Masterthese
Rigid thinking style
and Cognitive
Remediation
Therapy in anorexia
nervosa restrictive
and binge-purge
type patients
Van Geffen, E.J. (Lisanne)
5946662
Begeleiders
Watson, A.J.B. Universiteit van Amsterdam
Danner, U.N.
Altrecht Eetstoornissen Rintveld
Abstract
Objective The first purpose of this study is to examine set-shifting and central coherence
ability in both restrictive (ANR) and binge-purge type anorexia nervosa (ANBP) patients. Second, we will explore to what extent thinking style is of influence on the effectiveness in terms of quality of life of Cognitive Remediation Therapy – a treatment module that aims to improve cognitive flexibility.
Method Seventy-three female patients with AN participated in this study, 46 with ANR and
27 with ANBP. In order to measure their thinking style, the following assessment was conducted; Trail Making Test, Wisconsin Card Sorting Test, Rey Complex Figure Test and The Multidimensional Perfectionism Scale. The Eating Disorder Quality of Life questionnaire was used to measure quality of life. Linear mixed models were used to measure moderating effects on the effectiveness of CRT.
Results Patients with ANBP had significant weaker central coherence and a tendency to have
poorer set-shifting abilities and more perfectionism. Set-shifting ability at the start of CRT was of influence on the effectiveness in terms of quality of life, whilst type of AN had no moderating effect.
Discussion Further research should focus on neuropsychological performance in both AN
diagnostic subtypes and investigate the probable existence of a more rigid subgroup within AN. This investigation could lead to more personalized use and development of treatments that might lead to better treatment outcomes.
Keywords Anorexia Nervosa, Anorexia Nervosa restrictive, Anorexia Nervosa binge-purge,
Introduction
Anorexia nervosa is characterized by persistent stereotyped or perseverative behavior (e.g. ritualized eating behavior at meal times) and obsessions (e.g. calorie counting), which strongly affect the physical condition and quality of life of patients with AN, including work performance and social relationships (1-3). Their rigid behavior is often not only specifically related to mealtimes or to the state of their illness, but is also visible in a variety of aspects such as their personality, but also in their process of thinking (2). In general, AN patients have a strong tendency to focus on details and seem less able to consider alternatives to a current situation or innovative solutions to a problem (4). It is suggested that this tendency of rigid thinking found in AN are a result of neuropsychological inefficiencies, in particular, poor mental flexibility, i.e. set-shifting (5), and weak global processing, i.e. central coherence, (6). It is thought that these inefficiencies are an important factor in the development, maintenance and recovery of AN (2, 3, 7, 8) and therefore need to be addressed in order for any treatment to be effective (9).
Anorexia nervosa subtypes
Research repeatedly reports set-shifting (5) and central coherence (6) inefficiencies in all individuals with AN compared to healthy controls. However, despite important behavioral and personality differences, only few studies examine if these differences can also be found in the thinking styles of AN restrictive (ANR) and binge-purging type patients (ANBP) (5, 10-14). For instance, individuals with ANBP have a more impulsive personality than individuals with ANR and are inclined to behave more impulsively when confronted with a negative affective state (15, 16). Differences in cognitive functioning that have been reported, have to do with for example decision-making (17, 18), in which ANR seems to have an inability to produce an advantageous long-term strategy and ANBP do neither have a clear advantageous or a clear disadvantageous behavioral strategy (18). It is reported that solely in the ANBP group higher impulsivity leads to more decision making impairments (19). Further, ANBP is associated with poorer quality of life (20). The few studies that focused on differences in thinking styles between patients with ANBP and ANR report inconsistent findings. Some authors found increased set-shifting problems in ANBP compared to ANR patients (5, 11, 12) whereas other studies did not find any significant difference (10, 13, 14). The only study that examined central coherence strength between AN subtypes, reports
weaker central coherence in ANR compared to ANBP (10). More knowledge about the
neuropsychological abilities of both AN subtypes is needed, since insight could lead to a more personalized and effective use of treatments and to a more focused development of new treatments or refinement of current ones. Which is of utmost importance, considering current treatments for AN patients are insufficient effective and patients are suffering severely from the disorder both mentally and physically (21).
