Most cases of Alzheimer's occur late in life, after age 65. Because the main drivers of the disease appear to be amyloid and tau deposits, which take time to build up, older people are more at risk of developing Alzheimer's.
- Family History
Genetic mutations that promote amyloid buildup in the brain are shared among family members and can be passed down from generation to generation.
More women than men tend to develop Alzheimer's, although it's not clear why. About 16% of women over 70 get the disease, while only 11% of men do. Experts suspect that changes in hormones following menopause may play a role, or that women may be lacking some protective factor that helps men to ward off amyloid plaque formation better.
- Cardiovascular Disease
While it might seem that a brain disorder has little to do with heart disease, damage to the heart and circulatory system that delivers blood to the brain can increase the risk of Alzheimer's. Up to a quarter of the blood pumped out from each heart beat is dedicated to the brain, and any deficit in that flow can boost the risk of nerve damage that can promote Alzheimer's.
- Brain Trauma
Injury to the brain, especially repeated blows or concussions can lead to nerve damage that contributes to Alzheimer's. According to some theories, weakened nerve cell connections due to brain injury may promote deposition of amyloid plaques.