Beyond Attention-Deficit Hyperactivity Disorder: Exploring Psychiatric Comorbidities and Their Neuropsychological Consequences in Adults

Objectives: This study aimed to identify the psychiatric comorbidity status of adult patients diagnosed with attention-deficit hyperactivity disorder (ADHD) and determine the impact of comorbidities on neuropsychological outcomes in ADHD. Methods: The study participants were 124 adult patients with ADHD. Clinical psychiatric assessments were performed by two boardcertified psychiatrists in accordance with the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. All participants were assessed using the Mini-International Neuropsychiatric Interview Plus version 5.0.0 to evaluate comorbidities. After screening, neuropsychological outcomes were assessed using the Comprehensive Attention Test (CAT) and the Korean version of the Wechsler Adult Intelligence Scale, Fourth Edition (K-WAIS-IV). Results: Mood disorders (38.7%) were the most common comorbidity of ADHD, followed by anxiety (18.5%) and substance use disorders (13.7%). The ADHD with comorbidities group showed worse results on the Perceptual Organization Index and Working Memory Index sections of the K-WAIS than the ADHD-alone group (p=0.015 and p=0.024, respectively). In addition, the presence of comorbidities was associated with worse performance on simple visual commission errors in the CAT tests (p=0.024). Conclusion: These findings suggest that psychiatric comorbidities are associated with poor neuropsychological outcomes in adult patients with ADHD, highlighting the need to identify comorbidities in these patients.