Cognitive Remediation Therapy (CRT)
Rigid thinking styles are considered to be important factors hindering treatment to be effective (9). Impaired cognitive flexibility and inefficiencies to oversee the bigger picture, tends to make it difficult to internalize therapeutic insights and implement them into daily
life. Cognitive rigidity is also a characteristic of other mental illnesses. It is known from literature in e.g. schizophrenia (22) and brain injury (21) that cognitive remediation therapy (CRT) is an effective strategy for teaching new cognitive skills relevant for everyday functioning and it improves clinical outcomes (9). Therefore, Tchanturia and colleges (23) adapted and tailored CRT for AN to use it as a treatment module. This module targets processes of thinking rather than the content of thinking. It includes exercises to improve cognitive flexibility, central coherence, enhancing self-reflection, challenging perfectionistic tendencies, exploring alternative cognitive strategies and practicing behavioral tasks in everyday life (9).
Studies are currently being done on the effectiveness of CRT for patients with eating disorders and first evidence shows that CRT for AN patients is effective (24). A few randomized controlled trails (RCTs) have been conducted (25-28) and the outcomes suggest improved neuropsychological performance after CRT (26, 28). Subsequently, two studies found improvement in several clinical aspects, including reduced depressive symptoms (28), increased quality of life (29) and even decreased eating disorders psychopathology (29). This latter finding is remarkable considering that CRT is not directly aimed at improving eating disorder pathology. Another interesting finding of Dingemans and colleagues (29) is that patients with poor baseline set-shifting abilities benefitted significantly more from CRT in terms of quality of life, than patients with relatively good baseline set-shifting abilities. This seems to suggest that CRT is particularly effective for individuals with a more rigid thinking style.
An important note is that the study of Dingemans et al. (29) contained ANR, ANBP as well as BN patients and no attention was devoted to differentiate between eating disorder subtypes. ANBP and BN patients have similarities (30), however, also important dissimilarities are known, e.g. impaired decision making are associated with memory deficits in AN and elevated sensitivity to reward as opposed to punishment in BN (31). Also they differ in cognitive flexibility as been shown different performance on several tests, however the differential causes are still unclear (13).
In this study we will first investigate if differences in thinking style exist between ANR and ANBP patients. Based on prior research we hypothesize that ANBP will have worse set-shifting performance and ANR will have worse central coherence. These results will lead to the second part of this study, in which we will explore the extent in which dissimilarities between ANR and ANBP in baseline thinking style is of influence on the effectiveness of CRT in terms of quality of life. It is expected that patients with worse cognitive performance would benefit the most of CRT. Since CRT focuses on improving cognitive flexibility and this improvement might make patients more susceptible to treatment that focus on decreasing eating disordered behavior.
Method
Participants
Seventy-three female patients with AN participated in this study, 46 with a DSM-IV (26) diagnoses of ANR and 27 with ANBP. AN diagnoses were ascertained by ED experts (all medical doctors) and confirmed with the Eating Disorders Examination (32) or Eating
Disorders Examination Questionnaire (33). The patients were treated at Altrecht Eating Disorders Rintveld or the Centre for Eating Disorders Ursula, both specialized centers for the treatment of ED in the Netherlands. Exclusion criteria were a) psychotic disorder according to DSM-IV, b) use of medication, unless receiving a stable dose, c) developmental mental disorder or known brain damage, or d) substance abuse according to DSM-IV. All participants were thoroughly informed about the research procedure and signed informed consent. The study was approved by the Medical Ethics Committee for Mental Health Institutions (METIGG) and local approval from the Committee Scientific Research of Altrecht Mental Health Institute.
Neuropsychological instruments
Trail Making Test. A computerized version of the Trail Making Test (TMT) (34) was
used to measure set-shifting. This task consists of two parts, during both parts the participant is instructed to connect a set of 25 dots as fast as possible. The first part consist of solely a numeric sequence (Trail A 1-2-3 etc), the second part of an numeric and alphabetical sequence combined requiring set shifting (Trail B 1-A-2-B-3-C etc). The outcome measure is defined as the difference in reaction time between part B minus part A (in seconds). Higher score reflects more set-shifting deficits.
