A new study has found adults diagnosed with attention deficit hyperactivity disorder (ADHD) are almost three times more likely to develop dementia later in life.

The study, which was published in the journal JAMA Network Open, looked at 109,218 adults with and without ADHD over a period of 17 years. 

The researchers found 13.2 percent of the participants with ADHD went on to develop dementia over the course of the study, compared with 7 percent of those without an ADHD diagnosis. Even after adjusting for other potential factors, such as heart problems, the researchers found those with ADHD were 2.77 times more likely to develop dementia. 

The study’s findings are significant because they offer new insights into the potential link between ADHD and dementia. While the study doesn’t prove ADHD causes dementia directly, it does suggest a strong relationship between the two conditions. 

The researchers believe the neurological processes which underlie ADHD may also impact the brain’s ability to protect against cognitive decline later in life. They noted while the data showed adults with ADHD who took psychostimulants were not at a greater risk of developing dementia, more research is needed to confirm this finding. 

The study’s authors say the findings could help to identify people who are at increased risk for dementia, so they can be monitored more closely and take steps to reduce their risk. 

Neurologist Michal Schnaider Beeri, who assisted with the research, indicated the results could assist with identifying who are at greater risk of dementia. 

“By determining if adults with ADHD are at higher risk for dementia and if medications and/or lifestyle changes can affect risks, the outcomes of this research can be used to better inform caregivers and clinicians,” he stated. 

Abraham Reichenberg, a brain and behaviour scientist who work on the research, agreed, noting the potential need for older people to be monitored for ADHD symptoms if the research’s hypothesis is found to be true.  

“Physicians, clinicians and caregivers who work with older adults should monitor ADHD symptoms and associated medications,” he said.  

The researchers have also said the findings could lead to new treatments for ADHD that could also help to lower the risk of dementia.