College in retirement helps stave off mental decline

A new study from the University of Toronto helps explain why higher education appears to slow down cognitive decline as people age. It seems possible that education strengthens the ability to "call in the reserves" of mental prowess. Brain imaging in older adults taking memory tests showed that more years of education were associated with more active frontal lobes – the opposite happens in young adults. College seems to pay off well into retirement.

The report appears in the March issue of Neuropsychology, which is published by the American Psychological Association (APA).

Mellanie Springer, MSc and a team of psychologists, chose a memory task because even normal aging brings some memory loss. They were intrigued by how highly educated patients with Alzheimer's disease appear to be better able than less educated patients to compensate for brain pathology, which suggested that education somehow protects cognition.

The team studied the relationship between education and brain activity in two different age groups: 14 adults of ages 18 to 30, with 11 to 20 years of education, and 19 adults of age 65 and up, with eight to 21 years of education. Each participant went through a number of memory tests while their brains were being scanned with functional magnetic resonance imaging (MRI). The images produced showed which neural networks became active when participants tapped into memory. The psychologists then correlated brain activity for each member of the two groups with their corresponding years of education.

Relative to education, younger and older adults had opposite patterns of activity in the frontal lobes (behind the forehead) and medial temporal lobes (on the sides). In young adults performing the memory tasks, more education was associated with less use of the frontal lobes and more use of the temporal lobes. For the older adults doing the same tasks, more education was associated with less use of the temporal lobes and more use of the frontal lobes.

This suggests that older adults - especially the highly educated - use the frontal cortex as an alternative network to aid cognition.

Many studies have now shown that frontal activity is greater in older adults, compared to young; this study suggests that this effect is related to the educational level in the older participants. The higher the education, the more likely the older adult is to recruit frontal regions, resulting in a better memory performance, says co-author Cheryl Grady, PhD, Grady is assistant director of the Rotman Research Institute In Toronto and holds a Canada Research Chair in Neurocognitive Aging.

Education appears to enable older people to more effectively "call up the reserves".Older adults who are highly educated are possibly more able to enlist the frontal lobes into working as a type of cognitive reserve or alternative network. Grady cites evidence that when older adults tap their frontal lobes, that activity engages the medial temporal regions less than it does in younger adults. She speculates that "if the medial temporal lobes can't be recruited properly, the frontal lobes have to help out." Grady also thinks that the frontal lobes' compensatory role supports cognition generally.

The researchers hope in the future to understand how "mental exercise" strengthens "mental muscles", in old age. Animal brains respond to more complex environments by growing more neural connections; more education while the brain is still developing - up to age 30 it is still maturing - might cause more connections between brain regions to form. Although some of these are lost with age, there are still enough left, a type of redundancy in the system, says Grady.

Highly educated people keep more active physically and mentally as they age, which also has a beneficial effect on cognition.