Wisconsin Card Sorting Test. Also a computerized version of the Wisconsin Card
Sorting Task (WCST) (35) was used to measure set-shifting, in particular to measure perseveration when shifting from one set to another. The participant is instructed to match a stimulus card with one of four category cards. The participant is not informed about the rules on which the cards need to be categorized. After each try the participant receives feedback if the correct rule was applied. After 10 consecutive correct answers, the rule changes without notice and participants have to find the new rule. An incorrect answer is considered perseverative when a card is categorized according to the previous rule. The test ended when the participant either completed all nine categories or finished all the 128 cards, which varies in color (green, red, blue, yellow), number (one to four), and symbol (triangles, crosses, starts, or circles). The number of perseverative errors was used as a measure of set-shifting ability.
Rey Complex Figure Test. The pen and pencil version of the Rey-Osterrieth Complex
Figure Test (36) was used, in which participants are asked to copy a complex figure. The order of construction and style were measured according to Booth’s scoring system (37). The construction score is the order in which the elements of the figure were drawn. The participants will receive higher score if they start withdrawing the main constructs of the figure, e.g. the main rectangle, and not the smaller details. The style reflects the continuity of drawing, in which a participant will receive higher score when continuing drawing the subfigures as a whole without interruption. The interruptions reflect that the patients have not seen the subfigure as a whole. The Central Coherence Index (CCI) is the mean score of the order of construction and the style score. A lower score reflects a weaker central coherence.
Clinical and descriptive instruments
The Eating Disorder Quality of Life (38). The main outcome measure of this study is
disease-specific instruments has good psychometric properties and is more sensitive than generic health related quality of life instruments (31). It consists of a 25 items (rank 0-4) divided into four subscales; Psychological, Physical/Cognitive, Financial, and Work/School. In this study the overall mean scale was used, in which lower scores reflect a higher quality of life. The instrument shows high internal consistency (Cronbach’s alpha = 0.93) on each question and also a good internal reliability of each domain (39).
The Multidimensional Perfectionism Scale. Level of perfectionism was measured by
two subscales of the Multidimensional Perfectionism Scale (MPS) (40), namely subscales
‘concern over mistakes’ and ‘doubts about actions’ since these are almost exclusively
associated with AN and not generically predictive of psychopathology (41). This is of interest since both are suggested include obsessive behavior and to be unhealthy aspects of perfectionism (42). Higher scores reflect more perfectionism.
The Eating Disorders Examination Questionnaire (43). The main score of the Eating
Disorders Examination Questionnaire (EDEQ) was used to measure the level of eating disorder pathology. A higher score reflects more psychopathology (range 0-6).
Furthermore, questions regarding age, highest level of education, duration of illness, and age of onset were asked and BMI (kg/m2) was determined using the Tanita body composition analyzer TBF-300 (Tanita Corporation, Tokyo, Japan).
Procedure
This study was part of a larger study evaluating the feasibility of CRT for severe or enduring eating disorders. Intervention details have been described previously in Dingemans et al. (29).
The present study consisted of two parts: the first part examined differences in thinking styles of patients with ANBP compared to patients with ANR by testing performance on the neuropsychological tests prior to the start of CRT treatment (part A). The purpose of the second part was to explore the extent in which differences between ANR and ANBP patients in neuropsychological performance is of influence on the effectiveness of CRT in terms of quality of life (part B). This part is designed as a Randomized Controlled Trial, with the experimental condition receiving CRT next to TAU. The assessors had no therapeutic relationship with any of the participants and were blind to the group assignment. The EDQOL was repeatedly measured; at baseline (T0), after 6 weeks (end of CRT or six weeks of TAU) (T1) and after six months (T2).
Statistical analyses
The analyses were done using Statistical Package for the Social Sciences (SPSS) version 20.0. Analyses of variance (ANOVA) and Chi – Square Tests were used to compare the demographic and clinical characteristics between restrictive ANR and ANBP patients.
