Age of onset and duration of dementia in people with down syndrome: Integration of 98 reported cases in the literature

The published case reports of 98 people with Down Syndrome were studied with respect to the age of onset and duration of clinically diagnosed dementia. The incidence of dementia was unimodal, increasing rapidly from 40 years to a peak of 30% incidence in the fifth decade of life, followed by a further rapid decline. Females with Down syndrome had an earlier onset. Duration of dementia decreased with increasing age of onset for both males and females.