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7/24/2019 Schizophr Bull 2014 Mehl 1338 46

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Schizophrenia Bulletinvol. 40 no. 6 pp. 13381346, 2014

doi:10.1093/schbul/sbu040

Advance Access publication April 17, 2014

The Author 2014. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved.For permissions, please email: [email protected]

Why Do Bad Things Happen to Me? Attributional Style, Depressed Mood, andPersecutory Delusions in Patients With Schizophrenia

Stephanie Mehl*,1,2, Martin W. Landsberg2, Anna-Christine Schmidt2, Maurice Cabanis1, Andreas Bechdolf3,Jutta Herrlich4, Stephanie Loos-Jankowiak5, Tilo Kircher1, Stephanie Kiszkenow6, Stefan Klingberg7,Mareike Kommescher3, Steffen Moritz8, Bernhard W. Mller5, Gudrun Sartory9, Georg Wiedemann10, Andreas Wittorf7,Wolfgang Wlwer6, and Michael Wagner2

1Department of Psychiatry and Psychotherapy, Philipps-University, Marburg, Germany; 2Department of Psychiatry and Psychotherapy,Rhineland Friedrich Wilhelms University, Bonn, Germany; 3Department of Psychiatry and Psychotherapy, University of Cologne,Nordrhein-Westfalen, Germany; 4Department of Psychiatry, Psychosomatics and Psychotherapy, University of Frankfurt, Hessen,Germany; 5Clinic for Psychiatry and Psychotherapy, University of Duisburg- Essen, Nordrhein-Westfalen, Germany; 6Department ofPsychiatry and Psychotherapy, University of Dsseldorf, LVR-Clinic Dsseldorf, Nordrhein-Westfalen, Germany; 7Department ofPsychiatry and Psychotherapy, University of Tbingen, Baden-Wuertenberg, Germany; 8Department of Psychiatry and Psychotherapy,

University of Hamburg, Hamburg, Germany;9

Department of Psychology, University of Wuppertal, Nordrhein-Westfalen, Germany;10Hospital of Psychiatry and Psychotherapy, Fulda, Germany

*To whom correspondence should be addressed; Department of Psychiatry and Psychotherapy, Philipps-University of Marburg,Rudolf-Bultmann-Street 8, D-35039 Marburg, Germany; tel: +49-6421-58-65359, fax: +49-6421-58-67099, e-mail:[email protected]

Theoretical models postulate an important role of attri-butional style (AS) in the formation and maintenanceof persecutory delusions and other positive symptoms ofschizophrenia. However, current research has gathered con-

flicting findings. In a cross-sectional design, patients withpersistent positive symptoms of schizophrenia (n = 258)and healthy controls (n= 51) completed a revised versionof the Internal, Personal and Situational AttributionsQuestionnaire (IPSAQ-R) and assessments of psychopa-thology. In comparison to controls, neither patients with

schizophrenia in general nor patients with persecutory delu-sions (n= 142) in particular presented an externalizing andpersonalizing AS. Rather, both groups showed a self-blam-ing AS and attributed negative events more toward them-selves. Persecutory delusions were independently predictedby a personalizing biasfor negative events (beta = 0.197,P= .001) and by depression (beta = 0.152, P= .013), but

only 5% of the variance in persecutory delusions could be

explained. Cluster analysis of IPSAQ-R scores identifieda personalizing (n= 70) and a self-blaming subgroup(n = 188), with the former showing slightly more pro-nounced persecutory delusions (P= .021). Resultsindicatethat patients with schizophrenia and patients with persecu-tory delusions both mostly blamed themselves for negative

events. Nevertheless, still a subgroup of patients could beidentified who presented a more pronounced personalizingbiasand more severe persecutory delusions. Thus, AS inpatients with schizophrenia might be less stable but more

determined by individual and situational characteristics

that need further elucidation.

Key words: schizophrenia/persecutory delusions/positive symptoms/attributional style/depression/negative emotions

Attributional style (AS) is defined as the way of infer-ring a causal explanation for important life events,1,2either toward oneself (internal), toward other persons(personal), or toward circumstances or fate (situational).For example, if a friend starts a fight with me, it is pos-sible to attribute this event to internal factors (I am abad person), to personal factors (He is annoyed quitequickly), or to situational factors (We lived in differentparts of the country).

