. As expected, sexual abuse was not related to and other-beliefs. Against the hypotheses, negative self-beliefs were not significantly associated with emotional neglect and physical neglect and were expectantly positively associated with physical abuse. Negative other-beliefs were not significantly associated with emotional abuse, emotional neglect and physical neglect. Positive self-beliefs were not significantly related with emotional abuse, physical abuse and
17 physical neglect. At last, positive other-beliefs were not significantly associated with sexual emotional abuse and physical neglect.
3.4.1 Mediation model for child physical abuse in patients with psychotic disorders
Only one mediation model was tested, because physical abuse was the only type of CT that was significantly associated (p <.01) with social withdrawal. Negative self-beliefs, negative other-beliefs and positive other-beliefs were significantly associated (p <.01) with physical abuse, thus they were included as mediators in the model. Figure 2 shows the regression coefficients of all paths between of the model. Significant relations between physical abuse and positive other-beliefs and between positive other-beliefs and social withdrawal indicated an indirect effect of positive other-beliefs on the association between physical abuse and social withdrawal. This result remained after bootstrapping 95% CI [-2.40,-.22]. The total model accounted for roughly 13% of the variance (R2 = .125, F(4,235) = 8.39, p <.001). The model of the direct effect accounted for roughly 4% of the variance (R2 =
.038, F(1,238) = 9.30, p =.003). There were no indirect effects of negative self-beliefs and negative other-beliefs on the relation between physical abuse and social withdrawal.
b = .19 b = -2.51 b = -6.03** (b’ = -3.97*) b = .38** b = -.97 b = -.37*** b = 2.82**
Figure 2. Mediation between child physical abuse and social withdrawal by self- and other beliefs in patients
with psychotic disorders (n =240). *p <.05, **p <.01, ***p <.001.
Negative Self-beliefs
Negative Other-Beliefs Child Physical Abuse
Positive Other-Beliefs
18 After adding positive and depressive symptoms to the model with, the mediation of positive other-beliefs lost its significance. The total model accounted for roughly 16% of the variance (R2 = .158, F(6,220) = 6.86, p <.001). The model of the direct effect accounted for roughly 12% of the variance (R2 = .118, F(3,223) = 9.92, p <.001). See Figure 3 for the regression
coefficients with positive symptoms as covariate and depressive symptoms as confounder. Positive symptoms were not related to positive other-beliefs (b = .01, p = .370).
b = .12 b = -.69 b = -4.52* (b’ = -3.51) b = .25** b = -.72 b = -.29 b = 2.50** b = -.32* b = -.33** b = -4.20**
Figure 3. Mediation between child physical abuse and social withdrawal by self- and other beliefs in patients
with psychotic disorders with positive symptoms included as covariate and depressive symptoms as confounder (n =227). *p <.05., ** p <.01.
3.4.2 Mediation model for child physical abuse in healthy controls
At last, the mediation of positive other-beliefs on the relation between physical abuse and social withdrawal was replicated in the healthy controls. Significant relations indicated an indirect effect of positive other-beliefs on the association between physical abuse and social withdrawal. Figure 4 shows the coefficients of all paths between the variables. This result remained after bootstrapping 95% CI [-9.18,-2.11]. The total model accounted for roughly 20% of the variance (R2 = .211, F(2,113) = 15.10, p <.001).
Negative Self-beliefs
Negative Other-Beliefs Child Physical Abuse
Positive Other-Beliefs Depressive Symptoms Positive Symptoms Social Withdrawal
19 b = -.81*** b = 6.41*** b = 12.80*** (b’ = -7.62*)
Figure 4. Mediation between child physical abuse and social withdrawal by positive other-beliefs in healthy
controls (n =116). *p <.05, ** p <.01, ***p <.001. b = -.40** b = -11.43*** b = -.66*** b = 3.57* b = -.20.30** b = -7.85** (b’ = -5.48)
Figure 5. Mediation between child physical abuse and social withdrawal by positive other-beliefs in healthy
controls with positive symptoms included as covariate and depressive symptoms as confounder (n =116). *p <.05, ** p <.01, ***p <.001.
