Epilepsy associated with increased risk of dementia before age 65

by American Academy of Neurology

edited by Sadie Harley, reviewed by Robert Egan

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People with epilepsy may be more likely to develop young-onset dementia than people without epilepsy, according to a study published in Neurology. Young-onset dementia, sometimes called early-onset dementia, develops before age 65. The study does not prove that epilepsy is a direct cause of young-onset dementia; it only shows an association.

"These results support integrating dementia prevention into the care of people with epilepsy," said study author Vincent Navarro, M.D., Ph.D., of Sorbonne University in Paris, France. "They may benefit from earlier assessments of their cognitive risks and intensified management of risk factors that can be modified, such as cardiovascular factors like high blood pressure."

Tracing epilepsy before dementia diagnoses

The study used two methods in two countries. One looked back in time to see whether people with dementia had previously been diagnosed with epilepsy or used epilepsy drugs. The other followed people with epilepsy over time to see if they were diagnosed with dementia.

Using national databases in France and Sweden, researchers looked at people who were diagnosed with young-onset dementia and matched them each with 10 people of the same age and sex who did not have dementia. Then they looked back to see whether people had been diagnosed with epilepsy or used epilepsy drugs up to 10 years before.

A total of 11,360 people with young-onset dementia were compared with 113,600 people without dementia in France. In Sweden, 16,433 people with young-onset dementia were compared with 164,330 people without dementia. In France, 12.5% of the people with dementia had an epilepsy diagnosis, compared with 1.2% of the people without dementia.

A total of 27.3% of those with dementia had received epilepsy medications, compared with 10.3% of those who did not have dementia. Those results were similar to those in Sweden.

Higher risk over 10 years

For the other study method, researchers identified French people ages 30 to 55 who were newly diagnosed with epilepsy in 2008 and compared them with people who already had epilepsy before 2008 or did not have epilepsy. Then those participants were followed for up to 10 years to see who developed young-onset dementia.

There were 12,901 people newly diagnosed with epilepsy, 64,083 with existing epilepsy and 129,010 people without epilepsy. Over 10 years, 2.2% of the newly diagnosed people developed young-onset dementia, compared with 1.7% of those with existing epilepsy and 0.2% of those without epilepsy.

After adjusting for other factors that could affect the risk of dementia, such as stroke, mood disorders and traumatic brain injury, people newly diagnosed with epilepsy were six times more likely to develop young-onset dementia than people without epilepsy. People with existing epilepsy were 74% more likely to develop dementia.

Absolute risk remains low

"Previous studies have shown a link between epilepsy and late-onset dementia, but limited evidence was available about young-onset dementia," Navarro said. "While these results show a strong relationship between epilepsy and young-onset dementia, it's important to remember that absolute risk is low."

A limitation of the study was that detailed information was not available on the type or cause of dementia cases and the type of epilepsy cases. In addition, the study was based on information from two high-income countries with universal health care coverage, so the results may not apply to other settings.

Publication details

Neurology (2026).

Journal information: Neurology

Key medical concepts

Epilepsy

Clinical categories

Neurology Provided by American Academy of Neurology Who's behind this story?

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →

Robert Egan

Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →

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