Shared risk factors for intermittent explosive disorder, attention deficit hyperactivity disorder and conduct disorder: A systematic review

This review aims to analyse the associations between Intermittent Explosive Disorder (IED), Attention-Deficit Hyperactivity Disorder (ADHD), and Conduct Disorder (CD), particularly regarding the relative importance of shared risk factors in the development of these disorders. Studies were obtained from multiple databases, following the guidelines of Preferred Reporting Items for Systematic Review and Meta-Analysis. Of the 6715 documents obtained, 44 were retained for in-depth analysis. The study characteristics, study design, participants, objectives and main findings were extracted from each study. Overall, the results suggest that (1) the shared risk factors encompass a range of adverse childhood experiences, including childhood exposure to violence, poor quality early parenting, socioeconomically disadvantaged backgrounds, problematic behaviours within educational settings,and inflammation response (2) the risk factors for IED are more associated with environmental factors than genetic factors, although the importance of the latter is recognised and (3) compared to ADHD and CD, research studies on IED is relatively limited.