Adult-Onset Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is traditionally considered a childhood disorder. Recent inquiries have arisen regarding the concept of an “adult-onset” ADHD, wherein symptoms not observed in childhood manifest later in adulthood. Therefore, this chapter is a narrative review discussing adult-onset ADHD, including potential explanations for symptoms emerging in adulthood. ADHD criteria in adulthood may have some limitations based on the neurodevelopmental characteristics of ADHD and the decreases in certain symptoms (e.g., hyperactivity) with age in neurotypical adults. Some studies have found apparent longitudinal evidence of an adult-onset pattern of ADHD, whereby certain adults without symptoms of ADHD in childhood meet criteria in adulthood. Several counterarguments have been offered such as changes in reporting source (e.g., parent to adult), subthreshold symptoms increasing in adulthood, and missed symptoms in adolescence. Thus, more longitudinal studies are needed in order to evaluate whether new threshold guidelines (e.g., onset prior to 12 years old) impact the diagnosis of ADHD in adulthood. With the proliferation of social media platforms like TikTok, adults increasingly seek information about ADHD signs; however, concerns have arisen regarding the reliability of such information, potentially being associated with an overdiagnosis problem. Adult ADHD diagnosis demands thorough consideration of potential mimicking conditions like anxiety, depression, bipolar disorder, substance use disorders, sleep disorders, thyroid disorders, and neurological conditions, to ensure accurate diagnosis and tailored interventions. Moving forward, mental health practitioners should prioritize transparency and thoroughness in diagnosis, while policymakers must prioritize empirically supported decision-making. Laypersons interested in adult-onset ADHD should approach social media content cautiously and prioritize thorough evaluations with qualified mental health professionals.