Epilepsy Linked to Higher Risk of Dementia Before Age 65, Study Finds

Much of the research tying epilepsy to dementia has looked at people in their later years.

A new study from France and Sweden turns to a younger group, asking about dementia that develops before age 65, and one of its numbers is hard to ignore: six times.

That figure comes from a paper published October 14 in Neurology, and it applies to one particular group of people with epilepsy, not all of them. The same study also reports how many people in that group actually developed dementia, a far smaller number, and putting the two side by side changes how the headline reads. Then there’s the question researchers haven’t settled. Epilepsy may come first, dementia may come first, or something else may be driving both.

Earlier work points in more than one direction, and some of it involves seizures that barely look like seizures at all.

Newly Diagnosed Patients Stood Out

One specific group drove the biggest jump.

To follow people forward in time, researchers in France identified adults aged 30 to 55 who were newly diagnosed with epilepsy in 2008. That group of 12,901 people was compared with 64,083 who already had epilepsy before 2008 and 129,010 who didn’t have it. Everyone was tracked for up to 10 years.

After accounting for factors that can affect dementia risk, including stroke, mood disorders, and traumatic brain injury, the newly diagnosed group was six times more likely to develop young-onset dementia than people without epilepsy.

People who already had epilepsy were 74% more likely. The study doesn’t explain why the link was stronger soon after diagnosis.

The Actual Odds Were Much Smaller

A multiplier can make a modest risk sound enormous.

Over the 10 years, 2.2% of the newly diagnosed group developed young-onset dementia. The figure was 1.7% for people with existing epilepsy and 0.2% for people without it.

Those are the outcomes researchers observed; the sixfold and 74% numbers come from the adjusted comparison, which is why you can’t get from one set to the other with simple division.

Study author Vincent Navarro, MD, PhD, of Sorbonne University in Paris, put it this way: “While these results show a strong relationship between epilepsy and young-onset dementia, it’s important to remember that absolute risk is low.”

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The Study Looked Backward, Too

A second approach started with dementia and worked in reverse.

The French follow-up was only part of the work. Using national databases, researchers identified 11,360 people in France and 16,433 in Sweden who had been diagnosed with young-onset dementia.

Each was matched with 10 people of the same age and sex who didn’t have dementia, and the team checked for an epilepsy diagnosis or epilepsy medication in the years before.

In France, 12.5% of the people with dementia had an earlier epilepsy diagnosis, compared with 1.2% of those without. The Swedish results were similar.

Because these groups were chosen by dementia status, the percentages can’t tell you how many people with epilepsy go on to develop dementia.

Which Condition Comes First Is Still Unsettled

Earlier research suggests the relationship may run in both directions.

A 2020 analysis of the Framingham Heart Study found that people with dementia had about 1.8 times the risk of later developing epilepsy, while people with epilepsy had roughly twice the risk of later developing dementia. That work followed dementia after age 65, so it adds context without replacing the new numbers.

A 2025 scientific review adds another wrinkle. Epilepsy has long been treated as a late consequence of Alzheimer’s disease, but newer research places seizures earlier in the process, sometimes before memory symptoms appear. An epilepsy diagnosis that comes first, then, doesn’t tell you which condition set things in motion.

The new study also isn’t arriving in a vacuum. A 2026 meta-analysis of 36 studies rated the evidence for an epilepsy link to young-onset dementia as suggestive, a step below its two stronger categories. Stroke earned the strongest rating.

Seizures Can Hide In Plain Sight

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The ones tied to dementia often skip the dramatic collapse.

Most seizures in people with dementia are focal-onset seizures, which don’t always involve falling or shaking. They can look like a short spell of unresponsiveness, a brief worsening of memory, or repetitive movements such as chewing, lip-smacking, or swallowing, and the person usually returns to normal fairly quickly. Those descriptions come from people who already have dementia, so they’re no screening checklist.

The overlap has also inspired treatment experiments. A 2021 randomized trial gave the antiseizure drug levetiracetam to 34 adults with Alzheimer’s and found no significant improvement on its main cognitive measure. An exploratory analysis showed gains on some executive-function and spatial-memory tasks among people with seizure-like brain activity. However, the authors warned the small sample left room for false positives.

What This Could Change For Patients

The study author thinks epilepsy care could start paying attention to the brain sooner.

Navarro says the findings support building dementia prevention into epilepsy care. He suggests people with epilepsy may benefit from earlier assessments of their cognitive risks and closer management of factors that can be changed, including high blood pressure. That’s his proposal; the study doesn’t create a guideline or recommend changing epilepsy medication.

The researchers didn’t have detailed information on epilepsy type or on dementia type and cause. A 2024 study of 146 people with newly diagnosed late-onset epilepsy, a mostly older group, shows why that matters: those whose epilepsy was presumed to have a neurodegenerative cause had the poorest cognitive trajectory, while many people in the other groups were stable or improved after 12 months of retesting.

Both countries in the new study are high-income places with universal health care, so the results may not carry over everywhere, and there’s no U.S.-specific risk estimate. Whether acting on Navarro’s suggestions would actually change outcomes for people with epilepsy is something the study didn’t test.

When you hear the word “seizure,” what do you picture, and did anything here change that image?