Ask the doctor: Can supplements prevent dementia?
Q. Is there any medication or over-the-counter supplement or vitamin I can take to prevent dementia?
A. Unfortunately, no drug, supplement, or vitamin can prevent you from getting dementia. The 2010 Consensus and State-of-the Science Statement on Preventing Alzheimer's Disease and Cognitive Decline from the National Institutes of Health reviewed all the available scientific evidence on the topic. The authors concluded, "Evidence is insufficient to support the use of pharmaceutical agents or dietary supplements to prevent cognitive decline or Alzheimer's disease." So there are currently no good scientific data to show that taking anything—whether it's ginkgo biloba, vitamin E, or donepezil (Aricept)—will protect you from losing mental function.
The authors did find evidence that physical and leisure activities (such as club membership, religious services, painting, or gardening) may ward off dementia, and a study in Annals of Internal Medicine found an association between higher levels of physical fitness in middle age and a lower risk of developing dementia after age 65. Although the findings don't prove that physical fitness prevents dementia, and they don't suggest a specific exercise "prescription" for dementia prevention, they do suggest that higher physical fitness levels in middle age may protect against mental loss later in life.