Study Finds Link Between Epilepsy and Early Dementia Risk

Individuals with epilepsy might face a higher risk of developing dementia before the age of 65. A large study analyzed data from hundreds of thousands of people in France and Sweden. The research identified a recurring presence of epilepsy among individuals later diagnosed with young-onset dementia, which occurs before 65 years of age. This study appears in Neurology, the journal of the American Academy of Neurology.

Dr. Rebecca Spiegel, a neurologist at Stony Brook Medicine, provided insights on the findings. She stressed caution, noting that seizures might represent early neurodegeneration in some patients. People with epilepsy could face cognitive challenges unrelated to dementia. Depression and anxiety are also notably high in this group.

Connection Between Epilepsy and Young-Onset Dementia

The study did not conclude that epilepsy directly causes young-onset dementia. Instead, it highlighted a significant association. Even though the relative increase in risk was significant, the likelihood of developing young-onset dementia remains low. This form of dementia, less common than its later-onset counterpart, impacts people during prime working years and family responsibilities.

To explore the link with epilepsy, researchers used national health databases in France and Sweden. The study had two main parts. One part looked backward, examining if those with young-onset dementia had earlier epilepsy diagnoses or medications. The second part followed individuals with epilepsy to see if they later developed dementia.

In France, researchers compared 11,360 patients with young-onset dementia and 113,600 dementia-free individuals of similar age and sex. In Sweden, comparisons involved 16,433 patients with young-onset dementia and 164,330 without it. The analyses in both countries revealed notable differences.

In France, 12.5% of young-onset dementia patients were previously diagnosed with epilepsy, contrasting with 1.2% of those without dementia. Additionally, 27.3% of those with dementia received epilepsy medications, compared to 10.3% of those without. Swedish data also showed similar patterns.

Tracking Over Time

The study also tracked newly diagnosed French adults with epilepsy, aged 30 to 55, from 2008 over a decade. During follow-up, 2.2% of these individuals developed young-onset dementia. This compares to 1.7% among those with existing epilepsy and 0.2% without epilepsy.

After adjusting for factors influencing dementia risk, including stroke and mood disorders, researchers found that newly diagnosed epilepsy patients were six times more likely to develop young-onset dementia. Existing epilepsy patients were 74% more likely than those without the condition.

The study had limitations. The databases didn’t detail dementia types, epilepsy forms, or causes. Researchers also noted that findings from France and Sweden may not reflect populations in other countries or healthcare settings.

This research adds to evidence linking epilepsy and cognitive decline. More studies are needed to explore why this connection exists and whether reducing epilepsy risks could lower early dementia chances.

“The reassuring message is that, despite the increased relative risk, the vast majority of patients with epilepsy in this study did not develop young-onset dementia,” Spiegel noted. “Nevertheless, the findings should encourage greater attention to cognitive assessment in people with epilepsy.”

The study is detailed in the reference work by Calonge et al., 2026 in Neurology.