Higher Levels of Education Do Not Protect Against Age-Related Memory Decline
In the current issue of the journal "Research on Aging" our article, ?Education and Cognitive Decline in Older Americans,? suggests that after age 70, adults with a high level of education may begin to lose the ability to retain words faster than their less-educated peers.
By Dawn Alley, Athan Bezaitis and Eileen Crimmins
These findings do not mean that education harms cognitive functioning later in life. In fact, most indicators show that higher levels of education are conducive to healthy aging. People with higher education have better physical and cognitive health at most ages; in old age the differences disappear. Our results provide new understanding of the way our cognitive ability changes with age and how this change differs by education. More specifically, not all aspects of cognitive performance later in life relate to education in the same way. Persons with higher education do better at all aspects of cognitive functioning at age 70 or the youngest age in our study: verbal memory, working memory, and mental status. Although individuals with higher levels of education had a higher ability at any given age, they actually experienced slightly greater absolute decline than those with less education in the more complex memory tasks. Those with the highest levels of education, who had for years been able to bank on their years of schooling to compensate for natural declines in cognitive function, were less able to do so after 70 years of age.
Data came from the Asset and Health Dynamics of the Oldest Old (AHEAD) study, a nationally representative longitudinal study of older Americans born in 1923 or earlier. This study is the first to investigate a relationship between education and the rate of cognitive decline within a nationally representative sample of older adults that accounts for the racial and educational heterogeneity of the older population in the United States.
Verbal memory was tested by immediate and delayed recall, which consisted of 10 common nouns read aloud by the interviewer, followed by a request for respondents to recall as many nouns as possible from the list. Five minutes later, participants were again asked how many of the words they could remember.
We expected to find that higher education would be linked to both better cognitive functioning and slower decline. Persons with more education may have denser development of neural networks and therefore better mental processing throughout their lives. It is also true that more schooling is linked to generally higher living standards, including better access to health care and better eating habits. All of these factors led us to expect that there would be slower decline in loss of cognitive skills with more education. However, one possible explanation for the faster decline we observed in adults with more schooling is that educated individuals may no longer be able to use strategies or memory aids they once relied on to help them remember things. For instance, people could write down more information or make efforts to link things in their minds that need to be remembered. For a while, these strategies may help people with more education compensate for age-related memory declines, but as they get older their brains may become overwhelmed and they may no longer successfully compensate using such strategies. After a certain age, education does not provide better protection from normal, age related memory decline.
While the relationship between higher education and memory loss is contrary to the expected relationship between higher education and the development of dementia, we find that those with higher education do better on mental-status tests that indicate dementia-like symptoms. So we still find persons with higher education are protected longer from conditions like dementia.
In interpreting our findsings, it is important to note that because the study did not follow people across the entire lifespan but started at age 70, there could be other unobserved factors that affected the results. For example, those with less education may start their cognitive decline before age 70, with faster earlier decline in the ages before our study began.
In spite of this limitation of the study, our findings shed new light on how the brain functions throughout the entire lifecycle. Education levels and mental aptitude of the older population are becoming of great interest, especially as the baby-boomers hit their 60s. This relatively well-educated segment of the population now make up one-third of the American population, and as this group with higher education gets older, the cognitive ability of older populations will improve.It is important to replicate these findings in other countries in order to clarify their generalizability. One study in Australia has reported somewhat similar findings.
Alley et al, Research on Aging 2007 29: 73-94