The model of the direct effect accounted for roughly 11% of the variance (R2 = .108, F(1,114) = 13.76, p <.001). After adding depressive and positive symptoms as confounders to the model, the mediation lost its significance. The total model accounted for roughly 41% of the variance (R2 = .412, F(4,111) = 19.47, p <.001). The model of the direct effect accounted for roughly 38% of the variance (R2 = .383, F(3,112) = 23.20, p <.001). See Figure 5 for the
coefficients with depressive symptoms as confounder and positive symptoms as covariate. Positive symptoms were not related to positive other-beliefs (b = -.32 , p = .483).
4. Discussion
Previous studies indicated that patients with psychotic disorders who experienced CT show more social withdrawal compared to patients who did not experience CT(Boyda &
Positive Other-beliefs
Child Physical Abuse Social Withdrawal
Positive Other-beliefs
Child Physical Abuse Social Withdrawal
Positive Symptoms
Depressive Symptoms
20 McFeeters, 2015; Boyette et al., 2014; Stain et al., 2014). The current study tried to expand on previous findings to acquire more information about the relation between types of CT and social withdrawal and its mechanisms in patients with psychotic disorders.
First, the association between types of CT and social withdrawal was investigated in patients with psychotic disorders. As hypothesized higher frequency of physical abuse led to more social withdrawal. Additionally, emotional neglect was, as expected, not related to social withdrawal. Unexpectedly, physical neglect did also lead to more social withdrawal. Against the hypotheses, sexual abuse and emotional abuse were not related to social withdrawal. The multiple unexpected results might reflect the contradicting findings in previous studies(Bechdolf et al., 2010; Kraan et al., 2017; Thompson et al., 2014). Furthermore, the results show no obvious pattern of types of CT that increased the risk of psychosis, which made it hard to form expectations. According to Trauelsen et al. (2015), the effect of all types of CT altogether was larger than their individual effect. They implied that the effects of individual types of CT, like sexual abuse and emotional abuse, were lost due to inter-correlations between the types of CT. That could explain why several studies, including the current study, found different patterns of types of CT that increased the risk of psychosis or social withdrawal.
Second, relations between types of CT and self- and other-beliefs were examined in patients with psychotic disorders. As expected, the more physical abuse patients endured, the more negative other-beliefs and the less positive other-beliefs they had. Similarly emotional abuse was associated with more negative self-beliefs and emotional neglect was associated with less positive self-beliefs. Emotional neglect was associated with less positive self- and other-beliefs. Confirming the hypothesis, sexual abuse was not associated with any negative or positive self- and other-beliefs. Against the hypotheses, physical abuse was positively associated with negative self-beliefs and emotional abuse was not related to negative
other-21 beliefs and positive self- and other-beliefs. A previous study found that emotional neglect and physical neglect were associated with negative self-beliefs(Appiah-Kusi et al., 2017), the same results were expected to be found in the current sample. However, contrary to the findings of Appiah-Kusi et al. (2017), neither emotional neglect nor physical neglect were associated with negative self-beliefs. This contradiction could be explained by the differences in stages of the illnesses of the patients between the current study and the study of Appiah-Kusi et al. (2017). They investigated people with high risk for transitioning to psychosis. The patients with psychotic disorders who were examined in the current study were diagnosed at least six years in advance of the third assessment moment, which was used in the current study. At the first assessment moment, they could have been diagnosed ten years in advance. In total, patients could have been diagnosed with a psychotic disorder for 16 years. This long period of time could have given them the chance to learn to cope with their symptoms through medication and therapy, which might result in a decrease of negative self- and other-beliefs. Means of negative self- and other-beliefs were lower in the current study compared to others studies where people were more recently diagnosed. Fowler et al. (2006) found means of 1.20 for negative self-beliefs and 1.76 for negative other-beliefs. Taylor, Stewart and Dunn (2013) found means of 1.24 for negative self-beliefs and 1.84 for negative other-beliefs as to 0.50 for both negative self- and other beliefs in the current study. So both other populations scored much higher on negative beliefs.
