Growing up with ADHD: findings from an 18-year longitudinal follow-up study of adults with childhood ADHD, their siblings, and controls

Background. Attention-deficit/hyperactivity disorder (ADHD) is a prevalent childhood-onset disorder (5-7%) and poses risks for adult functioning. Adult outcomes of childhood ADHD should be identified with long-term prospective follow-up studies investigating a broad range of outcomes. Method. Differences in outcomes (i.e., measures of psychiatric status, behavioral and emotional problems, academic and professional functioning, adaptive functioning, neurocognition, physical health, healthcare service use) were investigated in an 18-year follow-up study of adults with childhood ADHD (n=154, Mage=27.38, SDage=3.70, 68% males), their siblings without childhood ADHD (n=138, Mage=29.59, SDage=4.43, 35% males), and controls (n=129, Mage=28.17, SDage=3.53, 40% males). Post-hoc tests investigated whether observed differences between the ADHD group and controls may be driven by a current ADHD diagnosis, by comparing persistent ADHD, remitted ADHD, and control groups. Results. Childhood ADHD was related to worse functioning in adulthood on more than 60% of outcomes across all domains with these differences translating into small to large-sized effects (e.g., moderate/large differences in increased rates of ADHD and depression, externalizing problems, autistic traits, and worse neurocognitive outcomes). The siblings showed comparable functioning to controls. Persistent ADHD showed worse functioning on specific outcomes in the psychiatric, behavioral/emotional, adaptive, and physical health domains, as compared to remitted ADHD. Both ADHD groups had worse functioning compared to controls. Conclusions. Childhood ADHD increased the risk for worse functioning in adulthood, which was not driven by current ADHD status. No specific risks were identified for siblings of the childhood ADHD group in outcomes. The current study stresses childhood ADHD as a risk condition for long-term worse functioning.