Annual Research Review: Does late‐onset attention‐deficit/hyperactivity disorder exist?

Abstract

Attention-deficit/hyperactivity disorder (ADHD) is conceptualized as an early onset childhood neurodevelopmental disorder. Prevalence in adults is around two-thirds that in childhood, yet longitudinal outcome studies of children with ADHD found a minority continue to meet full criteria in adulthood. This suggests that not all adult cases meet ADHD criteria as children, a conclusion supported by earlier studies relying on retrospective recall in adolescent and adult samples. More recently prospective follow-up of population and control samples suggest that adolescent and young adult ADHD is not always a continuation of childhood ADHD. Here, we review the literature on age of onset, to explore whether late-onset ADHD exists, and if so, examine the evidence for whether this should be considered the same or a different disorder as childhood onset ADHD. We conclude that current evidence supports the view that a significant proportion of young adults meeting criteria for ADHD would not have met full diagnostic criteria for ADHD as children. However, many in the late-onset group show some ADHD symptoms in childhood, or an externalizing disorder such as oppositional defiant disorder. Furthermore, the current studies suggest that most (but not all) cases of late-onset ADHD develop the disorder between the ages of 12-16 and can therefore be considered adolescent or early adult onset ADHD. There is a relative lack of data spanning young to older adulthood to address the question of adult-onset. Currently, there is insufficient data to clarify the extent to which early and late onset ADHD reflect a different balance of genetic and environmental risks or share the same underlying neural mechanisms. Clinicians should be aware that significantly impairing forms of ADHD can emerge beyond the age of 12 years, although perhaps rarely in the context of a complete absence of precursors. The current evidence on treatment responses is limited.

The importance of a developmental perspective in Psychiatry: what do recent genetic-epidemiological findings show?

“…Interestingly, several recent longitudinal studies adopted a developmental life-course perspective to assessing ADHD and identified an apparent "late-onset" form of ADHD where ADHD symptoms were not reported in childhood but emerged newly in adolescence or adult life [46]. These individuals would not meet current diagnostic criteria for ADHD if their age-at-onset was known and the discovery of this group challenges the conceptualization of ADHD as a neurodevelopmental disorder.…”

Commentary: ADHD lifetime trajectories and the relevance of the developmental perspective to Psychiatry: reflections on Asherson and Agnew‐Blais, (2019)

“…The first study to address this question showed, astonishingly, that 90% of the adults who were diagnosed with ADHD had no history of the disorder during childhood. Perhaps even more astonishingly, this finding was soon replicated in a series of studies reviewed by Asherson and Agnew‐Blais () that reported that anywhere from <1% to 10% of ADHD cases emerge in adolescence and adulthood.…”

“…The new evidence that ADHD can emerge later than childhood comes with several questions (Castellanos, ; Caye, Sibley, Swanson, & Rohde, ; Faraone & Biederman, ; Shaw & Polanczyk, ). The review by Asherson and Agnew‐Blais () is timely in providing a detailed description of the data on which the findings are based and a thoughtful discussion of whether late‐onset ADHD is likely to be a real phenomenon as opposed to a methodological artifact.…”

“…As discussed by Asherson and Agnew‐Blais (), a number of pieces of evidence have accumulated that call into question the special status of childhood‐onset ADHD and suggest the existence of an adult‐onset group. For example, initial clinical accounts failed to show clinically meaningful differences between individuals reporting an early versus a later onset of disorder.…”

“…With so many new and controversial data and hypotheses challenging conventional wisdom about ADHD, Asherson and Agnew‐Blais () brilliantly illuminate key methodological and conceptual concerns, recommend future directions for research, and provide a thoughtful discussion of the implications for treatment. Importantly, they suggest that clinicians should consider the presence of symptoms and impairment criteria (rather than strict diagnostic thresholds) as guides to whether adults need treatment, not forgetting to consider exacerbating factors such as drug abuse and other disorders.…”