Interestingly, there was no increased risk of dementia in adults with ADHD who took stimulants, like Adderall or Concerta, to manage the condition. That may be because stimulants are known to improve cognitive impairment, researchers wrote. 

Additionally, because ADHD is a chronic condition, there may be negative long-term effects if left untreated. If this is the case, perhaps it is untreated ADHD that puts patients at higher risk—not the lack of stimulant use per se.

“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,” said Michael Schnaider Beeri—director of the Herbert and Jacqueline Kriger Klein Alzheimer’s Research Center at Rutgers Brain Health Institute, and a coauthor on the paper—in a news release about the study.

The ADHD-dementia link

Researchers from the University of Haifa in Israel, Rutgers University in New Jersey, and others examined the medical records of nearly 110,000 Israelis who were between ages 51 and 70. None of them had a diagnosis of ADHD or dementia when monitoring began in 2003. About half were male, and about half were female.

In the 20-year period that followed, 0.7% of adults received a diagnosis of ADHD, and 7.1% received a diagnosis of dementia. Among those with ADHD, dementia occurred in 13.2%. Among those without ADHD, dementia occurred in only 7%. 

After adjusting for other factors that might influence dementia risk—like the presence of cardiovascular disease—researchers found that seniors with ADHD were at a 2.77-fold increased risk of developing dementia. That may be because adults with ADHD have reduced ability to cognitively compensate for later-in-life neurodegeneration, the authors speculated.

Stephen Levine, a professor at the School of Public Health at the University of Haifa and lead author on the paper, said the paper is proof that “symptoms of attention deficit and hyperactivity in old age shouldn’t be ignored and should be discussed with physicians.”

Multiple other studies—though not all—have come to similar conclusions. For instance, a 2022 study published in European Psychiatry found that people with ADHD were at a higher risk for dementia and mild cognitive impairment, though that risk decreased when the findings were adjusted for psychiatric disorders like depression, anxiety, substance abuse use disorder, and bipolar disorder. 

The link between ADHD and dementia was stronger in men than in women, researchers found. They also found that metabolic disorders, sleep disorders, history of head injuries, educational attainment, and other developmental disorders had little impact on whether one developed dementia or not.

How ADHD and dementia overlap

ADHD is a neurodevelopmental disorder that usually, but not always, develops in childhood, and can persist into adulthood. 

Symptoms include:

• Failing to pay close attention to details or making careless mistakes at school, work, or in other activities
• Difficulty maintaining attention
• Often fails to finish tasks
• Often has trouble organizing tasks and activities
• Often loses necessary items, like books, pencils, wallets, keys, paperwork, eyeglasses, and phone
• Easily distracted
• Forgetful of daily activities
• Often fidgets or squirms while sitting
• Often talks excessively

Dementia is a neurodegenerative disorder that almost exclusively occurs in the elderly, with a wide range of possible symptoms, including:

• Memory loss
• Poor judgment
• Confusion
• Getting lost
• Trouble handling money and paying bills
• Taking longer to complete daily tasks
• Acting impulsively
• Losing balance

Both conditions present with cognitive deficits and/or changes in behavior, according to a 2023 article in Progress in Neurology and Psychiatry. People with either condition are more likely to have sleep disturbances, depression, and/or anxiety, all of which may contribute to their symptoms.

While some experts speculate that ADHD puts someone at higher risk for dementia, others view ADHD as one point along a continuum, with dementia further to the right.