If you work in dementia care, you may have heard a startling claim recently: that people with ADHD are about three times more likely to develop dementia. It is the kind of number that sounds too neat to be true, so it deserves a proper look. Where does it come from, how solid is it, and what does it actually mean for the residents in your care? Here is the evidence, in plain English, including the parts that should make us careful.
The headline study
The number comes primarily from a 2023 study by Levine and colleagues, published in JAMA Network Open. The researchers followed more than 109,000 adults for seventeen years, comparing those with an adult ADHD diagnosis to those without. The results were striking: 13.2 per cent of the adults with ADHD went on to develop dementia, compared with 7 per cent of those without. After statistical adjustment, an adult ADHD diagnosis was associated with a nearly threefold increased risk.
This was not a small survey or a laboratory finding. It was a nationwide cohort study, which is about as strong as evidence gets short of a controlled trial, and for a question like this a controlled trial is impossible. You cannot randomly assign people to have ADHD.
The finding inside the finding
The most important detail in the study is one the headlines mostly missed. Among people with ADHD who received psychostimulant medication, the researchers found no clear increase in dementia risk at all.
Read that again, because it changes the meaning of everything. The risk factor may not be ADHD itself. It appears to be untreated ADHD. Researchers are still working out why. The leading explanations involve shared biological pathways: long-term dysregulation of dopamine, chronic inflammation in the brain, and what scientists call cognitive reserve, the brain's accumulated resilience against decline. Treatment may protect by normalising dopamine function across a lifetime. These mechanisms are plausible and actively studied, but not yet settled.
Why this lands directly on care homes
Now follow the logic through. ADHD affects an estimated 2.5 to 3 per cent of adults, yet in the UK only around one in nine people with the condition has a diagnosis, and today's older generation grew up decades before assessment existed at all. Almost no one in a care home today was ever diagnosed, which means almost no one was ever treated.
So the group carrying the highest risk in the research, people who lived their whole lives with untreated ADHD, is precisely the group now arriving in dementia care. Around 70 per cent of UK care home residents live with dementia or severe memory problems. If the evidence is pointing the right way, a meaningful share of those residents have both conditions, and their ADHD is invisible to everyone supporting them.
The honest caveats
Good science means saying what we do not know, so here are the limits. These studies show association, not proven causation; something else linked to ADHD could be driving part of the risk. The protective effect of medication was observed rather than tested in a trial, so "treatment prevents dementia" remains a hypothesis, not a fact. Diagnosing ADHD in older adults is genuinely difficult, because attention problems can also be an early sign of dementia itself, which can blur the numbers in both directions. And this field is young: the key studies are only a few years old, and the picture will sharpen.
Here is why those caveats should not become an excuse for doing nothing. In dementia care, the response to this evidence does not involve medication or diagnosis at all. It involves recognising lifelong traits and adjusting care around them: a quieter dining room, a reason given with every request, belongings kept in sight. If a resident's lifelong sensory sensitivity is ADHD, those adjustments help. If it turns out to be something else, those adjustments still help. The cost of acting on this evidence is low, and the cost of ignoring it is paid by residents, in distress that nobody understands.
What a care home can actually do
You cannot diagnose, and you should not try. What you can do is see. Look at the whole life history of the person in front of you: the many jobs, the unfinished projects, the lifelong lost keys, the labels they were given instead of help. The ADHDementia screening tool structures exactly that reflection and turns it into practical, person-centred adjustments. The full referenced paper behind this article, including the policy argument for treating adult ADHD as dementia prevention, is free to read on our research page.
The research will keep evolving. The residents are already here.