The Impact of Childhood Attention Hyperactivity Disorder on Cognitive Function in Adult Obsessive-Compulsive Disorder Patients: A Comprehensive Study

Studies evaluating cognitive functions in patients with obsessive-compulsive disorder (OCD) have yielded inconsistent results in various cognitive domains. One key reason for contradictory findings is the frequent occurrence of comorbid psychiatric disorders in OCD. Attention deficit hyperactivity disorder (ADHD), especially in childhood, is one of the most common comorbidities in OCD. The aim of the current study was to identify potential differences in cognitive functions caused by childhood ADHD in adult OCD patients while minimizing the effects of symptoms that frequently accompany OCD, such as anxiety, depression, and age. The study included 35 OCD patients with childhood ADHD (OCD + cADHD), 44 OCD patients without childhood ADHD (OCD–cADHD), and 40 healthy controls (HC). Hamilton Depression and Anxiety Scales were applied to all participants. Next, the Cambridge Neuropsychological Test Automated Battery (CANTAB) [Paired-Associate-Learning (PAL), Cambridge Gambling Task (CGT), Stop Signal Test (SST), and Intra-/Extra–Dimensional Set-Shifting Test (IED)] was administered. The OCD patients without childhood ADHD (OCD − cADHD) exhibited higher mean scores in CGT-Risk-Taking and Bet Ratio compared to the HC. However, OCD patients with childhood ADHD (OCD + cADHD) also showed higher mean scores in CGT-Bet Ratio compared to the HC. The mean number of IED-Total Errors and IED-Total Trials was higher in the OCD + cADHD group compared to the HC. The OCD + cADHD group had a higher mean number of SST-Direction Errors and Missed Trials than other groups. The results of the current study suggest that even when potential confounding factors such as depression and anxiety are neutralized, the presence of childhood ADHD in adult patients with OCD led to differences in cognitive domains related to decision-making, flexible thinking, and impulsivity.