Comorbidity of ADHD and adult bipolar disorder: A systematic review and meta -analysis

Attention-deficit / hyperactivity disorder (ADHD) and Bipolar Disorder (BD) are common mental disorders with a high degree of comorbidity. However, no systematic review with meta-analysis has aimed to quantify the degree of comorbidity between both disorders. To this end we performed a systematic search of the literature in October 2020. In a meta-analysis of 71 studies with 646,766 participants from 18 countries, it was found that about one in thirteen adults with ADHD was also diagnosed with BD (7.95 %; 95 % CI: 5.31?11.06), and nearly one in six adults with BD had ADHD (17.11 %; 95 % CI: 13.05?21.59 %). Substantial heterogeneity of comor-bidity rates was present, highlighting the importance of contextual factors: Heterogeneity could partially be explained by diagnostic system, sample size and geographical location. Age of BD onset occurred earlier in patients with comorbid ADHD (3.96 years; 95 % CI: 2.65?5.26, p < 0.001). Cultural and methodological dif-ferences deserve attention for evaluating diagnostic criteria and clinicians should be aware of the high comor-bidity rates to prevent misdiagnosis and provide optimal care for both disorders.

Automated summary

ADHD and BD have a high degree of comorbidity in adults, with substantial heterogeneity in comorbidity rates. Patients with comorbid ADHD tend to have an earlier onset of BD. Cultural, geographical, and methodological differences should be considered for evaluating diagnostic criteria to prevent misdiagnosis and provide optimal care for both disorders.