Education, Cognitive Reserve and Alzheimer's

Summary: A recent study confirms that higher levels of education seem to delay cognitive decline, but may increase the rate of decline once it starts. The results of this study don’t mean much for any one person. But they do mean that memory loss might not be readily apparent in people with Alzheimer’s, especially those with more education. The findings point to the need to detect changes in the brain before the symptoms of Alzheimer’s and other dementias appear. This will be especially important when treatments to delay progression are available.

The title of a recent press release from the American Academy of Neurology (AAN) caught my eye – “Educated People Who Develop Dementia Lose Memory At A Faster Rate.” The press release was based on study results published in the October 23, 2007 issue of the AAN’s journal Neurology.

At first glance, this finding seems to contradict earlier studies that show lower education levels are associated with increased risk of Alzheimer’s or dementia. Is more education good or bad when it comes to dementia?

To clear up my confusion, I checked in with Charlie Hall, Ph.D., the lead author of the article behind the AAN’s press release. Dr. Hall is Associate Professor at Albert Einstein College of Medicine, in Bronx, New York. He works in the Division of Biostatistics, Department of Epidemiology and Population Health, where he and his colleagues have studied “successful aging” since 1980. Dr. Hall focuses on statistical methods for analyzing data from the department’s studies.

What The Study Showed About Dementia And Education Levels

This new study was set up to test the cognitive reserve hypothesis, which says that a person’s intelligence, education or experience may give him more capability (and maybe more neurons) to compensate for the brain degeneration seen with Alzheimer’s. The hypothesis stems from the observation during autopsies that some people with no apparent memory loss had a large amount of Alzheimer’s plaques. These people also had larger brains and more neurons than others their age.

Theoretically, people with cognitive reserve who develop Alzheimer’s are able to compensate for their memory loss, and are diagnosed later in the disease progression than people without that reserve. As the AAN press release title indicates, their progression might be seen as more rapid than those diagnosed at earlier stages, theoretically because they are diagnosed when the disease is further along,

Analyzing the data for 117 people who were part of the Bronx Aging Study, Dr. Hall and his colleagues found that “higher education delays the onset of accelerated cognitive decline” but that “once it begins it is more rapid in persons with more education.” In this group, each additional year of formal education delayed the time of accelerated decline (presumably when dementia would be diagnosed) by .21 years. The calculations for how much each year of education affected the rate of decline were more complicated, but significant. Dr. Hall believes that these findings support the cognitive reserve hypothesis.

Other studies have also shown a more rapid decline in people with more education. What do these studies mean for you?

Applying the Study Results to My Father’s Situation

“It is difficult with the current state of knowledge to apply this to any particular individual,” says Dr. Hall. But individual cases can be helpful to illustrate what the statistics mean. I asked him to look at my father’s case as an example.

I think I started noticing Dad’s memory problems when he was 68. What if he hadn’t had a four year degree, and had simply graduated from high school? Using the numbers from this new study, he might have developed noticeable memory problems about ten months earlier (4 years of education x .21 per year = .84 years or about 10 months).

Again using the numbers from the study, how much faster did he decline because of those extra four years of education? Dr. Hall calculates that four years of college might have meant that Dad declined 14 percent faster than if he had simply completed high school. Of course, this is all theoretical. Dad had good days and bad days, and I'm not sure that declining test scores captured what was really happening.

Why The Results Might Not Apply To You

You might be tempted to apply the results of this study to your own situation. Here are some reasons why this is a bad idea:

*“Individuals vary widely - an average finding may not be meaningful in your case.

*The median age of the participants when they first joined the study was 81. It’s unclear whether the findings would apply to a younger or older population.

*In the group of people studied, only 21 people had graduated from high school, and nine participants had three or fewer formal years of education. It’s unclear whether the findings would apply to a more educated population.

*If you have dementia, or develop it, your dementia may not be the same as the dementias of the study participants. This is a problem that many Alzheimer’s researchers struggle with. “Accurate subtyping of dementia is notoriously difficult even for an experienced neurologist,” says Dr. Hall, “and in our experience, many older persons with dementia have a mixed pathology.”

*The relationship between education and the theoretical cognitive reserve isn’t clear. “We can't say right now that the education CAUSES the reserve,” he cautions. “It is entirely possible that people with those characteristics [larger brains, more neurons, later onset of dementia] happen to be the people who get more education.”

The Need For Better Diagnostic Techniques For Alzheimer's And Other Dementias

Whether or not education levels and cognitive reserve prove to be important, these results support the urgent need for better diagnostic techniques for dementia.

“This study implies that for many, reliance on clinical symptoms will result in a too-late identification of the disease,” says Dr. Hall. “For clinicians, it is important to realize that early signs of dementia might not be obvious in persons with high education.” This was certainly true for my father – his family physician dismissed his complaints of memory problems for years.

“This research of course needs to be replicated in other studies,” Dr. Hall says. “And it should motivate more research towards biological markers of dementia, both vascular and Alzheimer's, because we will need them once we have treatments that change the course of the disease process in order to identify candidates for the treatment.”

Comments

[Carole Mulliken, DementiaUSA]

Dear Tangled Neuron:

Thank you so much for the clear and analytic section, "Why The Results Might Not Apply To You."

As a person with dementia, my abilities to observe the limitations of any study or to track the falacious logic are failing. It helps keep me sharp to read your assessments, and it prevents me from drawing conclusions about myself that might be inappropriate.

Carole