What is the strongest risk factor for late-onset Alzheimer's disease?

• A. Family history
• B. Advancing age
• C. Head trauma
• D. ApoE4 genotype

Answer: (B)

Advancing age is the strongest risk factor for late-onset Alzheimer’s disease. The likelihood of developing Alzheimer’s increases markedly as people get older, with most cases occurring in those beyond midlife. Risk rises each year after 65, and by the time someone reaches their 80s or 90s, the chance is substantially higher than in younger adults. This pattern reflects the cumulative brain changes that accompany aging—progressive accumulation of beta-amyloid plaques and tau tangles, neuronal loss, and vascular wear—that create a higher probability of clinical dementia over time.

Other factors can influence risk. Family history and the ApoE4 genotype do elevate the likelihood and can affect when symptoms appear, but their overall impact is smaller than the effect of aging. Head trauma has been linked to some increased risk in certain studies, yet it does not predict risk as strongly as simply getting older.