Part A (thinking styles of AN subtypes). ANOVAs were used to compare the outcome on
neuropsychological tests between subtypes. We did not correct for BMI or age of onset since it is known these factors do not affect neuropsychological performance (44). Since some of the outcomes were not normally distributed, all neuropsychological data were transformed using square root transformations before ANOVAs were done. For interpretation purposes,
untransformed data are presented in the tables. Pearson correlations were calculated to determine correlations between neuropsychological variables and clinical characteristics.
Part B (influence of thinking style on CRT). To explore the effect of AN subtypes and
thinking style on CRT in terms of quality of life, linear mixed models were used. Since the repeated measurements were hierarchically structured with measurement occasions nested within individuals. This approach has two advantages that are noteworthy. First, under the assumption that the data are “missing at random”, missing data do not have to be imputed. The multilevel model can simply be estimated on the basis of the available data using the full maximum likelihood approach. Second, it allows individual variation in intercepts and/or regression slopes, since it is possible to model random variation for estimated parameters. Time contrasts were created by means of dummy coding (T0-T1, T0-T2) in order to investigate the moderators of short- and long-term treatment response. The continuous moderator variables were standardized (45).
Results
Participants
Demographic and clinical characteristics are displayed in Table 1. ANR and ANBP patients were comparable in age, level of education, duration of illness, eating pathology and quality of life, but differed in BMI and age of onset: patients with ANBP had a higher BMI and a lower age of onset than patients with ANR.
A) Thinking styles of AN subtypes
Results (see Table 1) demonstrated significant weaker central coherence in ANBP than in ANR patients on the central coherence index of the RCFT. Furthermore, ANBP patients reported more doubts about actions (MPS) than ANR patients and a trend significant difference in number of perseverative errors (WCST) was found: ANBP patients made slightly more errors (worse set shifting) than ANR patients. Correlation analyses showed a positive correlation between perseverative errors (WCST) and TMT performance in ANBP patients, r = .46, p = .02. In addition, the perfectionism scale ‘concerns about mistake’ was positively correlated with the subscale ‘doubt about actions’ in both subtypes, ANR r = .47, p < .001, ANBP r = .44, p < .03, and with quality of life in ANR women, r = .54, p < .001. These findings indicate that higher perfectionism is related to worse quality of life in ANR patients.
To sum up, women with ANBP in this study displayed a more rigid thinking style than women with ANR.
B) Influence thinking style on CRT in terms of quality of life
The first model to investigate quality of life improvements over time, included condition. Results demonstrated a similar improvement in quality of life in both conditions (TAU only
and TAU + CRT), as evident by significant time effects between T0-T2 (β = -0.34 (0.09), t
(131.38) = -3.93, p < .001). After six weeks of treatment (T1), the CRT group showed significant more improvement in quality of life than the TAU group, as evident by the
significant 2-way interaction effect of condition and time (T0-T1) (β = -0.30 (0.12), t (130.54) = -2.44, p = .02).
Since differences in thinking styles between AN subtypes were found (see part A), the next question was if CRT is similarly effective in terms of improvement in quality of life for both ANR and ANBP patients. In this model we added AN subtype. The results showed that there is no significant difference in effectiveness of CRT between the AN subtypes, see Table 2.
Subsequently, we investigated the moderating effect of the neuropsychological measures separately. We excluded AN subtype in the model and added the neuropsychological measures in separate models. There was no moderating effect of perseverative errors (WCST), central coherence index (RCFT), concerns about mistakes (MPS) or doubt about actions (MPS), see Table 2. However, main effects of MPS concerns about mistakes and MPS doubt about actions were found, which indicates that level op perfectionism is of influence of quality of life.
A significant 3-way interaction effect of time (T0-T2), condition and TMT performance was found, showing a moderating effect of set shifting on quality of life. Further examination of this effect revealed that in the CRT group, women with poorer set-shifting (TMT) reported stronger improvement in quality of life than women with relative good set-shifting (TMT) abilities. This effect was not found in the TAU only condition.
Taken together, the present findings revealed that effectiveness of CRT on quality of life is not dependent on AN subtype diagnoses, but set shifting ability is of influence.
