Scientists reveal why people with the ApoE4 gene are more susceptible to Alzheimer's disease. Late-onset Alzheimer's disease--the subset of the disorder occurring in people age 65 and over--affects more than 5 million Americans, and is characterized by progressive memory loss and dementia. Scientists have put forth a variety of hypotheses on its causes, including the accumulation of protein clusters called beta-amyloid plaques and tau tangles in the brain.

Source: New mechanism discovered for Alzheimer's risk gene