People with ADHD four times more likely to develop dementia in old age, major study suggests

People with attention deficit hyperactivity disorder – ADHD – are significantly more likely to develop dementia, a study suggests.

Thought to affect 2.5million Britons, it could also heighten the chances of memory problems by four fold.

Experts suggest this could be down to a number of factors associated with the condition, such as poor diet, sleep problems and physical inactivity and known risk factors to memory.

Researchers from the University of Pittsburgh tracked 187,341 older adults over ten years, of which 3,026 had an ADHD diagnosis.

They found 6.7 per cent of those with ADHD went on to develop memory problems – defined as either a dementia diagnosis or mild cognitive impairment – compared to 3.4 per cent without.

When they conducted a more in-depth analysis to account for age, they saw the increased risk double to four-fold. 

When looking only at those with dementia diagnoses, the increased risk was three-fold. 

While mild cognitive impairment can be a precursor to dementia, the disease does not always develop. It is a term used to describe problems with memory and thinking that aren't severe enough to warrant a diagnosis.

People with ADHD may be up to four times more likely to develop dementia or memory problems in later life than those without the disorder, a major study claims

Everyone experiences dementia differently. Use this checklist to help you make a note of your symptoms before you talk to your GP.

The three-fold risk held true even after scientists adjusted for other factors that could explain the link, like physical and mental health conditions, education levels, smoking, and healthcare use.

The study is not the first to link ADHD and dementia. 

Separate research published in 2023 in the journal JAMA Network Open also found that adults diagnosed with ADHD had an almost three-times greater risk of developing dementia.

Investigations into what links the two are ongoing, but writing in the journal JAMA Psychiatry, the authors of the new study offered various theories.

One, they said, is that ADHD may be linked to lower 'cognitive reserve' – the brain's ability to complete tasks, particularly after ageing – due to the disorder's impact on memory and focus.

'A second hypothesis,' the authors continued, 'is that ADHD increases exposure to cumulative risk factors for cognitive impairment.'

These included chronic stress, sleep problems, physical inactivity, poor diet, risk of heart problems and substance use.

Crucially, the study was observational, meaning it cannot prove ADHD itself causes dementia. 

The researchers also stressed that some ADHD diagnoses could have reflected early, unrecognised symptoms of cognitive decline.

But they said their 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.

• For confidential advice, call Alzheimer's Society's Dementia Support Line on 0333 150 3456
• Alzheimer's Society's symptoms checker can help spot the signs of dementia
• READ MORE: How to spot if someone you love has warning signs of dementia