Adults with attention deficit hyperactivity disorder (ADHD) may face a substantially higher risk of developing dementia later in life, according to new research.
The condition is thought to affect around 2.5 million people in Britain and may be associated with up to a fourfold increase in the likelihood of memory-related problems.
Researchers believe the connection could involve several factors commonly linked with ADHD, including disrupted sleep, an unhealthy diet and low levels of physical activity — all of which are also recognised risks for cognitive decline.
A team from the University of Pittsburgh followed 187,341 older adults for a decade. Among them, 3,026 had received an ADHD diagnosis.
During the study period, 6.7 per cent of participants with ADHD developed memory problems. This category included either a dementia diagnosis or mild cognitive impairment, compared with 3.4 per cent of people without ADHD.
After carrying out a more detailed analysis that accounted for age, the researchers found the relative risk rose to between two and four times higher among those with ADHD.
Looking specifically at dementia, rather than memory problems overall, people with ADHD were found to have about three times the risk.
Mild cognitive impairment can sometimes precede dementia, although it does not inevitably progress to the disease. The term refers to difficulties with memory or thinking that are noticeable but not severe enough to meet the criteria for dementia.
People with ADHD may be up to four times more likely to experience dementia or other memory problems in later life than those without the condition, according to a major study
Dementia affects everyone differently. This checklist can help you record any symptoms before discussing them with your GP.
The threefold increase in dementia risk remained even after the researchers accounted for other possible influences, including physical and mental health conditions, education, smoking and use of healthcare services.
The latest findings add to growing evidence linking ADHD with dementia and other forms of cognitive decline.
Research published in 2023 in JAMA Network Open similarly reported that adults with an ADHD diagnosis had an almost three times greater risk of developing dementia.
Scientists are still investigating why the conditions may be connected. Writing in JAMA Psychiatry, the authors of the new study outlined several possible explanations.
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One possibility is that ADHD may be associated with reduced “cognitive reserve” — the brain’s ability to cope with ageing or damage while continuing to perform mental tasks. Difficulties with concentration and memory linked to ADHD could contribute to this lower reserve.
The researchers also suggested that ADHD may increase a person’s long-term exposure to factors known to affect cognitive health.
Those factors include chronic stress, poor sleep, inactivity, an unhealthy diet, cardiovascular risks and substance use.
However, the study was observational, so it cannot establish that ADHD directly causes dementia.
The researchers also acknowledged that some ADHD diagnoses may have represented early, undetected signs of cognitive decline rather than a separate underlying condition.
Even so, they said the findings “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.
The Daily Mail 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.