Analysis of AS in schizophrenia derived from the clini-

cal insight that persecutory delusions can be viewed asan excessive tendency to attribute negative events towardother persons. Initial studies used the Attributional StyleQuestionnaire (ASQ),3 an instrument originally devel-oped for the assessment of AS in depression. These stud-ies found that patients with persecutory delusions showedmore internal attributions for positive events and lessinternal attributions for negative events, compared withcontrols. This AS has been termed self-serving bias orexternalizing bias (EB).46Because the ASQ showed quite
mailto:[email protected]?subject=mailto:[email protected]?subject=


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low reliability indices (Cronbachs alpha between .39 and.52)7and cannot differentiate between external attributionstoward other persons (personal attributions) and towardcircumstances (situational attributions), Kinderman andBentall7developed the Internal, Personal and SituationalAttributions Questionnaire (IPSAQ) and found thatpatients with persecutory delusions blamed other persons

more often than circumstances for negative events, whichsupports thepersonalizing bias (PB)hypothesis.8,9

Due to these findings, EBand PBwere incorporatedinto theoretical models as cognitive biases triggeringthe development and maintenance of persecutory delu-sions1012and positive symptoms in schizophrenia.1315

However, recent research has questioned these assump-tions because several studies that used the IPSAQ andcompared patients with persecutory delusions and con-trols did not find the hypothesized EB and PB1621 oreven found a less pronounced EB.11 Studies that com-pared patients with schizophrenia and controls found a

more pronounced EB but an equivalent level of PB inpatients5,22 or no differences between patients and con-trols.23 Even in a recent meta-analysis, neither a pro-nounced EBnor a pronounced PBcould be identified inpatients with schizophrenia (n = 212) in comparison tocontrols.24

These inconsistent results could be explained by anumber of factors: First, previous studies in patients withpersecutory delusions were mostly of small sample size(between 14 and 40 patients:),6,9which may have obscuredor even exaggerated results with a medium or minor effectsize.25The problem of small sample sizes is aggravated by

patients heterogenity with regard to psychopathology.Consequently, a large-scale study is necessary in order toaddress the question of whether EBand PBare associ-ated with persecutory delusions and schizophrenia.

Second, some inconsistent results could be explainedby specific features of the questionnaires used. Whilethe IPSAQ by Kinderman and Bentall9 introduced theimportant discrimination between personal and situ-ational external attributions, it is not without problemseither, with regard to its limited reliability (0.610.76)7,26and also with regard to its demand characteristics. TheIPSAQ forces a person to make a clear choice whetheran event is caused exclusively by internal, personal, or

situational factors even if a person (realistically) assumesthat an event is caused by multiple factors. Patients withschizophrenia might have particular problems in makingsuch a decision because they often tend to decide sponta-neously, without gathering a sufficient amount of infor-mation (jumping to conclusions bias).27,28Thus, the use ofthe original IPSAQ might lead to a distorted view of ASin patients with schizophrenia, and possibly to inconsis-tent findings as well.

Rather than enforcing respondents to choose between3 attributional alternatives by method, it is interest-ing to study whether patients with schizophrenia and

persecutory delusions indeed present a more mono-causal AS in comparison to controls who might pres-ent a more balanced and multifactorial view. Finally,in light of patients heterogeneity with regard to psycho-pathology, it is interesting to assess whether there are dis-tinct subgroups of patients who might differ with regardto their AS.

In order to derive clear-cut evidence about the pres-ence and clinical correlations of AS, we conducted a largemulticenter study with patients with positive symptomsof schizophrenia and controls, employing a revised ver-sion of the IPSAQ that allows the subject to rate therelative degree of the contribution of internal, personal,and situational factors toward important life events(IPSAQ-R).29,30 We hypothesize (1) that patients withpersistent positive symptoms and (2) especially patientswith persecutory delusions show a more pronounced EB,PB, and monocausality bias in comparison to controls.Furthermore, (3) we assumed that externalizing, person-

alizing, and monocausal AS are associated with delusionsof persecution and (4) that distinct subgroups of patientswho differ in their AS can be identified empirically.

Method

Participants

Participants were 258 patients with schizophrenia and 51healthy controls from the Cognitive behavioural therapyfor persistent positive symptoms (CBTp) in psychoticdisorders Trial31 (ISRCTN29242879), a multicenteredrandomized controlled trial investigating the efficacy of

CBTp for patients with schizophrenia in comparison tosupportive therapy. Patients were recruited from 6 differ-ent psychiatric settings; healthy controls were recruitedvia press releases and matched with regard to age, gender,and education to the first 51 patients that were alreadyrecruited.

