Could epilepsy be an early warning sign of young-onset dementia?

Clinical takeaway: Consider earlier cognitive risk assessment as part of long-term care for adults with epilepsy, particularly those with cardiovascular disease or multiple comorbidities. While the absolute risk of young-onset dementia remains low (2.2% over 10 years among people with newly diagnosed epilepsy), epilepsy may help identify patients who could benefit from closer cognitive monitoring and intensified management of modifiable vascular risk factors.

Young-onset dementia (YOD), defined as dementia before age 65, is less common than late-onset dementia but often carries major social, occupational, and family consequences. Although epilepsy has been linked to dementia in older adults, its relationship with YOD has been less clear.

In a nationwide analysis of health data from France and Sweden published in Neurology, researchers found a consistent association between epilepsy and YOD across multiple study designs. In France, 12.5% of people diagnosed with YOD had a prior epilepsy-related diagnosis, compared with 1.2% of matched controls, and 27.3% had received antiseizure medications versus 10.3% of controls. A Swedish analysis of 16,433 YOD cases yielded similar findings.

The researchers also followed more than 205,000 French adults aged 30 to 55 for up to 10 years, including 12,901 people with newly diagnosed epilepsy, 64,083 with existing epilepsy, and 129,010 without epilepsy. Over the follow-up period, YOD developed in 2.2% of people with incident epilepsy and 1.7% of those with prevalent epilepsy, compared with just 0.2% of people without epilepsy.

After accounting for factors such as stroke, traumatic brain injury, psychiatric disorders, cardiovascular disease, and socioeconomic status, newly diagnosed epilepsy was associated with an approximately sixfold higher risk of YOD, while existing epilepsy was associated with more than fivefold higher risk.

The association weakened over time but remained nearly fourfold higher even after excluding dementia diagnoses occurring within the first 5 years after epilepsy onset, suggesting the relationship extends beyond a purely prodromal effect. The authors suggest shared vulnerability, such as cardiovascular disease, may play a role, and the study shows association, not causation.

Risk was highest among people with epilepsy and multiple coexisting conditions. Among patients with newly diagnosed epilepsy, 10-year YOD incidence ranged from 1.4% in those without baseline comorbidities to 9.1% in those with four or more comorbidities. The authors note that more frequent neurologic follow-up in people with epilepsy may have increased dementia detection.

“These results support integrating dementia prevention into the care of people with epilepsy,” said Vincent Navarro, MD, PhD, of Sorbonne University. “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.”

Sources: Calonge Q, et al. (October 14, 2026) Neurology. Association Between Epilepsy and Young-Onset Dementia: Nationwide Data From France and Sweden