Although seizures are more likely in people with Alzheimer disease (AD) than in the general population, they are not a common feature of AD, new research indicates.

In a study, researchers found that only about 1.5% of patients with AD developed seizures over an average of 3.7 years. The observed incidence corresponds to less than 1 patient with a seizure for every 200 patients with AD followed up over the course of 1 year, they point out in the Archives of Neurology this month.

And while earlier reports suggested that seizures occur in more advanced stages of the disease, there was no association in the current study between seizures and disease duration or brain function.

In the study, Dr. Nikolaos Scarmeas, from Columbia University Medical Center, New York, and colleagues followed 453 patients from the early stages of AD for up to 14 years (average, 3.7 years). The patients were in generally good health, well educated and mostly white. Their average age at the outset was 74 years.

During follow-up, 7 patients (1.5%) developed seizures.

The overall incidence of seizures was low, the researchers report, although significantly higher than expected for unprovoked seizures in age-matched people in the general population.

According to the investigators, only younger age was associated with higher seizure risk.

Scarmeas and colleagues suggest that younger patients with AD may have more aggressive disease, or may be more likely to have a clinical episode recognized.

Alternatively, the younger brain may be more susceptible to seizures.

SOURCE: Archives of Neurology, August 2009.

New York Medicine