Resting-state alpha and gamma activity in affective disorder with ADHD symptoms: Comparison between bipolar disorder and major depressive disorder.

Although comorbid attention deficit/hyperactivity disorder (ADHD) symptoms are very common in mood disorder, its neurophysiological correlates have not been explored. This study aimed to examine clinical and neurophysiological correlates of ADHD symptoms in major depressive disorder (MDD) and bipolar disorder (BP). A total of 67 subjects with mood disorder, current depressive episode (38 subjects with MDD and 29 subjects with BP depression) were included in the analysis. Resting quantitative electroencephalography (qEEG) recordings were collected under eyes closed condition. ADHD symptoms, depression, anxiety, and lifetime hypomania were evaluated using self-report questionnaires. In MDD, ADHD symptoms did not show significant associations with anxiety and depression. In BP, ADHD symptoms showed significant associations with depression, anxiety and lifetime hypomania. Significant correlations with Adult ADHD self-report scales (ASRS) inattention score and total score were detected in left and right frontal alpha powers in MDD while significant correlation with ASRS hyperactivity score and ASRS total score were detected in right frontal gamma power in BP. Linear regression analyses revealed that left and right frontal alpha powers, depression and lifetime hypomania showed significant association with ASRS inattention score and ASRS total score in MDD. In BP, linear regression analysis showed ASRS hyperactivity score was associated with lifetime hypomania and the right frontal gamma power. MDD and BP showed different correlation patterns between frontal qEEG measures and ADHD symptoms. This might be associated with distinct neurobiological underpinnings of co-occurring ADHD symptoms in MDD and BP.