Adult ADHD
Visual Abstract
Is Adult ADHD a Childhood-Onset Neurodevelopmental Disorder? Evidence From a Four-Decade Longitudinal Cohort Study
Does Adult ADHD start during childhood?
Terrie E Moffitt , Renate Houts , Philip Asherson , Daniel W Belsky , David L Corcoran , Maggie Hammerle , HonaLee Harrington , Sean Hogan , Madeline H Meier , Guilherme V Polanczyk , Richie Poulton , Sandhya Ramrakha , Karen Sugden , Benjamin Williams , Luis Augusto Rohde , Avshalom Caspi
Summarized by:
April 22, 2023
study source
Am J Psychiatry
Oct 2015
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Does adult ADHD exclusively start during childhood, or can it also arise later in life?
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This study found that most with adult ADHD did not have it as children, and most children with ADHD no longer had it as adults.
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These two groups were also different in genetic testing. Only the childhood ADHD group showed known genetic risk factors for ADHD.
Is Adult ADHD a Childhood-Onset Neurodevelopmental Disorder? Evidence From a Four-Decade Longitudinal Cohort Study
Objective
Experts have traditionally assumed that adult ADHD is an extension of childhood ADHD. Under this theory, those who have adult ADHD most likely develop it as children.
However, there have not been many long-term studies backing this assumption.
This study aimed to test this theory by following a group of children to adulthood to see how childhood ADHD evolves and whether adults with ADHD had ADHD as children.
Study Quote
Despite a prevailing assumption that adult ADHD is a childhood-onset neurodevelopmental disorder, no prospective-longitudinal study has described the childhoods of the adult-ADHD population. We report follow-back analyses of ADHD cases diagnosed in adulthood, alongside follow-forward ana...
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Method
Researchers followed 1037 individuals in New Zealand from birth to age 38. They conducted extensive examinations, interviews, and genetic studies. They also surveyed parents and teachers to get outside data on whether a child had ADHD.
They conducted separate testing for adult ADHD as participants reached adulthood.
Study Quote
Participants belonged to a representative birth cohort of 1,037 individuals born in Dunedin, New Zealand in 1972-73 and followed to age 38, with 95% retention. Symptoms of ADHD, associated clinical features, comorbid disorders, neuropsychological deficits, GWAS- derived polygenic risk, a...
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Results
Researchers found that around 90% of adult ADHD cases do not have ADHD as children. Because the study was a long-term study, researchers were able to look back into the history of each case of adult ADHD to see whether they had ADHD as children.
The extensive testing conducted by researchers did not find evidence of childhood ADHD in most of the cases of adult ADHD.
This suggests that adult ADHD is not simply an extension of childhood ADHD. Instead, it may be a separate condition that can develop in adulthood.
Similarly, most children with ADHD did not appear to have ADHD when they reached adulthood.
A longitudinal study found that there was little overlap between child ADHD and adult ADHD
When researchers analyzed the genetic testing results, they found that the group with childhood ADHD, as a whole, had known genetic risk factors for ADHD.
However, the group with adult ADHD did not have these genetic risk factors.
This suggests that even genetically, adult ADHD and child ADHD may be two separate conditions.
Study Quote
As expected, the childhood-ADHD group showed 6% prevalence, male excess, childhood comorbid disorders, neurocognitive deficits, polygenic risk, and, despite having outgrown their ADHD diagnosis, residual adult life impairment. As expected, the adult-ADHD group showed 3% prevalence, gende...
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Conclusions
This study was one of the first to suggest that adult ADHD might be more than just an extension of child ADHD. In some cases, it could be a separate condition unconnected with childhood symptoms.
This was a relatively small study, and more research is needed before we know with certainty. But, if the findings in the study are true, they support reconsidering how we classify adult ADHD and researching how ADHD arises in adulthood.
Study Quote
Findings raise the possibility that adults presenting with the ADHD symptom picture may not have a childhood-onset neurodevelopmental disorder. If this finding is replicated, then the disorder's place in the classification system must be reconsidered, and research must investigate the et...
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