The third research question was partly explorative and depended on results from research question 1 and 2, which resulted in physical abuse with negative self- and other-beliefs and positive-other other-beliefs as mediators. Only positive other-other-beliefs was found to have a negative indirect effect on the relation between physical abuse and social withdrawal in patients with psychotic disorders. However, after including positive and depressive symptoms in the mediation model, it lost significance. Depressive symptoms were found to be a
22 confounder and were associated with both positive other-beliefs and most strongly associated with social withdrawal. These findings are in line with Isvonaru et al. (2017). They suggested that types of CT are not directly associated with symptoms of psychosis, but proposed a network where symptoms of psychosis were mediated by general psychopathology, like depressive symptoms. Positive symptoms were found to be a covariate and only related to social withdrawal. Remarkably, negative self- and other-beliefs did not play a role in the mediation of the relation between physical abuse and social withdrawal. Although other studies did find negative beliefs to be mediators of the relation between CT and psychosis in people with an high risk of psychosis (Appiah-Kusi et al., 2017; Jaya et al., 2017) and in a student sample with psychotic symptoms(Gracie et al., 2007). However, in these three studies, participants had more negative beliefs compared to the participants in the current study. The severity of negative beliefs could play a significant role. To date, previous literature emphasized negative beliefs when exploring mechanisms of relations between CT and symptoms of psychosis. However, reduced positive other-beliefs also appear to be an underlying mechanism in the development of social withdrawal in patients with psychotic disorders who experienced physical abuse. Cognitive behavioral therapy was indicated to be an effective treatment for negative symptoms, like social withdrawal, in patients with psychotic disorders(Staring, Ter Huurne, & van der Gaag, 2013) and for depression(Excellence, 2009). A focus to improve self-beliefs was also found to be effective in reducing symptoms(Lecomte, Leclerc, & Wykes, 2017). We propose that future treatments would also try to improve positive other-beliefs to reduce social withdrawal in patients with psychotic disorders after experiencing physical abuse. Because depression confounded the mediation, improving positive other-beliefs through cognitive behavioral therapy could also help depressed patients to become less socially withdrawn.
23 At last the mediation by positive other-beliefs in the relation between physical abuse and social withdrawal was replicated in healthy controls. Similar results were found in the healthy controls. The sample of the healthy control group was smaller than in the patient group, which provides more support for the mediation model, because the false negative rate was higher. Thus, social withdrawal, after experiencing childhood physical abuse, is mediated by lower positive other-beliefs and depressive symptoms in both patients with psychotic disorders and healthy controls.
A limitation of the current study is that information was gathered at the third measurement moment of the GROUP study. As mentioned before, patients were diagnosed between six and sixteen years before the moment of assessment of the current study. For a long period of time, they could have had treatment and could have learned how to cope with psychosis, social withdrawal and self- and other-beliefs. So the used sample was not representative for all populations with psychotic disorders. Further, all measurements were self-report questionnaires, which are sensitive for biases. With CT it is possible that people don’t recall being abused. With social withdrawal and self- and other-beliefs, people can tend to answer socially desirable. Also, only frequency of CT was assessed, although it would also be interesting to know if participants felt traumatized after their CT. Some people can experience abuse and may not feel traumatized, while others do. That may have a whole different effect on self- and other-beliefs.
Follow-up studies could replicate the current study with total CT as measurement, to investigate if total amount of CT has more effect then types of CT individually with the mediation of self- and other-beliefs. Still, little underlying mechanisms of the relation between types of CT and social withdrawal is known and yet to be discovered. While positive other-beliefs and depressive symptoms may have an influence, other factors need to be
24 examined. For instance, more general psychopathology symptoms, like anxiety, could be included.
