The Clinical Characteristics of ADHD and Obsessive-Compulsive Disorder Comorbidity. 
To investigate the clinical implications of obsessive-compulsive disorder (OCD) and ADHD comorbidity in adults.  The OCD patients who had and had no diagnosis of adulthood ADHD were compared in terms of several demographic and clinical variables.  The mean number of obsessions and compulsions; hoarding, symmetry, and miscellaneous obsessions; ordering/arranging and hoarding compulsions; total, attentional, and motor subscale scores of Barratt Impulsivity Scale (BIS)-11 were more frequent among the patients with OCD-ADHD.  The mean age of onset was more likely to be earlier in ADHD-OCD group than in OCD group.  Impulsivity, symmetry obsessions, and hoarding compulsions strongly predicted the coexistence between ADHD and OCD.  OCD-ADHD comorbidity in adults seemed to be associated with an earlier onset of OCD, with the predominance of impulsivity, and with a different obsessive-compulsive symptom (OC) profile from OCD patients without a diagnosis of ADHD.