Alzheimer’s disease is a slow-onset, progressive dementia produced by neurodegenerative changes. It usually occurs in the elderly, though there are some cases of earlier onset. In its initial stages the symptoms can be slowed by various drugs. The more residual function that remains the better the drug therapy is at extending cognitive function. However, drugs do not slow down or stop the underlying degeneration, and there is no cure.
Our knowledge of the underlying neurological damage done to the brain in Alzheimer’s disease suggests that most neurons destroyed are involved in learning and memory. True Alzheimer’s disease has a genetic component and can run in families. But the origin of some dementia is uncertain. It can be vascular—insufficient blood flow to allow oxygenation of the brain. There is also an old idea that has never been disproven, that the disease may be caused by a lenti-virus (a slow-acting virus). However, little is known of the factors that reduce the incidence of Alzheimer’s dementia.
It is known that people who exercise regularly and are on a Mediterranean type diet are at less risk for Alzheimer’s disease. In a study reported in JAMA, 1,880 New Yorkers in their early 70s were enrolled and followed. Their level of exercise and the quality of their diets were evaluated. Within five years, 282 members of this group had an Alzheimer’s disease diagnosis. Those with the best diets had a 40% less chance of being diagnosed with AD than those with the worst diets, while those who had the most exercise were 37% less likely to be diagnosed with AD than who exercised least. When the group was divided into the top 1/3 with best combined diet and exercise characteristics and compared with the bottom 1/3 of the group based on diet and exercise characteristics, the top 1/3 was 59% less likely to be diagnosed with AD. The combination results showed a magnified effect, presumably because each factor (diet and exercise) contributed something unique to the outcome.
In addition to the observations made in the JAMA New York study, we know that the level of education or level of brain work generally lessens both the incidence and severity of AD later in life.