25 5. References
Abajobir, A. A., Kisely, S., Scott, J. G., Williams, G., Clavarino, A., Strathearn, L., & Najman, J. M. (2017). Childhood Maltreatment and Young Adulthood Hallucinations, Delusional Experiences, and Psychosis: A Longitudinal Study. Schizophr Bull. doi:10.1093/schbul/sbw175
Alemany, S., Goldberg, X., van Winkel, R., Gastó, C., Peralta, V., & Fañanás, L. (2013). Childhood adversity and psychosis: Examining whether the association is due to genetic confounding using a monozygotic twin differences approach. European
Psychiatry, 28(4), 207-212. doi:https://doi.org/10.1016/j.eurpsy.2012.03.001
Appiah-Kusi, E., Fisher, H. L., Petros, N., Wilson, R., Mondelli, V., Garety, P. A., . . . Bhattacharyya, S. (2017). Do cognitive schema mediate the association between childhood trauma and being at ultra-high risk for psychosis? J Psychiatr Res, 88, 89-96. doi:10.1016/j.jpsychires.2017.01.003
Association, A. P. (2000). Diagnostic and statistical manual of mental disorders (DSM-4,
revised): American Psychiatric Pub.
Barrowclough, C., Tarrier, N., Humphreys, L., Ward, J., Gregg, L., & Andrews, B. (2003). Self-esteem in schizophrenia: relationships between self-evaluation, family attitudes, and symptomatology. J Abnorm Psychol, 112(1), 92-99.
Bebbington, P. E., Bhugra, D., Brugha, T., Singleton, N., Farrell, M., Jenkins, R., . . . Meltzer, H. (2004). Psychosis, victimisation and childhood disadvantage: evidence from the second British National Survey of Psychiatric Morbidity. Br J Psychiatry, 185, 220-226. doi:10.1192/bjp.185.3.220
Bechdolf, A., Thompson, A., Nelson, B., Cotton, S., Simmons, M. B., Amminger, G. P., . . . Yung, A. R. (2010). Experience of trauma and conversion to psychosis in an
ultra-26 high-risk (prodromal) group. Acta Psychiatr Scand, 121(5), 377-384. doi:10.1111/j.1600-0447.2010.01542.x
Bentall, & Kaney, S. (1989). Content specific information processing and persecutory delusions: An investigation using the emotional Stroop test. British Journal of Medical
Psychology, 62(4), 355-364. doi:10.1111/j.2044-8341.1989.tb02845.x
Bentall, R. P., Wickham, S., Shevlin, M., & Varese, F. (2012). Do specific early-life adversities lead to specific symptoms of psychosis? A study from the 2007 the Adult Psychiatric Morbidity Survey. Schizophr Bull, 38(4), 734-740. doi:10.1093/schbul/sbs049
Bernstein, D. P., Stein, J. A., Newcomb, M. D., Walker, E., Pogge, D., Ahluvalia, T., . . . Desmond, D. (2003). Development and validation of a brief screening version of the Childhood Trauma Questionnaire. Child abuse & neglect, 27(2), 169-190.
Birchwood. (2003). Pathways to emotional dysfunction in first-episode psychosis. The British
journal of psychiatry, 182(5), 373-375. doi:10.1192/bjp.182.5.373
Birchwood, Smith, J., Cochrane, R., Wetton, S., & Copestake, S. (1990). The Social Functioning Scale. The development and validation of a new scale of social adjustment for use in family intervention programmes with schizophrenic patients. Br
J Psychiatry, 157, 853-859.
Boyda, D., & McFeeters, D. (2015). Childhood maltreatment and social functioning in adults with sub-clinical psychosis. Psychiatry Res, 226(1), 376-382. doi:10.1016/j.psychres.2015.01.023
Boyette, L. L., van Dam, D., Meijer, C., Velthorst, E., Cahn, W., de Haan, L., . . . Myin-Germeys, I. (2014). Personality compensates for impaired quality of life and social functioning in patients with psychotic disorders who experienced traumatic events.
27 Excellence, N. I. f. C. (2009). Depression in adults: The treatment and management of
depression in adults. London: NICE.
