Risks of bipolar disorder, depressive disorder, and traumatic brain injury among siblings of patients with attention-deficit hyperactivity disorder

Background: Previous studies have suggested that the unaffected siblings of patients with attention-deficit hyperactivity disorder (ADHD) experience deficits in attention, impulsivity control, and behavior inhibition, which are associated with health-risk behaviors. However, risks to mental and physical health among the unaffected siblings of ADHD probands have rarely been investigated. Methods: Using the Taiwan National Health Insurance Research Database, 5128 unaffected siblings of ADHD probands born between 1980 and 2000 were included in our study along with 20,512 age-and sex-matched controls, and they were followed from 1996 or birth until the end of 2011. Mental and physical health risks, including affective disorders, traumatic brain injury (TBI), and sexually transmitted infection were identified during the follow-up period. Results: Logistic regression analyses with adjustments for demographic data showed that the unaffected siblings were more likely to develop unipolar depression (odds ratio [OR]: 1.76, 95% confidence interval [CI]: 1.39-2.22), bipolar disorder (OR: 2.10, 95% CI: 1. 09-4.05), and TBI (OR: 1.24, 95% CI: 1.14-1.36) than were the control group. Discussion: The unaffected siblings of patients with ADHD were prone to developing unipolar depression, bipolar disorder, and TBI later in life.