Discussion
The purpose of this study was to test differences in thinking style between the AN subtypes and to explore if effectiveness of CRT in terms of quality of life improvement was moderated by these differences. Thinking styles is a way of describing how a individual thinks, e.g. solves problems, makes decisions or perceive information. Neuropsychological studies have highlighted a tendency in AN to have a rigid thinking style (2, 3). This rigid thinking style is reflected in the rituals and obsessive behavior among food, and is also visible in their process of thinking. It is suggested that this is a results of neuropsychological inefficiencies, e.g. central coherence (6) and set-shifting inabilities (5) (44).
This study shows that ANBP have weaker central coherence than ANR. This is in contrast to Autreve et al. (10), who found weaker central coherence problems in ANR. When taken into account the (behavioral) differences, e.g. more impulsivity in ANBP (15, 16), altered decision-making patterns (18), more co morbidities (30) and lower quality of life (20), it seems likely that ANBP have more neuropsychological difficulties. For example, when not being able to see the bigger picture, one can suggest that it is more difficult to make decisions based on long-term benefits, when one does not have a clear overview of those benefits. Therefore, is probable that weak central coherence is associated with decisions based on more short-term benefits, e.g. binge-purge behavior. Furthermore, a tendency was found showing patients with ANBP to have stronger perfectionism, in particular doubt about actions, and more set-shifting inefficiencies. This underlings the hypothesis that ANBP have more neuropsychological difficulties resulting in a more rigid thinking style, as in accordance to some prior research (5, 46), but not all. As mentioned, Autreve et al. (10) found weaker
central coherence in ANR. This might be due to methodological difference. Autreve et al. made use of the Object Assembley, whereas in this study the RCFT was used. The Object Assembley is a task in which the participant is asked to complete a puzzle. In contrast to the RCFT, spatial awareness is needed in order to successfully complete the task. Another difference is that participants conducting the Object Assembley are aware that their ability to integrate information and oversee the bigger picture is measured, since participants are asked to integrate different puzzle pieces into one figure, whereas in the RCFT central coherence is a relative simple task that measure central coherence without the patient’s awareness. Since AN patients are tend to be perfectionistic, tasks measuring central coherence without awareness might be less biased by increasing tension.
A rigid thinking style might result in an inability to fully engage in therapy in which changing behavioral and thinking patterns is essential (9). CRT is a treatment module that aims to improve cognitive flexibility and might be the most beneficial preceding therapy aimed at the content of thinking (23). We have investigated to what extent baseline thinking style has an influence of the effectiveness of CRT in terms of quality of life. This study shows that patients who received CRT have more improved quality of life after six weeks of treatment than patients who only received TAU. Further, we found that patients with poorer baseline set-shifting benefit more of CRT in term of quality of life after six weeks of CRT compared to TAU only. Remarkably, there was no moderating effect of AN subtype, despite baseline differences in thinking style. This could be due to the fact that the number of participants was rather small to perform these linear mixed model analyses (45), so potential moderators could have been missed due to limited power. However, it could also be that we should not focus on AN subtype in particular, but devote more attention to neuropsychological functioning. Prior research of Danner et al. (17) has found a correlation between poor set-shifting and weak central coherence in both ill and recovered AN patients, which implies that some patients but not all, experience rigid behavior. In the current study we found a correlation between perseverative errors and TMT performance, but only in ANBP patients, which seems to underlie the suggestion that a (more) rigid subgroup within AN exists. This subgroup might be more present in ANBP than in ANR, considering the found difference in thinking style.
More research on neuropsychological functioning of AN subtypes or of clinical subgroups more generally are of great importance, especially when taken into account treatment effectiveness. At this moment many patients do not fully recover of AN despite commitment to (several) treatments (21). Insight in differences between AN subtype or specific rigid subgroup is an essential link to develop tailored treatments in order to improve outcome. This could also lead to a more focused development of current treatments. For instance, our findings support the idea of Autreve et al. (2013) that both AN subtype might need a different CRT approach, in that ANR patients will benefit less from remediation strategies focusing on the enhancement of global processing compared to ANBP since their baseline thinking style seems to be better. On the contrary, research implies cognitive empathy difficulties within ANR (47). Thus, ANR might benefit more of strategies that improve the ability to take another person’s perspective.