From the study sample (n = 330), several patients (n =57) did not participate at this ancillary study: 9 patientsdropped out before they were asked to participate, 48patients refused to be tested for the ancillary study. Fromthe remaining sample (n = 273), several patients (n =15) were excluded because they did not understand theinstructions of the IPSAQ-R: They presented no causal

explanation for more than 3 items (n = 12), they stated Idont know as a causal explanation for more than 3 situ-ations (n = 2), or they wrote down the same causal expla-nation for more than 3 situations (n = 1). There were nostatistically significant differences between patients whorefused to be tested and those who endorsed testing withregard to sociodemographic and clinical variables (allP> .10).

Patients were diagnosed with a schizophrenia spectrumdisorder (schizophrenia [n= 201], schizophreniform dis-order [n= 5], schizoaffective disorder [n= 33], delusionaldisorder [n= 17]) as assessed with the Structured Clinical


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Interview for DSM-IV32 according to DSM-IV-TR.33Further inclusion criteria were persistent positive symp-toms for at least the last 3 months and a minimum scoreof 4 in the item P1 (delusions in general: n= 219) or inthe item P3 (hallucinations: n= 39) of the Positive andNegative Syndrome scale (PANSS),34age between 18 and59, adequate language fluency and a verbal intelligence

quotient (IQ) > 80 in the German vocabulary IQ testMWT-B.35 In line with other studies,9,17,18exclusion cri-teria for controls were mental disorders in their lifetime.Most of the patients (n = 142, 64.8%) presented delu-sions of persecution (defined as a minimum score of 4in the PANSS item P6). All participants were informedabout the assessment and gave written informed consent.The ethics committees at the 6 centers medical facultiesapproved the study.

Measures

The IPSAQ-R29,30consists of 16 items describing 8 posi-tive and 8 negative situations. For each item, subjectsare asked to put themselves in the position of someoneexperiencing the particular situation and to infer andwrite down the most probable causal explanation forit. They are then asked to estimate in percent whethertheir causal explanation is due to internal, personal, orsituational factors. For example, if a person interpretsthe item A friend says that he does not respect you inthe sense of I am a bad person, an estimation of thecausal explanation as 80% internal, 20% personal, and20% situational would be consistent. If the percentage

estimations do not add up to 100%, they are rescaled sothat their sum equals 100%. First, for every item, the sumof percentage estimations for internal, personal, andsituational attributions is computed (eg, 40% internal +50% personal + 70% situational = 180%). In the nextstep, the rescaled percentage estimations are computedas follows: rescaled percentage estimation = (formerpercentage estimation 100)/former sum of percentageestimations (eg, rescaled percentage estimation = (40 100)/180 = 22.22%).

Six attributional scores are calculated by adding upthe rescaled percent ratings of internal, personal, andsituational attributions for positive and negative events.

Moreover, several biases are computed according to pre-vious studies.7EBonly regards internal attributions andis present when a person attributes more positive thannegative events toward internal causes, hence to himself/herself. It is computed by subtracting the internal nega-tive score from the internal positive score. The PBonlyregards negative events and is present when a personattributes negative events rather to personal than to situ-ational factors. It is calculated by dividing the personalnegative score by the sum of personal negative scoreand situational negative score. Moreover, in accordanceto Moritz et al,30 a monocausality biaswas present if a

person at least in 1 situation estimates that an event iscaused by 1 attributional factor by a minimum score of80%. It was computed by counting the items that wererated in this way. Range of Cronbachs alpha for attribu-tional scores indicated sufficient to good internal consis-tency (between .71 and .81 [mean = .79] in patients andbetween .75 and .83 [mean = .79] in controls).

The PANSS34 is a semistructured interview assessing30 symptoms divided into 3 standard scales (positivesymptoms, negative symptoms, general psychopathol-ogy) using a 7-point Likert scale. PANSS rating was per-formed by trained raters, interrater reliability (correlationR2) was satisfactory to high (.92 for the PANSS positivescale and .86 for the PANSS negative scale).31

The Calgary Depression Rating Scale for Schizophrenia(CDSS)36 was used in order to assess observer-rateddepressive symptoms.

