Late Onset Seizures Dementia Risk in Older Adults

What was studied

Researchers used health records from the TriNetX Global Collaborative Network to study adults age 65 or older who had cardiometabolic or vascular conditions. They compared people with a new late-onset unprovoked seizure of unknown cause with people who had syncope (fainting) but no seizure diagnosis.

After matching the groups on 28 measured baseline factors, each group included 40,401 people. The researchers examined dementia-related diagnoses and death over 5 years, with an additional analysis extending to 10 years.

What they found

Within 5 years, all-cause dementia was diagnosed in 14.5% of people with late-onset unprovoked seizures and 10.0% of the comparison group. The seizure group had a 55% higher hazard of dementia during follow-up.

Late-onset unprovoked seizures were also associated with higher hazards of Alzheimer's disease, vascular dementia, mild cognitive impairment, non-Alzheimer's dementia, and death from any cause. The largest dementia-subtype association was with vascular dementia, for which the hazard was about twice as high. The overall dementia association was similar in subgroup, sensitivity, lagged, and 10-year analyses.

Limits of the evidence

This was an observational health-record study, not a randomized trial. Matching made the groups more comparable on measured factors but cannot eliminate all differences, so the study cannot establish that seizures cause dementia or determine the direction of the relationship.

Dementia subtypes were identified from diagnostic codes rather than confirmed with biomarkers, so subtype-specific estimates should be interpreted cautiously. The main analysis focused on older adults with cardiometabolic or vascular conditions, although an analysis with broader eligibility produced similar results.

For families and caregivers

A new unprovoked seizure with no identified cause in later life may identify an older adult who is at increased risk of later cognitive problems. This does not mean that every older person with such a seizure will develop dementia, or that the seizure itself caused dementia. The findings support closer follow-up for changes in memory, thinking, and daily function.

What to watch next

Further research is needed to clarify the direction of the relationship between late-onset unprovoked seizures and dementia and to confirm dementia subtypes using evidence beyond diagnostic codes, including biomarkers.

Terms in this summary

Late-onset unprovoked seizure

A seizure that begins later in life without an immediate trigger; in this study, no underlying cause was identified.

Dementia

A decline in memory or other thinking abilities that interferes with everyday life.

Mild cognitive impairment

Noticeable problems with memory or thinking that are greater than expected for age but do not yet substantially interfere with independence.

Vascular dementia

Cognitive decline associated with reduced blood flow, strokes, or other damage to blood vessels in the brain.

Propensity score matching

A statistical method used to create comparison groups with similar measured characteristics.

Hazard ratio

A comparison of the rate at which an outcome occurs over time. A value above 1 indicates a higher hazard in one group.

Target trial emulation

A framework for designing an observational analysis to resemble a hypothetical randomized trial, although participants are not actually randomized.

Biomarker

A measurable biological sign that may help support or confirm a disease diagnosis.