Why Does Education Reduce Risk for Alzheimer’s?

One of the earliest and most consistent findings in the extensive research base on risk factors of Alzheimer’s is the observation that those with higher education levels are less likely to be diagnosed with Alzheimer’s disease. Why would education protect against Alzheimer’s? If Alzheimer’s is a disease of the brain, why would people with more education be less likely to get it?

As it turns out, there are two major explanations, and both may be partly right.

The first and most common explanation is based on an idea called cognitive reserve. The idea behind this is that Alzheimer’s is diagnosed when someone has clearly developed memory problems as well as problems in some other areas of mental or personal functioning. People with higher levels of education probably function at somewhat higher levels in memory and other cognitive domains. The distance between where they start and the point at which they have recognizable decline is greater than for people whose baseline isn’t quite as high. When their functioning declines, it takes longer for them to reach the point where doctors will say they have Alzheimer’s.

The second explanation is, I think, more interesting because it gives us a direction to go in trying to prevent Alzheimer’s disease and maybe cognitive decline more generally. People with higher levels of education may also be more intellectually active as they get older. We know that what kinds of things people do on an everyday basis is related to how likely it is that they’ll get Alzheimer’s. People who have active social lives and spend time doing intellectually challenging things are less likely to get Alzheimer’s. And people with higher levels of education may do more of these things.

This raises the question of which comes first. Is that people with more education do things that make it less likely that they’ll get Alzheimer’s, or is that people who are less likely to get Alzheimer’s like to do intellectually stimulating activities. Since most of the research is done in a way that won’t less us decide which causes which, this question is still not answered completely. We do know, however, that certain kinds of mentally stimulating activities (as well as improved physical fitness) make changes in the brain. These changes in the brain are the kind of things that should improve people’s abilities, and decrease their chances for developing Alzheimer’s disease.

Does this mean that if you don’t have a high school diploma, a college degree, or a graduate education that you’re doomed to get Alzheimer’s? Nope. If you look closely at almost any of the risk factor studies, the actual change in risk for Alzheimer’s disease is fairly small, even if it’s statistically significant. It does mean that if you’re looking to do something to reduce your risk of Alzheimer’s, following a brain fitness program might be able to reduce your chances of getting memory or other cognitive problems.

Exercise, Physical Activity, and Brain Fitness

No matter what you believe about computer-based cognitive training and what it can do for you (see previous post), it’s pretty clear that computer training isn’t the only answer to the question of how to keep your brain fit as you get older. Exercise and physical activity are pretty clearly related to cognitive function in people over 50. There are even some prospective studies that show that increasing physical activity can improve your mental abilities.

A recent update to a systematic review in the Cochrane Database of Systematic Reviews once again confirms this (Angevaren, M., et al., Physical activity and enhanced fitness to improve cognitive function in older people. The Cochrane Database of Systematic Reviews, 1, 2008). Animal studies have shown that exercise has multiple physical effects on basic biological processes that can improve memory and cognition. Improved aerobic fitness (being able to do things like walking, running, or swimming) increases blood flow to the brain as well as the body’s ability to get oxygen from the blood. Exercise also activates substances called growth factors in the body. These factors causes cells to grow, and may increase the number of blood vessels in the brain. Human research shows that similar mechanisms may be at work in older adults.

Several meta-analyses (special studies that look at the results of multiple studies all at once) have shown a relation of physical activity of mental abilities including memory. Although many of these studies are correlational (this means that they show us which factor causes the improvement), there are also some prospective studies of exercise in older adults. These have shown that people who improve their physical fitness also improve their mental fitness. Brain fitness is more than computer-based training.