AnalysisFirst, we used Fishers exact tests, Chi-square tests, ttests, and ANOVAs in order to compare patients withschizophrenia and controls and patients with persecutorydelusions (PD), patients without persecutory delusions(Non-PD), and controls in sociodemographic and clini-cal variables. In case of group differences in specific vari-ables, it was analyzed whether these variables are relatedto AS, using Pearsons 2-tailed correlations. If these vari-ables were related to AS, they were included as covariatesin all statistical analyses.

All IPSAQ-R scores were normally distributed within

all groups with the exception of EBand monocausalitybias, and inspection of the data revealed no outliers. Inorder to investigate differences in AS and attributionalbiases between patients with schizophrenia and controls(Hypothesis 1), ANOVAs were performed using attribu-tional scores and biases as dependent variables if Levenetests indicated homogeneous variances, even if vari-ables were not normally distributed, because parametrictests show higher statistical power compared with non-parametric tests.37,38 In case of heterogeneous variances(monocausality bias), nonparametric tests were used(Mann-Whitney U test, Kruskal-Wallis test). We con-trolled these tests for important covariates by performing

a linear regression analysis using the covariate as pre-dictor and monocausality biasas criterion and saved thestandardized residuum scores. These scores were includedas dependent variables in nonparametric tests. In order toprevent alpha inflation, Bonferroni corrections were per-formed for each event type (eg, for positive events: P=.05/3 attributional loci = 0.017). The same procedure wasused in order to assess differences between patients withpersecutory delusions and controls in attribution biases(Hypothesis 2).

In order to investigate whether attribution biases areassociated with delusions of persecution (Hypothesis 3),


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we first examined bivariate relations between sociode-mographic variables, delusions of persecution (PANSSitem P6), and attribution biases using Pearsons 2-tailedcorrelations. Second, all variables that showed a statisti-cally significant association with persecutory delusionswere included into the multivariate regression analysis(ENTER method) predictors and persecutory delu-

sions were included as criterion. Multivariate regressionanalysis was controlled for multicollinearity by investi-gating the variance inflation factors and tolerance sta-tistics. Finally, we analyzed whether there are distinctsubgroups of patients with a comparable AS who couldbe identified empirically by a hierarchical cluster analysis(Hypothesis 4). The Wards method was used, and the 6IPSAQ-R scores in the patient sample were included ascluster variables and squared Euclidian distance as dis-tance measure.

Results

Table 1 shows sociodemographic and clinical data ofpatients with schizophrenia, patients with persecutorydelusions (PD), patients without persecutory delusions(Non-PD), and healthy controls. There were no statisti-cally significant differences between patients with schizo-phrenia and controls and between PD, Non-PD, andcontrols in terms of age, gender, or education. Comparedwith controls, patients with schizophrenia showed sig-nificantly lower verbal intelligence scores (MWT-B).Moreover, both PD and Non-PD showed a lower verbalintelligence score in comparison to controls. In compari-

son to Non-PD, PD presented a more pronounced level ofpositive symptoms and depressive symptoms, while bothgroups were comparable in terms of negative symptoms.

As only the monocausality bias was related to verbalintelligence (patient group: r= .215, P = .004; controls:r= .338, P = .018), all group comparisons in monocau-sality biaswere controlled for verbal intelligence.

Group Comparisons in AS

Results of comparisons between patients and controls inAS are depicted in table 2. Because most Levene tests indi-cated homogeneous variances (all P > .05), groups were

compared in their AS with ANOVAs. With regard to mono-causality bias, we used a Mann-Whitney U tests becausethe Levene test indicated heterogeneous variances. In com-parison to controls, patients with schizophrenia presentedmore internal attributions and less personal attributionsfor negative events and a reduced EB. With regard to otherattributional scores, there were no statistically significantdifferences between the 2 groups. The observed effect sizes(partial eta)2indicated large effects.

In the next step, patients with persecutory delusions(PD: n = 142) were compared with controls. Again,because all Levene tests (with the exception of the

monocausality bias) indicated homogeneous variances(all P > .05), groups were compared in their AS withANOVAs. With regard to monocausality bias, we usedMann-Whitney Utests because the Levene test indicatedheterogeneous variances. As depicted in table 3, resultswere largely comparable to those in the full sample; incomparison to controls, patients showed fewer personal

attributions for negative events and a reduced EB. Theobserved effect sizes indicated large effects. With regardto other attributional scores, there were no statisticallysignificant differences between the 2 groups.

