BackgroundHigh rates of history of childhood attention deficit hyperactivity disorder (ADHD) symptoms have been found in obsessive-compulsive disorder (OCD) adults. Both, when comorbid, cause the clinical course to be unfavorable, more susceptibility to substance use, and a bad response to treatment. We planned to assess the impact of childhood ADHD symptoms on OCD adults and the effect of this on clinical characteristics and comorbidities of the disorder.ResultsOur cross-sectional investigation uncovered that 44% of the OCD patients had childhood ADHD symptoms. Patients with childhood ADHD manifestations with at present grown-up ADHD had more elevated amounts of depression, anxiety, and impulsiveness. OCD patients with child ADHD symptoms but not continued symptoms till adulthood versus those without child ADHD symptoms had higher levels of depression, anxiety, and impulsiveness and more severe OCD symptoms.ConclusionADHD in adults with OCD is associated with some features impairing the clinical picture including higher levels of anxiety, depression, and impulsiveness reflecting more chronic illness. A childhood history of ADHD symptoms, even if not continued till adulthood, caused more impulsiveness, more severe OCD symptoms, and more anxiety and depression comorbidity.