Fisher, H. L., Jones, P. B., Fearon, P., Craig, T. K., Dazzan, P., Morgan, K., . . . Morgan, C. (2010). The varying impact of type, timing and frequency of exposure to childhood adversity on its association with adult psychotic disorder. Psychol Med, 40(12), 1967-1978. doi:10.1017/s0033291710000231
Fowler, D., Freeman, D., Smith, B., Kuipers, E., Bebbington, P., Bashforth, H., . . . Garety, P. (2006). The Brief Core Schema Scales (BCSS): psychometric properties and associations with paranoia and grandiosity in non-clinical and psychosis samples.
Psychol Med, 36(6), 749-759. doi:10.1017/s0033291706007355
Frissen, A., Lieverse, R., Drukker, M., van Winkel, R., & Delespaul, P. (2015). Childhood trauma and childhood urbanicity in relation to psychotic disorder. Soc Psychiatry
Psychiatr Epidemiol, 50(10), 1481-1488. doi:10.1007/s00127-015-1049-7
Garety, P. A., Kuipers, E., Fowler, D., Freeman, D., & Bebbington, P. (2001). A cognitive model of the positive symptoms of psychosis. Psychological medicine, 31(02), 189-195.
Gracie, A., Freeman, D., Green, S., Garety, P. A., Kuipers, E., Hardy, A., . . . Fowler, D. (2007). The association between traumatic experience, paranoia and hallucinations: a test of the predictions of psychological models. Acta Psychiatr Scand, 116(4), 280-289. doi:10.1111/j.1600-0447.2007.01011.x
Hafner, H., Loffler, W., Maurer, K., Hambrecht, M., & an der Heiden, W. (1999). Depression, negative symptoms, social stagnation and social decline in the early course of schizophrenia. Acta Psychiatr Scand, 100(2), 105-118.
Hansen, C. F., Torgalsboen, A. K., Melle, I., & Bell, M. D. (2009). Passive/apathetic social withdrawal and active social avoidance in schizophrenia: difference in underlying
28
psychological processes. J Nerv Ment Dis, 197(4), 274-277.
doi:10.1097/NMD.0b013e31819dbd36
Hardy, A., Emsley, R., Freeman, D., Bebbington, P., Garety, P. A., Kuipers, E. E., . . . Fowler, D. (2016). Psychological Mechanisms Mediating Effects Between Trauma and Psychotic Symptoms: The Role of Affect Regulation, Intrusive Trauma Memory, Beliefs, and Depression. Schizophr Bull, 42(suppl_1), S34-S43. doi:10.1093/schbul/sbv175
Hayes, A. F. (2012). PROCESS: A versatile computational tool for observed variable mediation, moderation, and conditional process modeling: University of Kansas, KS. Heins, M., Simons, C., Lataster, T., Pfeifer, S., Versmissen, D., Lardinois, M., . . .
Myin-Germeys, I. (2011). Childhood trauma and psychosis: a case-control and case-sibling comparison across different levels of genetic liability, psychopathology, and type of trauma. Am J Psychiatry, 168(12), 1286-1294. doi:10.1176/appi.ajp.2011.10101531 Hirschfeld, R., Montgomery, S. A., Keller, M. B., Kasper, S., Schatzberg, A. F., Möller, H.-J.,
. . . Versiani, M. (2000). Social functioning in depression: a review. The Journal of
clinical psychiatry.
James, A. V., Hasson-Ohayon, I., Vohs, J., Minor, K. S., Leonhardt, B. L., Buck, K. D., . . . Lysaker, P. H. (2016). Metacognition moderates the relationship between dysfunctional self-appraisal and social functioning in prolonged schizophrenia independent of psychopathology. Compr Psychiatry, 69, 62-70. doi:10.1016/j.comppsych.2016.05.008
Janssen, I., Krabbendam, L., Bak, M., Hanssen, M., Vollebergh, W., de Graaf, R., & van Os, J. (2004). Childhood abuse as a risk factor for psychotic experiences. Acta Psychiatr
29 Jaya, E. S., Ascone, L., & Lincoln, T. M. (2017). Social Adversity and Psychosis: The
Mediating Role of Cognitive Vulnerability. Schizophr Bull, 43(3), 557-565. doi:10.1093/schbul/sbw104
Kay, S. R., Flszbein, A., & Opfer, L. A. (1987). The positive and negative syndrome scale (PANSS) for schizophrenia. Schizophr Bull, 13(2), 261.