Associations Between AS and Delusions of Persecution

First, bivariate correlation analysis revealed that perse-cutory delusions were associated with a pronounced PB(r = .164, P = .008) and with more severe depression(CDSS sum: r= .130, P = .037). Sociodemographic andother clinical variables were not related to persecutory

delusions. In the next step, we performed a multivariateregression analysis using PB and depression as predic-tors and persecutory delusions as criterion variable. Themodel was statistically significant [F(2,254) = 8.013, P .001, adjusted R2= .052)], and both depression (= .152;P = .013) and PB (=.197; P = .001) were significantpredictors, the amount of explained variance in delusionsof persecution indicated a small effect size. Including theinteraction between PBand depression as predictor didnot explain a significant amount of variance (P > .10), incomparison to the first model.

Cluster Analyses

Finally, a hierarchical cluster analysis was performed.Inspection of squared Euclidian distance led to a plau-sible 2-cluster solution (Cluster 1: 188 patients, Cluster2: 70 patients). As depicted in table 4, patients in the firstcluster presented a less pronounced PB, compared withcontrols. In comparison to controls and patients in thefirst cluster, patients in the second cluster presented amore pronounced PB.

In the next step, clusters were compared with regardto sociodemographic and clinical variables using t tests(2-tailed). There was only 1 statistically significant differ-ence between the 2 clusters: Patients in the second clus-ter showed more pronounced delusions of persecution[PANSS P6: Cluster 1: mean = 3.40 (SD = 1.48), Cluster2: mean = 3.87 (SD = 1.31); F(1,256) = 5.462, P = .02,partial eta2 =.021); group differences were of mediumeffect size.

Discussion

In comparison to controls, patients with schizophreniaand patients with persecutory delusions showed a self-blaming AS and attributed negative events more towardthemselves in comparison to positive events. Nevertheless,


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S. Mehl et al

Ta

ble1

.Means,StandardDdeviations,andComparisonsofPatientsWithSschizophreniaandControlsRegardingSociodemographicandClinicalVariables

PatientsWith

Schizophrenia

(n=258);n(%

)/M

(SD)

HealthyControls

(HC)(n=51);n

(%)/M(SD)

TestStatistics

PatientsWith

PersecutoryDelusions

(PD)(n=142);n

(%)/M(SD)

PatientsWithout

PersecutoryDelusions

(Non-PD)(n=116);n

(%)/M(SD)

TestStatistics

Gender(female)

107(41.5%)

21(41.2%)

P=.969a

58(40.85%)

49(42.24%)

X2(2)=.158,P=.924

Educationgrade

completedb

13y:135,10y:74,

9y:48,none:3

13y:26,10

y:23,9y:2

2(5)=10

.223,P=.069

High:75,medium:

40,

low:30,none:2

High:61,medium:35,

low:182

2(10)=16.119,P=.096

Age(y)

37.44(9.54)

35.77(9.47)

F(1,307)=

0.152,P=.284

37.75(9.6)

37.32(9.62)

F(2,306)=0.742,P=.477

VerbalIQ

107.29(14.88)

114.88(15.38)

F(1,307)=

11.053,P.001

105.98(15.57)

107.13(14.49)

F(2,306)=5.511,P=.004;

PD,

Non-PD C1, HC, HC > C1

Situational positive scoreb,c 21.85 (11.56) 9.32 (6.20) 14.64 (9.86) Chi2= 75.469, P .001, C1> C2,HC, HC > C1Internal negative scorec,d 46.59 (16.59) 40.87 (14.19) 36.43 (11.46) Chi2= 10.100, P= .006, C1 > HCPersonal negative scorec,d 29.02 (11.15) 49.19 (12.47) 43.68 (15.63) Chi2= 118.981, P .001, C2 > C1, HC, HC > C1Situational negative scorec,d 24.09 (12.68) 9.94 (6.49) 19.89 (13.17) Chi2= 73.769, P .001, C1 > C2, HC > C2Externalizing biasa 8.11 (17.32) 8.74 (18.50) 18.07 (15.77) F(2,306) = 4.147, P= .017, partial eta2= .027, C1 < HCPersonalizing biasc .57 (.17) .84 (09) .69 (.18) Chi2= 118.396, P .001, C2 > C1, HC, HC > C1Monocausality biasd,e 1.78 (2.97) 4.94 (4.40) 1.52 (2.27) Chi2= 3.993, P= .136

aANOVA.bBonferroni corrections for all positive events: P = .05/3 = .17.cKruskal-Wallis test.dANOVA with Bonferroni corrections for all negative events: P = .05/3 = .17.e

Kruskal-Wallis test using residual scores of monocausality bias(controlled for the influence of verbal intelligence [MWT-B]).

