Predictors of persistence of ADHD into adulthood: a systematic review of the literature and meta-analysis

Attention-deficit/hyperactivity disorder (ADHD) is traditionally conceptualized as a neurodevelopmental disorder that continues into adulthood in up to half of diagnosed cases. In light of current evidence, factors associated with the course of the disorder remain unknown. We performed a systematic review of the literature searching for risk markers from childhood that predicted the persistence of ADHD into adulthood. We reviewed 26,168 abstracts and selected 72 for full-text review. We identified data from 16 studies, comprising 6 population-based retrospective samples and 10 clinical follow-ups. We performed meta-analyses of factors evaluated by at least three studies. Severity of ADHD (OR 2.33, 95 % CI = 1.6-3.39, p < 0.001), treatment for ADHD (OR 2.09, 95 % CI = 1.04-4.18, p = 0.037), comorbid conduct disorder (OR 1.85, 95 % CI = 1.06-3.24, p = 0.030), and comorbid major depressive disorder (OR 1.8, 95 % CI = 1.1-2.95, p = 0.019) emerged as predictors already presented in childhood for ADHD persistence into adulthood. Further, we suggest that cohort studies should be designed to clarify such an important question for research and clinical practice.