Temperament in Schizophrenia and Bipolar disorders – A Meta-Analysis Jouko Miettunen Department of Psychiatry, University of Oulu, Finland

Cloninger’s temperament dimensions novelty seeking tendency to respond with intense excitement to novel stimuli and thereby initiating behavior harm avoidance tendency to respond intensively to signals of aversive stimuli, thereby stopping behavior reward dependence tendency to respond intensely to signals of reward, especially social rewards, thereby continuing particular behaviors persistence tendency to persevere in behaviors that have been associated with reward potential intermediate phenotypes in different psychiatric disorders Cloninger et al. Arch Gen Psychiatry 1993;50:975–90.

Meta-analysis Original studies have not compared temperament between patients with schizophrenia and bipolar disorders Systematic search of articles using several literature databases Miettunen et al. Pers Ind Diff 2006;41:1515–26; Compr Psychiatry 2007;48:161–9; Psychiatry Res 2008;160:106–14 Studies comparing cases (schizophrenia or bipolar disorder) and controls We found 13 studies on schizophrenia and 9 studies on bipolar disorder

Schizophrenia (13 studies) CountryCases/ Controls Bipolar disorder (9 studies) CountryCases/ Controls Aschauer et al. 1994Austria59/59Blairy et al. 2000Luxembourg50/89 Aukst Margetic et al. 2010Croatia120/120Engström et al. 2004Sweden100/100 Boeker et al. 2006Germany22/22Loftus et al. 2008USA85/85 Cortés et al. 2009Spain29/186Lövdahl et al. 2010Norway21/21 Gonzalez-Torres et al. 2009Spain61/64Nery et al. 2008USA73/63 Guillem et al. 2002Canada52/25Novakowska et al. 2005USA49/47 Gulec 2009Turkey50/50Osher et al. 1999Israel25/25 Hori et al. 2008Japan86/115Sayin et al. 2007Turkey90/90 Kurs et al. 2005Israel47/56Young et al. 1995Canada45/100 Poustka et al. 2010Finland38/4723 Ritsner & Susser 2004Israel90/136 Smith et al. 2008USA35/63 Szoke et al. 2002France45/126 TOTAL734/5747TOTAL528/620

P=0.061 P=0.048 P=0.037 P=0.147 Effect sizes (Cohen’s d): small, medium, and >0.8 large effect Comparisons between cases and controls in bipolar disorders and schizophrenia

Discussion The first study to pool case-control studies on schizophrenia and bipolar disorders in temperament low harm avoidance in bipolar disorders also when compared to other psychiatric disorders than schizophrenia (e.g. unipolar depression) low reward dependence in schizophrenia also when compared to other psychiatric disorders than bipolar disorders low sociability (negative symptom)

Discussion Previous studies have not found differences between psychotic and non-psychotic bipolar disorders Engström et al. J Affect Disord 2004;82:131–4 Overall novelty seeking was low in schizophrenia, high novelty seeking would correlate with substance use Van Ammers et al. J Nerv Ment Dis 1997;185:283–8 and hallucinations and delusions Guillem et al. Schizophr Res 2002;56:137–47

Future research Suggestive endophenotypes Effect of phase of illness infrequent and missing answers prodromal phase Clinical relevance treatment adherence substance use social and clinical outcome