People with attention deficit hyperactivity disorder (ADHD) may face a substantially higher risk of developing dementia later in life, according to new research.
The condition, estimated to affect 2.5 million people in Britain, was also associated with up to a fourfold increase in the likelihood of experiencing memory problems.
Researchers say several factors linked to ADHD could help explain the connection, including an unhealthy diet, disrupted sleep and low levels of physical activity—all of which are recognised risks for cognitive decline.
Scientists at the University of Pittsburgh followed 187,341 older adults for a decade. Among them, 3,026 had been diagnosed with ADHD.
During the study, 6.7 per cent of participants with ADHD developed memory problems. This included either a dementia diagnosis or mild cognitive impairment, compared with 3.4 per cent of those without ADHD.
After the researchers adjusted their analysis for age, the difference became more pronounced, with ADHD linked to a twofold to fourfold higher risk of memory problems.
Looking specifically at dementia diagnoses, the risk among people with ADHD was three times higher.
Mild cognitive impairment can precede dementia, although it does not always progress to the disease. The term describes difficulties with memory or thinking that are noticeable but not severe enough to meet the criteria for a dementia diagnosis.
A large study suggests that people with ADHD could be up to four times more likely to develop dementia or memory problems in later life than those without the disorder
Dementia affects everyone differently. This checklist can help you record any symptoms before discussing them with your GP.
The threefold dementia risk remained even after the scientists accounted for other possible influences, including physical and mental health conditions, education, smoking and use of healthcare services.
The findings add to previous research linking ADHD with dementia.
A separate study published in JAMA Network Open in 2023 reported that adults diagnosed with ADHD had almost three times the risk of developing dementia.
The precise relationship remains under investigation. Writing in JAMA Psychiatry, the researchers behind the latest study outlined several possible explanations.
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One possibility is that ADHD is associated with a lower level of “cognitive reserve”—the brain’s ability to cope with tasks and maintain function, particularly as people age—because the condition can affect memory and concentration.
The authors also proposed that ADHD may lead to greater long-term exposure to factors known to contribute to cognitive impairment.
These factors include chronic stress, sleep difficulties, physical inactivity, poor diet, cardiovascular risks and substance use.
However, the study was observational, so it cannot show that ADHD itself causes dementia.
The researchers also cautioned that some ADHD diagnoses may have represented early, undetected signs of cognitive decline.
Even so, they said the results “support ADHD as a relevant factor in later-life cognitive health”.
A connection between physical and brain health has long existed.
A healthy lifestyle is known to reduce the risk of developing dementia in later life, according to the NHS.
This includes eating a balanced diet, exercising, maintaining a healthy weight, not smoking, keeping blood pressure at healthy levels, and not drinking alcohol excessively.
Almost one million Britons are living with dementia, which claims 76,000 lives a year as Britain’s biggest killer.
Our News Outlet and Alzheimer’s Society have partnered in a drive to defeat dementia with its Defeating Dementia Campaign, which aims to increase early diagnosis, boost research and improve care.
Of the 2.5million people in England believed to have ADHD, there are about 741,000 children and young people aged five to 24.
Diagnoses of the disorder have risen 20-fold over two decades, figures show.
