Comorbidity of ADHD and suicide attempts among adolescents and young adults with bipolar disorder: A nationwide longitudinal study

Background Suicide is among the leading causes of death among people with bipolar disorder and has gained substantial attention in the psychiatric and public health fields. However, the role of attention deficit hyperactivity disorder (ADHD) in suicide among adolescents and young adults with bipolar disorder remains unknown. Methods Using Taiwan's National Health Insurance Research Database, we identified 500 adolescents and young adults from 2002 to 2008 aged between 15 and 24 years with bipolar disorder and ADHD. The sample was matched according to age and sex with 1500 (1:3) patients with bipolar disorder only and observed until the end of 2011. The patients who attempted suicide during the follow-up period were identified. Results Adolescents and young adults with bipolar disorder and ADHD had a greater incidence of attempted suicide than did those with bipolar disorder only (3.0% vs. 1.1%, p=0.005). After adjustment for demographic factors and psychiatric comorbidities, a Cox regression analysis determined that ADHD was an independent risk factor for attempted suicide (hazard ratio: 2.38, 95% confidence interval: 1.13-5.00) later in life among adolescents and young adults with bipolar disorder. Discussion Adolescents and young adults with bipolar disorder and ADHD had an increased likelihood of attempted suicide compared with adolescents and young adults with bipolar disorder only. Further study is required to investigate the possible pathophysiology among ADHD, bipolar disorder, and attempted suicide, and to assess whether prompt intervention for ADHD may reduce the risk of attempted suicide.