Age of seizure onset in adults with Down's syndrome

In a cohort of 68 adults (35 males and 33 females) with Down's syndrome age d 29-83 years, a history of seizures was found in 26.5%. The overall mean a ge of onset of seizures was 37 years, males (22 years) being significantly younger than females (51 years). The age of onset was bimodally distributed , with the first peak occurring in the first two decades, and a late-onset peak occurring in the fifth and sixth decades. A strong association between Alzheimer's disease and seizures was confirmed. Of those with a history of seizures, those aged over 45 years were significantly more likely to devel op Alzheimer's disease than those younger than 45. It is suggested that lat e-onset epilepsy in Down's syndrome is associated with Alzheimer's disease, while early-onset epilepsy is associated with an absence of dementia.