An 18-year follow-up study revealed that psychiatric research Evidence shows that children diagnosed with attention-deficit/hyperactivity disorder tend to face a wider range of challenges in different areas of their lives in adulthood than other children. This study evaluated adults diagnosed with ADHD in childhood, along with siblings without ADHD and an unrelated control group. The findings show that siblings of children with ADHD generally experience typical adult functioning, suggesting that many of the long-term difficulties are specific to the condition itself rather than family co-education.
Attention-deficit/hyperactivity disorder, commonly known as ADHD, is a neurodevelopmental condition characterized by a persistent pattern of inattention, hyperactivity, and impulsivity. It affects approximately 5% to 7% of children worldwide. While it was once thought that the condition was outgrown, scientists now recognize that the condition often persists into adulthood.
Longitudinal studies follow the same individuals over long periods of time, allowing scientists to observe how childhood health changes over time. Previous research suggests that adults diagnosed with ADHD in childhood may have higher rates of mood disorders, lower educational attainment, and less job security. However, much of the existing research focuses primarily on clinical symptoms, rather than examining broader daily functioning such as physical health, sleep quality, and social relationships.
“As part of my doctoral research, I had the opportunity to follow children with ADHD, their siblings, and a control group over time,” explained lead author Noa van der Plas, a postdoctoral researcher at Vrije Universiteit Amsterdam. “This cohort was followed throughout childhood, but the most recent comprehensive follow-up was 10 years ago.”
“Now that they are adults, we wanted to know how these children grew up,” van der Plas told Cypost. “While it is known that ADHD is associated with childhood difficulties and functional impairment, little is known about the long-term development of ADHD. Our aim was to investigate broad aspects of daily functioning in adulthood in people diagnosed with ADHD in childhood.”
To better understand the causes of difficulties in adulthood, researchers are examining biological family members of individuals with ADHD. Full siblings share about 50% of their genetic material and are usually raised by the same parents and in similar home environments. By evaluating siblings along with individuals with ADHD, researchers can separate genetic and environmental influences from risks directly related to the diagnosis itself.
The authors evaluated data from an 18-year prospective study from a Dutch cohort. The sample included 154 adults diagnosed with childhood ADHD (mean 28.7 years, 68% male), 138 siblings without childhood ADHD (mean 29.6 years, 35% male), and 129 controls (mean 28.2 years, 40% male) with no family history of ADHD. On average, the researchers re-evaluated participants 17.6 years after they first entered the study in childhood.
To collect comprehensive data, participants completed a self-report online survey and standardized clinical interview over a secure video call. Participants also designated a close friend, partner, or parent to complete an observer questionnaire to provide an outside perspective on their daily activities. The assessment assessed seven major areas of adult life: mental status, behavioral and emotional problems, educational and occupational history, daily adaptive functioning, neurocognitive abilities, physical health, and health care utilization.
Statistical analysis revealed that adults diagnosed with childhood ADHD performed worse than control participants on more than 60% of the measures. Regarding mental status, 45% of participants in the pediatric ADHD group fully met diagnostic criteria for adult ADHD at follow-up. Among adults with childhood ADHD, 18% were diagnosed with major depressive disorder, compared with 8% of controls and 6% of siblings.
“Children with ADHD are at increased risk of problems in functioning as adults, including problems related to mental health, social functioning, and daily living,” van der Plas noted. “Notably, adults with childhood ADHD had a higher risk of developing major depressive disorder in adulthood.”
Behavioral assessments showed that adults with childhood ADHD report higher levels of externalizing problems, with externalizing difficulties such as impulsive or aggressive behavior. They also reported higher levels of autistic traits, mood dysregulation, physical aggression, and social aggression compared to control participants. In the area of education, individuals with childhood ADHD had lower average levels of formal education and lower performance on neurocognitive measures of working memory and verbal fluency.
On measures of adaptive functioning and physical health, adults with childhood ADHD reported higher perceived stress and lower mental well-being. They also had higher average body mass indexes, poorer sleep quality, and lower adherence to dietary guidelines set by the National Center for Nutrition. Furthermore, adults in the childhood ADHD group were significantly more likely to be currently prescribed ADHD medications compared to both siblings and control participants.
The sibling group showed similar adult functioning to the control group on most measures. “During childhood, siblings of children with ADHD are at increased risk for ADHD-related traits and exhibit intermediate neurocognitive profiles compared to controls,” van der Plas explained. “Based on these findings, we expected that siblings would also show more difficulties in adult functioning. However, there were few differences between siblings and controls in adulthood.”
Siblings had slightly elevated levels of self-reported ADHD and autistic traits and slightly higher BMI compared to controls, but no major psychiatric or academic setbacks. “Finally, although siblings of children with ADHD share half of their genetic material and some of their childhood environment, these siblings generally did not have an increased risk of developing problems as adults,” van der Plas said.
When comparing individuals whose ADHD persisted into adulthood and those whose symptoms remitted, certain patterns emerged. The persistent ADHD group had the highest risk of major depressive disorder, internalizing problems, severe stress, and poor sleep quality. However, even adults with remitted childhood ADHD showed lower educational attainment and lower cognitive scores than control participants, suggesting long-term effects on learning.
The researchers highlighted that despite overall group differences, there is considerable variation in how adults with childhood ADHD cope. “However, there is variability in the functioning of adults with childhood ADHD, with the majority of adults with childhood ADHD demonstrating comparable functioning to controls,” van der Plas told PsyPost. “Some adults with childhood ADHD seem to have particularly impaired functioning, and this appears to be partly related to continuing to be diagnosed with ADHD.”
The authors highlighted important misconceptions that the public should avoid when viewing this research. “On average, adults diagnosed with ADHD in childhood are more likely to experience functional difficulties, but most function as well as people without ADHD,” van der Plas added.
Several limitations should be considered when evaluating these results. The study sample consisted exclusively of people of Caucasian descent living in the Netherlands, which limits the extent to which the conclusions apply to more diverse racial and cultural populations. Only a portion of the original childhood cohort was successfully reassessed, resulting in selective participant dropout over an 18-year period.
The group that retained childhood ADHD had slightly higher severity of childhood symptoms than the group that dropped out. In other words, the results may reflect outcomes for individuals with slightly more severe initial symptoms. Additionally, the cognitive testing was conducted remotely via video call rather than in a standardized physical laboratory, so there may be some variance in the home testing environment.
“Other studies in my doctoral research further investigated specific medication outcomes, gender and sex differences in long-term outcomes of childhood ADHD, and long-term outcomes of childhood stimulant treatment, and sought to identify predictors of long-term outcomes,” van der Plas said of his broader research goals. “Future research should investigate risk and protective factors associated with differences in functioning in adults with childhood ADHD and identify which individuals are most at risk,” Professor van der Plas concluded. “This knowledge can help improve prevention and intervention strategies.”
The study, “Growing Up with ADHD: Findings from an 18-year longitudinal follow-up study of adults with childhood ADHD, their siblings, and controls,” was authored by Noah E. van der Plas, Siri DS Noedermeer, Barbara Franke, Katharina A. Hartmann, Peter J. Hoekstra, Nanda NJ Rommerse, Emma Slooten, Marjoline Luhmann, and Jaap. Oosterlaan.
