Alzheimer's Risk FactorsRisk factors for Alzheimer's disease increase the likelihood that an individual will develop the disorder but are not believed to directly cause it. The distinction between risk factors and cause is sometimes unclear because the biology of the disease is not fully understood. Risk factors for Alzheimer's include:
- older age
- being female
- genetic predisposition
- the presence of a specific form (ε4) of the gene that makes a protein called apolipoprotein E (APOE)
- elevated levels of lipoprotein(a) (a type of very-low-density cholesterol)
- cardiovascular disorders (such as high blood pressure, high cholesterol, and heart attack)
- Down syndrome
Head injury and depression are other possible risk factors for Alzheimer's.
Age, Gender & Alzheimer's Risk
Older age is the strongest risk factor for Alzheimer's disease. The likelihood of developing the disease doubles every five years beginning at age 65. After age 90, the risk reaches 30 to 50%. Some evidence suggests that the number of new cases begins to drop off after age 90, though other research shows that it may increase. This is an important issue to resolve, since a risk that continues to rise without leveling off would suggest that it is an inherent aspect of aging.
Most researchers now agree that women are at higher risk for developing Alzheimer's disease than men are, even when their longer lifespans are taken into account. It is not clear exactly why women are more vulnerable to the disease. Researchers are studying whether decreased levels of estrogen after menopause are responsible.