Theory of mind in obsessive compulsive disorder: Relation with neurocognitive functions, overvalued ideas, insight level, schizotypal personali̇ty traits and other clinical features

Objective: Intrusive nature of obsessive thoughts, attributional mistakes of people for their symptoms and deterioration in thinking process over self thoughts may indicate an impairment in theory of mind abilities of patients with OCD. However, there are few studies which investigate theory of mind in OCD. The aim of our study is to investigate theory of mind disorder in OCD, which may be related with variables like neurocognitive functions, overvalued ideas, schizotypal personality traits, insight and disease severity level, illness duration, age of onset and duration without treatment. Method: 34 patient who have been diagnosed as OCD according to DSM-IV and 30 healthy control have been included our study. Both are between 18-55 ages. All participants have been given Dokuz Eylül Theory of Mind Index (DEToMI), Reading the Mind in the Eyes Test (RMET), neuropsychologic test battery, and Schizotypal Personality Questionnaire (SPQ). Neuropsychologic test measurement has been administered to evaluate neurocognitive functions and general cognitive factor has been calculated. Yale Brown Obsession and Compulsion Scale (YBOC-S) has been used to determine disease severity. The Overvalued Ideas Scale (OVIS) and eleventh item of Y-BOCS have been evaluated to determine overvalued ideas and insight level. Findings: DETMS total score, RMET total score, first order false belief scores and second order false belief scores of participants with OCD have been found to be lower when compared with healthy controls. Theory of mind test scores have been found to be correlated with neuropsychologic test results, which vary among weak and very strong correlation level. When, General cognitive factor and duration of education are controlled, only total score of DEToMI difference remains statistically significant. Patients have also a weak association between first order false belief test, total score of DEToMI and eleventh item of YBOC-S. No significant correlation between theory of mind tests and insigiht level remains statistically significant, when general cognitive factor is controlled. Total score of DEToMI, first order false belief test, metaphor comprehension and RMET test results have been found to be correlated with schizotypal personality traits in weak-moderate level. There is also a weak correlation between total scores of YBOC-S and DEToMI. First order false belief test and second order false belief test results are also moderately correlated with total score of YBOC-S. When general cognitive factor is controlled, both first order false belief test and second order false belief test remain statistically significant in terms of disease severity. Early-onset ( < 19 ages) OCD subgroup has a deterioration in RMET performance when compared with late-onset subgroup of the study, which remains statistically significant, when general cognitive factor is adjusted. Result: In our study, participants with OCD are found to have impairments in theory of mind abilities. Theory of mind functions of these patients are correlated with neurocognitive functions, schizotypal personality traits, disease severity and age of onset. Despite the relation between theory of mind ability and neurocognitive functions, providing that theory of mind is considered as a separate entity, it might help to elucidate etiopathogenesis of OCD.