Comparison of neurocognitive performance in familial versus sporadic obsessive-compulsive disorder

Background: Obsessive-compulsive disorder (OCD) is a heterogeneous disorder. Previous studies have indicated that sporadic and familial OCD differ phenotypically with respect to age of onset, symptomatology and comorbidity profile. Here, we compare neurocognitive functions in familial (having an affected first degree relative) and sporadic forms of OCD. Methods: The sample consisted of 169 individuals in three groups, familial OCD (n = 54), sporadic OCD (n = 55) and healthy controls (n = 60). They were assessed using the Mini International Neuropsychiatric Interview (MINI), the Yale-Brown Obsessive Compulsive Scale (YBOCS), the Hamilton Anxiety Rating Scale (HAM-A), the Hamilton Depression Rating Scale (HAM-D) and the Family Interview for Genetic Studies (FIGS). The neuropsychological battery comprised tests of processing speed (Color Trails 1), cognitive flexibility (Color Trails 2), working memory (Auditory 1-back & 2-back), new learning and recall (Rey Auditory Verbal Learning Test), response inhibition (Stop-Signal Task) and theory of mind (Social Cognition Rating Scale for Indian Settings - SOCRATIS). Statistical comparisons between the three groups were done using Analysis of Covariance, adjusting for relevant co-variates. Results: Familial and sporadic OCD groups were comparable with respect to all sociodemographic and clinical characteristics except HAM-A (p < 0.001) & HAM-D scores (p < 0.001). After adjusting for age, gender, education, anxiety/depression scores and applying the Bonferroni-Holm correction for multiple comparisons, familial OCD were found to have poorer performance in Color Trails 2 (Cohen's f = 0.31) and N-back 2 tests (f = 0.38), in comparison to sporadic OCD. Conclusions: Our findings indicate that the familial OCD group may have greater neurocognitive impairments, particularly in the domains of cognitive flexibility and working memory. The current study adds further evidence to the characterization of familial OCD. This sub-typing warrants further study, and this may offer clues to deciphering genetic and neurobiological aspects in OCD.