March 14, 2005 |
College seems to pay off well into retirement. A new study from the University of Toronto sheds light on why higher education seems to buffer people from cognitive declines as they age. Brain imaging showed that in older adults taking memory tests, more years of education were associated with more active frontal lobes — the opposite of what happened in young adults. It appears possible that education strengthens the ability to “call in the reserves” of mental prowess found in that part of the brain.
A full report appears in the March issue of Neuropsychology, which is published by the American Psychological Association (APA).
A team of psychologists led by Mellanie Springer, MSc, 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.
To understand the mechanism, the researchers 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. Springer and her colleagues ran each participant through several memory tests while scanning his or her brain with functional magnetic resonance imaging (MRI). The resulting images showed Springer and her colleagues 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.
The finding suggests that older adults — especially the highly educated — use the frontal cortex as an alternative network to aid cognition. Says co-author Cheryl Grady, PhD, “Many studies have now shown that frontal activity is greater in old adults, compared to young; our work 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.” 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.” Highly educated older adults might be better able to enlist the frontal lobes into working for them 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 further thinks that the frontal lobes’ compensatory role supports cognition generally.
Researchers hope to further understand how mental exercise strengthens mental muscles, so to speak, in old age. Animal brains respond to more complex environments by growing more neural connections; perhaps, says Grady, “more education while the brain is still developing — up to age 30 it is still maturing – causes more connections between brain regions to form. When some of these are lost with age, there are still enough left, a type of redundancy in the system.”
She adds that highly educated people keep more active physically and mentally as they age, which also has a beneficial effect on cognition.