Kay, S. R., Opler, L. A., & Lindenmayer, J.-P. (1988). Reliability and validity of the positive and negative syndrome scale for schizophrenics. Psychiatry research, 23(1), 99-110. Kesting, M. L., & Lincoln, T. M. (2013). The relevance of self-esteem and self-schemas to
persecutory delusions: a systematic review. Compr Psychiatry, 54(7), 766-789. doi:10.1016/j.comppsych.2013.03.002
Kilcommons, A. M., & Morrison, A. P. (2005). Relationships between trauma and psychosis: an exploration of cognitive and dissociative factors. Acta Psychiatr Scand, 112(5), 351-359. doi:10.1111/j.1600-0447.2005.00623.x
Konings, M., Bak, M., Hanssen, M., van Os, J., & Krabbendam, L. (2006). Validity and reliability of the CAPE: a self-report instrument for the measurement of psychotic experiences in the general population. Acta Psychiatr Scand, 114(1), 55-61. doi:10.1111/j.1600-0447.2005.00741.x
Korver, N., Quee, P. J., Boos, H. B., Simons, C. J., & de Haan, L. (2012). Genetic Risk and Outcome of Psychosis (GROUP), a multi-site longitudinal cohort study focused on gene-environment interaction: objectives, sample characteristics, recruitment and assessment methods. Int J Methods Psychiatr Res, 21(3), 205-221. doi:10.1002/mpr.1352
Kraan, T. C., Velthorst, E., Themmen, M., Valmaggia, L., Kempton, M. J., McGuire, P., . . . van der Gaag, M. (2017). Child Maltreatment and Clinical Outcome in Individuals at
30 Ultra-High Risk for Psychosis in the EU-GEI High Risk Study. Schizophr Bull. doi:10.1093/schbul/sbw162
Lecomte, T., Leclerc, C., & Wykes, T. (2017). Symptom fluctuations, self-esteem, and cohesion during group cognitive behaviour therapy for early psychosis. Psychol
Psychother. doi:10.1111/papt.12139
Read, J., Agar, K., Argyle, N., & Aderhold, V. (2003). Sexual and physical abuse during childhood and adulthood as predictors of hallucinations, delusions and thought disorder. Psychol Psychother, 76(Pt 1), 1-22. doi:10.1348/14760830260569210
Read, J., van Os, J., Morrison, A. P., & Ross, C. A. (2005). Childhood trauma, psychosis and schizophrenia: a literature review with theoretical and clinical implications. Acta
PsychiatrScand, 112(5), 330-350. doi:10.1111/j.1600-0447.2005.00634.x
Rubino, I. A., Nanni, R. C., Pozzi, D. M., & Siracusano, A. (2009). Early adverse experiences in schizophrenia and unipolar depression. J Nerv Ment Dis, 197(1), 65-68.
