While it was previously believed that attention-deficit/hyperactivity disorder (ADHD) solely affected children, subsequent research determined that an estimated 50% of people with the disorder continue to have impairing symptoms in adulthood, and another 15% continue to meet the full criteria for ADHD diagnosis. New findings published in JAMA Psychiatry indicate that for some people, the disorder may not emerge until young adulthood.
Researchers at King’s College London, the University of São Paulo Medical School, and Duke University conducted a prospective, developmental study to investigate the persistence of ADHD from childhood to adulthood in a general population cohort. They also explored risk factors, outcomes, and differences between groups of participants with varying ages of ADHD onset. The sample consisted of 2040 participants selected from a birth register of same-sex twins born in England and Wales who were members of the Environmental Risk (ERisk) Longitudinal Twin Study.
Participants were 5 years old at the time of the initial assessment, and had home-based follow-up sessions at ages 7, 10, 12, and 18 years. With the exception of the final session, which involved only the participant, assessments were conducted with participants and their mothers. Additionally, the children’s teachers completed questionnaires regarding participants at the various follow-up ages. At the age of 18, participants also identified people who knew them well and could provide additional data as co-informants.
To qualify for an ADHD diagnosis, participants had to have at least 6 of 18 symptoms of inattention and hyperactivity-impulsivity based on the DSM-IV and the Rutter Child Scales, and they had to meet diagnostic criteria at the age of 5, 7, 10, or 12.
Overall, the portions of the sample meeting ADHD criteria were as follows: 12.1% across childhood; 6.8% at 5 years of age; 5.4% at 7 years old; 3.4% at 10 years old; and 3.4% at age 12. At age 18 years, 8.1% of the sample met criteria for ADHD. At this age, in order to receive an ADHD diagnosis, participants had to endorse 5 or more inattentive and/or 5 or more hyperactivity-impulsivity symptoms per the DSM-5, and they also had to report at least moderate interference with their functioning pertaining to family, friends, school, and work.
Of the participants who met diagnostic criteria in childhood, 21.9% of them also met criteria at age 18. Among those who were diagnosed with adult ADHD, 67.5% did not meet criteria at any point in childhood. Persistent ADHD “was associated with more symptoms (odds ratio [OR], 1.11 [95% CI, 1.04-1.19]) and lower IQ (OR, 0.98 [95% CI, 0.95-1.00])” and, in adulthood, “with more functional impairment (school/work: OR, 3.30 [95% CI, 2.18-5.00], home/with friends: OR, 6.26 [95% CI, 3.07-12.76]), generalized anxiety disorder (OR, 5.19 [95% CI, 2.01-13.38]), conduct disorder (OR, 2.03 [95% CI, 1.03-3.99]), and marijuana dependence (OR, 2.88 [95% CI, 1.07-7.71]), compared with those whose ADHD remitted,” the authors reported. Participants with late-onset ADHD showed similar symptoms, impairment, and elevated rates of mental disorders as those with persistent ADHD.
Overall, these results are consistent with previous findings and “suggest that adult ADHD is more complex than a straightforward continuation of the childhood disorder,” the researchers concluded.
Agnew-Blais JC, Polanczyk GV, Danese A, Wertz J, Moffitt TE, Arseneault L. Evaluation of the Persistence, Remission, and Emergence of Attention-Deficit/Hyperactivity Disorder in Young Adulthood. JAMA Psychiatry. 2016; doi: 10.1001/jamapsychiatry.2016.0465.