Role of COMT in ADHD: a systematic meta-analysis.

Attention-deficit/hyperactivity disorder (ADHD) is a common and highly heritable childhood-onset psychiatric disorder with significant genetic contribution. Considerable evidence has implicated involvement of dopaminergic system and the prefrontal cortex (PFC) in the pathomechanism of ADHD. The catechol-O-methyltransferase (COMT) gene is of particular interest for ADHD as its crucial role in the degradation of dopamine in the PFC. We summarized the reported findings investigating associations between COMT gene and ADHD and performed a meta-analysis of previous studies to assess the overall magnitude and significance of the association.