doi:10.1097/NMD.0b013e3181925342
Shevlin, M., Dorahy, M. J., & Adamson, G. (2007). Trauma and psychosis: an analysis of the National Comorbidity Survey. Am J Psychiatry, 164(1), 166-169. doi:10.1176/ajp.2007.164.1.166
Siegrist, K., Millier, A., Amri, I., Aballea, S., & Toumi, M. (2015). Association between social contact frequency and negative symptoms, psychosocial functioning and quality of life in patients with schizophrenia. Psychiatry Res, 230(3), 860-866. doi:10.1016/j.psychres.2015.11.039
Spence, W., Mulholland, C., Lynch, G., McHugh, S., Dempster, M., & Shannon, C. (2006). Rates of childhood trauma in a sample of patients with schizophrenia as compared
31 with a sample of patients with non-psychotic psychiatric diagnoses. J Trauma
Dissociation, 7(3), 7-22. doi:10.1300/J229v07n03_02
Stain, H. J., Bronnick, K., Hegelstad, W. T., Joa, I., Johannessen, J. O., Langeveld, J., . . . Larsen, T. K. (2014). Impact of interpersonal trauma on the social functioning of adults with first-episode psychosis. Schizophr Bull, 40(6), 1491-1498. doi:10.1093/schbul/sbt166
Staring, A. B., Ter Huurne, M. A., & van der Gaag, M. (2013). Cognitive Behavioral Therapy for negative symptoms (CBT-n) in psychotic disorders: a pilot study. J Behav Ther
Exp Psychiatry, 44(3), 300-306. doi:10.1016/j.jbtep.2013.01.004
Taylor, H. E., Stewart, S. L., Dunn, G., Parker, S., Fowler, D., & Morrison, A. P. (2014). Core schemas across the continuum of psychosis: a comparison of clinical and non-clinical groups. Behav Cogn Psychother, 42(6), 718-730. doi:10.1017/s1352465813000593 Thombs, B. D., Bernstein, D. P., Lobbestael, J., & Arntz, A. (2009). A validation study of the
Dutch Childhood Trauma Questionnaire-Short Form: factor structure, reliability, and known-groups validity. Child Abuse Negl, 33(8), 518-523. doi:10.1016/j.chiabu.2009.03.001
Thombs, B. D., Lewis, C., Bernstein, D. P., Medrano, M. A., & Hatch, J. P. (2007). An evaluation of the measurement equivalence of the Childhood Trauma Questionnaire--Short Form across gender and race in a sample of drug-abusing adults. J Psychosom
Res, 63(4), 391-398. doi:10.1016/j.jpsychores.2007.04.010
Thompson, A. D., Nelson, B., Yuen, H. P., Lin, A., Amminger, G. P., McGorry, P. D., . . . Yung, A. R. (2014). Sexual trauma increases the risk of developing psychosis in an ultra high-risk "prodromal" population. Schizophr Bull, 40(3), 697-706. doi:10.1093/schbul/sbt032
32 Trauelsen, A. M., Bendall, S., Jansen, J. E., Nielsen, H. G., Pedersen, M. B., Trier, C. H., . . . Simonsen, E. (2015). Childhood adversity specificity and dose-response effect in non-affective first-episode psychosis. Schizophr Res, 165(1), 52-59. doi:10.1016/j.schres.2015.03.014
van Dam, D. S., van Nierop, M., Viechtbauer, W., Velthorst, E., van Winkel, R., Bruggeman, R., . . . Wiersma, D. (2015). Childhood abuse and neglect in relation to the presence and persistence of psychotic and depressive symptomatology. Psychol Med, 45(7), 1363-1377. doi:10.1017/s0033291714001561
Varese, F., Smeets, F., Drukker, M., Lieverse, R., Lataster, T., Viechtbauer, W., . . . Bentall, R. P. (2012). Childhood adversities increase the risk of psychosis: a meta-analysis of patient-control, prospective- and cross-sectional cohort studies. Schizophr Bull, 38(4), 661-671. doi:10.1093/schbul/sbs050
Velthorst, E., Nieman, D. H., Becker, H. E., van de Fliert, R., Dingemans, P. M., Klaassen, R., . . . Linszen, D. H. (2009). Baseline differences in clinical symptomatology between ultra high risk subjects with and without a transition to psychosis. Schizophr
Res, 109(1-3), 60-65. doi:10.1016/j.schres.2009.02.002
White, R., Bebbington, P., Pearson, J., Johnson, S., & Ellis, D. (2000). The social context of insight in schizophrenia. Soc Psychiatry Psychiatr Epidemiol, 35(11), 500-507.
