Clinical and epidemiological aspects of Alzheimer's disease with presenile onset: a case control study.

Little is known regarding the pathogenetic factors for Alzheimer's disease (AD). We studied 63 AD patients in order to evaluate if there were clinical subtypes of AD and whether prior illnesses and life-styles were involved in the development of the disease. In our patients selected for onset of symptoms before age 65 we did not find any significant clinical heterogeneity. Furthermore, we found no data in the medical history that are predictive for the development of presenile AD but observed a significantly increased frequency of dementia in the families of AD patients in comparison to controls.