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Patients: Positive

Events

Controls:

Positive Events

Patients:

Negative Events

Controls:

Negative Events

Situational attributions

Personal attributions

Internal attributions

Fig. 1. Proportional attributions of causes for positive and negative events in patients with schizophrenia and controls.


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other persons are often responsible for negative events intheir life and feel depressed as a consequence. Given theless supportive social network of patients with schizo-phrenia,46this assumption might be plausible.

If our hypothesis of 2 different attribution processes , amore intuitiveand a more rationalprocess, is correct, ASshould not be viewed as a stable trait but as depending on

individual and situational characteristics that might acti-vate either a more intuitiveor a more rationalattributionprocess. This assumption fits well with the finding of anincreased PBin patients with schizophrenia after induc-tion of social stress. In order to test our hypothesis fur-ther, experimental studies are highly necessary in order toelucidate individual and situational conditions that mightactivate different attribution processes (eg, negative emo-tions, interpersonal threat).

At present, theoretical models of CBTp assume animportant role of AS in the formation and maintenanceof persecutory delusions15 and positive symptoms of

schizophrenia.13,14In light of our results, it might not bean exaggerated AS that enhances patients personal risk,but a more pronounced individual susceptibility towardsituational characteristics that activate a more intuitiveattribution process. With regard to CBTp, our studybrings forward the positive message that patients withschizophrenia are able to adapt their attributions to thepresent situation. Thus, they might be able to learn strat-egies in order to activate more rational attribution pro-cesses in difficult social situations as well.

In interpreting the findings of our study, some limitationsshould be considered. The IPSAQ-R is a new assessment

that has not been investigated with regard to its reliabilityand validity in a large sample of controls. Moreover, themode of assessment that forces persons to perform percent-age estimations could be criticized. But as discussed above,while not ideal, the IPSAQ-R presents several advantages incomparison to the classic IPSAQ: Patients are not requiredto decide between different attributional loci; thus, reliabil-ity indices are quite sufficient, and assessment of AS mightbe more accurate as it activates more rationalattributionprocesses. Furthermore, although our control group isquite small, we carefully checked for violation of assump-tions for statistical analyses. Investigation of monocausal-ity bias revealed no significant differences between patients

with schizophrenia and controls and between patients withpersecutory delusions and controls. However, it shouldbe noted that patients with schizophrenia presented amore pronounced monocausality bias, if intelligence wasnot controlled. Moreover, if a higher treshold (90%) wasused to assess monocausality, patients with schizophrenia(P= .015) and patients with persecutory delusions presenteda more monocausal attribution style in parametric tests(P = .003), if intelligence was not controlled. These resultssuggest that general intelligence helps to reach a balancedinterpretation of reality. Finally, although regressionanalysis seems to imply that PB is causal to delusions of

persecution or involved in their etiology, it must be notedthat all analyses are based on cross-sectional associations.Hence, it can be assumed that a PB could follow fromdelusions of persecution or merely be an attribute of themas well.

Several important conclusions can be drawn fromour results. In comparison to controls, patients with

schizophrenia in general and patients with persecutorydelusions in particular showed a self-blaming AS fornegative events. Nevertheless, a subgroup of patientscould be identified who presented a more pronouncedPBand more severe persecutory delusions as well. Thus,AS in patients with schizophrenia might be less stable butmore determined by individual and situational character-istics that need further elucidation.

Funding

German Federal Ministry of Education and Research

(BMBF: 01GV0618, 01GV0620).

Acknowledgments

We thank all members of the POSITIVE study: S. Baal,J. Berning, S. Beulen, G. Buchkremer, A. Bch, B. Conradt,Y. Eikenbusch, W. Gaebel, A. Gawronski, J. Gttgermans,A. Herold, U. Jakobi-Malterre, I.. Lengsfeld, W. Maier,K. Platt, B. Pohlmann, A. Rotarska-Jagiela, S. Sickinger,H. Smoltczyk, S. Unsld, A. Vogeley, A. Witt, andL. Zipp. The study was part of the BMBF researchprogram Research Networks on Psychotherapy. The

authors have declared that there are no conflicts ofinterest in relation to the subject of this study.

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