Are parents with bipolar disorder at higher risk of having offspring with ADHD? A systematic review.

Background: The offspring of parents with bipolar disorder (BD) and with attention deficit hyperactivity disorder (ADHD) have a higher risk of having the same condition. Both disorders also share psychopathological symptoms; however, little is known about their genetic overlap. To examine whether the offspring of parents with BD have a greater chance of being affected by ADHD, we conducted a systematic review.

Methods: From inception to August 12, 2024, we searched the PubMed, SciELO, PsycInfo and Cochrane databases. We included studies if they investigated the association of parental bipolar disorder with offspring outcomes and made a proper investigation of disorders using validated instruments based on the Diagnostic Statistical Manual of Mental Disorders (DSM) or the International Classification of Diseases (ICD) criteria. Studies were excluded if: parents were under 18 years old or over 70; did not report original data; systematic reviews; in vitro studies; with an animal model; offspring older than 17 years of age or with any comorbid diagnosis with ADHD. To assess risk of bias, two authors independently used the Newcastle-Ottawa Scale quality assessment tool.

Results: 23 articles met the inclusion criteria. The majority of the studies reported that the offspring of parents with BD were at higher risk for ADHD. Particularly, in all case‒control studies, the risk of ADHD was higher in the case group than the control group.

Conclusion: The current studies are yet heterogeneous and literature did not uncover the biological correlation of these disorders regarding genetic, biochemical, neuroimaging and neuropsychological aspects.