Adults over 50 with an ADHD diagnosis got a diagnosis of mild cognitive impairment or dementia roughly twice as often as other adults over the following decade or so, according to a JAMA Psychiatry study of 187,341 people published online October 7. The authors are quick to say the data can’t show that ADHD causes dementia. Most of the people with ADHD in the study never developed a cognitive problem at all.
Tharick Pascoal, who led the work at the University of Pittsburgh, saw a similar pattern in two kinds of data. It turned up in records and genetic data alike. He says that makes a quirk in who gets diagnosed a less likely explanation.
Adults With ADHD Got Cognitive Diagnoses Twice As Often
The researchers pulled health records and genetic information from the All of Us Research Program, a large NIH-run database, then compared adults with and without an ADHD diagnosis.
- 187,341 adults aged 50 and older took part, and 3,026 of them had ADHD.
- 6.7% of the people with ADHD later got a diagnosis of mild cognitive impairment or dementia, against 3.4% of everyone else.
- Most of those diagnoses were mild cognitive impairment, with the dementia-only estimate resting on fewer cases.
- People with the highest genetic scores for ADHD had 35% greater odds of dementia than people with the lowest scores.
About 93 in 100 adults with ADHD in this group went without a cognitive diagnosis, so the finding describes a shift in odds and says nothing certain about any one person.
A Hazard Ratio Compares Rates Over Time, So It Looks Bigger Than The Raw Percentages
Headlines have said the risk was more than fourfold higher. The fourfold figure is a hazard ratio of about 4.6 after adjusting for age, sex and other health conditions. It compares how quickly new diagnoses showed up in each group across the follow-up years. The raw 6.7% versus 3.4% is a plain share of each group, about double. The two numbers measure different things, though they come from one group of people.
The Link Got Weaker When Researchers Required A Longer Gap
Psychiatrist Ryan Sultán went through the paper’s sensitivity checks and points to the part that gets less attention. When the authors insisted on a longer and longer stretch between the ADHD diagnosis and the cognitive diagnosis, the hazard ratio dropped from 4.60 to 1.44 at an eight-year gap. By nine years it was no longer statistically significant. Some of that shrinkage comes from having fewer cases to count, as the authors acknowledge.
Sultán argues the pattern also fits a diagnosis problem. Plenty of adults get an ADHD diagnosis late, often after seeing a doctor about trouble concentrating. In some of them the early slide in thinking may have been the reason they went in. Mild cognitive impairment diagnoses depend a lot on the clinician. Standard memory screens also weren’t built for people who’ve been distractible their whole lives, so an ADHD trait can read as decline on paper.
Researchers Suspect Sleep, Stress And Heart Risks Explain Part Of The Link
The authors point to a stack of exposures that tend to pile up with ADHD: chronic stress, poor sleep, low physical activity, a weaker diet, heart and metabolic risk, injuries and substance use. Sultán notes that 10 of the 14 modifiable dementia risk factors in the 2024 Lancet Commission’s list are more common in people with ADHD. Another idea in play is cognitive reserve, the brain’s cushion against age-related change. In ADHD that cushion may be thinner, so symptoms would show up sooner. The study tested none of these ideas.
A small Geneva study of 32 adults with ADHD and 29 without found altered iron buildup in several brain regions and higher blood levels of neurofilament light chain, a marker of nerve damage. It offers an early signal in a young group and settles nothing about dementia.
Douglas Leffa, a psychiatrist and author of the paper, put the main point plainly: most people with ADHD did not develop cognitive impairment. Researchers haven’t tested if treating ADHD lowers later dementia risk. Leffa says there’s no convincing evidence yet that it does.
If You Have ADHD, Don’t Write Off New Memory Changes As Just ADHD
Doctors who weren’t involved in the study suggest a measured response. Thomas MacLaren, a consultant psychiatrist in London, stresses that a higher statistical risk doesn’t predict what happens to any individual. The practical advice is the ordinary brain-health list: regular exercise, decent sleep, blood pressure and cholesterol under control, no smoking, plus staying socially and mentally busy. Treating ADHD and any depression, anxiety or sleep disorder alongside it matters too.
The useful comparison is you against your own baseline, so a new change in memory or thinking is worth raising with a doctor even when ADHD has always been part of the picture.
A few gaps remain in what’s been published so far. The study is observational. Follow-up is described as roughly a decade in one account and left unstated in others. Funding isn’t mentioned in the coverage. For more on lowering dementia risk, an earlier look at how nearly half of dementia cases may be preventable is a good start. Research on why some brains resist Alzheimer’s damage adds the other side.