Concluding, this study shows that ANR and ANBP differ in cognitive performance prior to treatment, in which ANBP tends to have a more rigid thinking style. In addition, this
study suggests that thinking style moderates the effectiveness of CRT treatment in terms of quality of life. It is implied that further research should focus on neuropsychological performance in both AN diagnostic subtypes and investigate the probable existence of a more rigid subgroup within AN. This investigation could lead to the development of more tailored treatments and so might enhance treatment outcome.
Appendix
Table 1. Mean (and SD) of demographics and clinical characteristics per group (ANR woman and ANBP woman); eating disorder pathology (EDE-Q); quality of life (EDQOL), and mean (and SD) of neuropsychological measurements; set-shifting (WCST, perseverative errors and TMT Part B – Part A), central coherence ( RCFT, Central Coherence Index) and perfectionism (MPS concerns about mistakes and MPS doubt about actions) as well as group differences. ANR ANBP N = 46 N = 27 Mean SD Mean SD F p η2 Age 27.37 9.14 26.81 7.42 0.71 .79 Education 4.91 1.98 4.73 2.05 5.00 .71 BMI 15.43 2.00 16.62 2.33 5.07 .03 .07 Illness duration 8.75 8.41 10.71 6.46 0.98 .33 Age of onset 18.80 7.44 15.16 2.27 5.64 .02 .08 EDE-Q 3.93 1.39 4.42 0.89 2.71 .10 EDQOL 0.49 0.25 0.59 0.23 2.49 .12 WCST Perseverative error 16.72 1.70 22.67 3.02 3.11 .08 TMT 23.39 23.50 24.48 19.90 .04 .84 RCFT
Central coherence index 1.85 0.05 1.68 0.05 0.66 .02 .07
MPS cam 3.86 0.73 4.03 0.57 1.04 .31
MPS daa 3.72 0.76 4.04 0.66 3.22 .08
Note: EDE-Q = Eating Disorder Examination Questionnaire; EDQOL= Eating Disorder
Quality of Life ; WSCT = Wisconsin Card Sorting Test; RCFT = Rey Complex Figure Test; TMT = Trail Making Test; MPS = Multidimensional Perfectionism Scale
Table 2. Multilevel test scores of EDQOL, with time points T0 (baseline), T1 (6-weeks) and T2 (6-months); condition: TAU or TAU+CRT; measurement referring to the left column, subtype of anorexia nervosa (AN subtype) set-shifting (WCST, perseverative errors and TMT Part B – Part A), central coherence (RCFT, Central Coherence Index) and perfectionism (MPS concerns about mistakes and MPS doubt about actions).
EDQOL Measurement
β (SE),t-tests
3-way interaction
Time x condition x measurement
β (SE),t-tests T0 vs. T1 T0 vs. T2 AN subtype -0.29(0.11), t(87.98) = 2.52 ** -0.19 (0.16), t(162.05) = -1.16 -0.21 (0.17), t(161.45) = -1.25 WCST Perseverative errors 0.02 (0.07), t(85.66) = 0.35 -0.09 (0.08), t(156.63) = -1.19 0.09 (0.08), t(156.39) = 1.09 RCFT
Central Coherence Index
-0.07 (0.06), t(83.69) = -1.24 0.06 (0.09), t(164.13) = 0.61 0.01 (0.10), t(163.20) = 0.09 TMT Part B – Part A 0.03 (0.06), t(88.51) = 0.54 -0.03 (0.07), t(155.15) = -0.39 -0.19 (0.08), t(154.91) = -2.54** MPS
concerns about mistakes
0.19(0.05), t(90.47) = 3.63*** 0.01 (0.08), 0.02 t(166.78) = 0.17 -0.08 (0.08), t(166.47) = -1.0 MPS
doubts about actions
0.15 (0.05), t(83.63) = 2.72** 0.05(0.09), t(169.64) = 0.57 -0.10 (0.10), t(167.52) = -1.02
Note: EDQOL= Eating Disorder Quality of Life ; WSCT = Wisconsin Card Sorting Test; RCFT = Rey Complex Figure Test; TMT = Trail
Making Test; MPS = Multidimensional Perfectionism Scale ** p < .01
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