Genetic epidemiology of Alzheimer's disease

Dementia is a major health problem in the elderly. It is a syndrome characterized by impairment in intellectual functioning resulting in a distressing condition both for the patient and caregiver. Alzheimer's disease (AD) is the most common cause of dementia in Western society. AD is clinically characterized by an insidous onset of decline in memory and at least one other area of cognition. Additional characteristics are a gradually progressive course, a preserved level of consciousness, and absence of other conditions able to cause these symptoms. The pathological hallmark in brains of AD patients are extracellular plaques composed mainly of the amyloid-p peptide and intracellular neurofibrillary tangles containing hyperphosphorylated tau protein (Braak and Braak, 1991).