Does ADHD compound dementia's burden?

The study suggests yes. Among participants who developed cognitive impairment, those who also carried an ADHD diagnosis reported worse mental health, lower quality of life and less social satisfaction than those with dementia alone. They also used about 20% more health care overall in the year following diagnosis.

"We're replicating a pattern that's been observed in other countries, now in a large U.S. sample, and adding genetic evidence on top of it," said Douglas Teixiera Leffa, M.D., Ph.D., who recently completed his psychiatry residency at UPMC. "That combination gives us more confidence that ADHD deserves a closer look as a potential factor in cognitive aging."

Could the link be explained by misdiagnosis?

One concern is that early, undetected dementia symptoms might be mistaken for ADHD before a formal cognitive diagnosis arrives. The researchers tested this by requiring at least eight years to pass between an ADHD diagnosis and the onset of cognitive impairment. The association remained statistically significant, making that explanation less likely to account for the full effect.

What still isn't known?

Several questions remain open. The study could not determine whether ADHD medications, such as stimulants, lower dementia risk over time. It also could not clarify whether managing cardiovascular health — already linked to both ADHD and dementia — would help. Co-first author Guilherme Bauer-Negrini, Ph.D., a postdoctoral associate in biomedical data science at Pitt, said combining genetic information with years of health records lets researchers detect patterns that smaller, more traditional studies would miss — and could eventually point to modifiable factors that support healthier cognitive aging.

How strong is this evidence?

The All of Us sample is large and demographically diverse, but observational studies cannot prove causation. The findings build on a 2022 study from the Pascoal lab that first linked ADHD genetic risk to brain changes tied to Alzheimer's in cognitively unimpaired older adults. This new analysis is the largest to combine clinical diagnoses and genetic data within the same population.

Publication: Attention-Deficit/Hyperactivity Disorder and Late-Life Cognitive Impairment, JAMA Psychiatry (2026). DOI: 10.1001/jamapsychiatry.2026.3165.