IQ and socio-occupational functioning in relation to obsessive-compulsive symptoms severity in a clinical sample of adolescents.

Obsessive-compulsive disorder (OCD) is often comorbid with other psychiatric conditions, leading to severely impaired functioning and poor quality of life. Until now, the relationship between obsessive-compulsive symptoms (OCS) and functioning has been studied mainly through a categorical approach (i.e., presence/absence of the disorder), leaving more dimensional analyses almost unexplored. Therefore, the present study investigates the association between OCS and both intellectual functioning (IQ) and socio-occupational functioning across different levels of OCS severity. 341 help-seeking adolescents (65% female, mean age = 15.37 years, SD = 1.37) with different psychopathologies underwent an in-depth clinical examination using the Comprehensive Assessment of At Risk Mental States (CAARMS), through which OCS were also evaluated, and the Kiddie-Schedule for Affective Disorder and Schizophrenia - Present and Lifetime - DSM-5 (K-SADS-PL). Cognitive functioning was assessed using a full IQ test (WISC-IV or WAIS-IV), and socio-occupational functioning was assessed using the Social and Occupational Functioning Assessment Scale (SOFAS). A negative quadratic curvilinear (i.e. inverted U-shape) relationship was found between OCS severity and IQ (β=-1.11, p < .05), and a negative linear relationship was observed between OCS severity and socio-occupational functioning (β=-1.32, p < .01). While the association with IQ remained significant after controlling for sociodemographic variables and psychopathology symptoms (β=-0.471, p = .005), the association with socio-occupational functioning did not (β=-0.034, p = .487). These results indicate that OCS are differentially associated with IQ depending on their severity within the adolescent psychiatric population. In particular, mild OCS appear to be associated with a higher IQ relative to no OCS or severe OCS.