Researchers investigating brain size
and mental ability say their work offers evidence that education protects the
mind from the brain’s physical deterioration.
It is known that
the brain shrinks as the body ages, but the effects on mental ability are
different from person to person. Interestingly, in a study of elderly men and
women, those who had more education actually had more brain shrinkage.
"That may seem like bad news," said study author Dr. Edward Coffey, a
professor of psychiatry and of neurology at Henry Ford Health System in Detroit.
However, he explained, the finding suggests that education allows people to
withstand more brain-tissue loss before their mental functioning begins to break
down.
The study, published in the July issue of Neurology, is
the first to provide biological evidence to support a concept called the
"reserve" hypothesis, according to the researchers. In recent years,
investigators have developed the idea that people who are more educated have
greater cognitive reserves to draw upon as the brain tissue to spare.
Examining brain scans of 320 healthy men and women aged 66 to 90,
researchers found that for each year of education the subjects had, there was
greater shrinkage of the outer layer of the brain known as the cortex. Yet on
tests of cognition and memory, all participants scored in the range indicating
normal.
"Everyone has some degree of brain shrinkage," Coffey
said. "People lose (on average) 2.5 percent adecade starting at
adulthood."
There is, however, a "remarkable range" of shrinkage
among people who show no signs of mental decline, Coffey noted. Overall health,
lie said, accounts for some differences in brain size. Alcohol or drug use, as
well as medical conditions such as diabetes and high blood pressure, contribute
to brain-tissue loss throughout adulthood.
In the absence of
such medical conditions, Coffey said, education level helps explain the range of
brain shrinkage exhibited among the mentally-fit elderly. The more-educated can
withstand greater loss.
Coffey and colleagues ganged shrinkage
of the cortex by measuring the cerebrospinal fluid surrounding the brain. The
greater the amount of fluid means the greater the cortical shrinkage.
Controlling the health factors that contribute to brain injury, the researchers
found that education was related to the severity of brain shrinkage. For each
year of education from first grade on, subjects had an average of 1.77
milliliters more cerebrospinal fluid around the brain.
For
example, Coffey’s team reported, among subjects of the same sex and similar age
and skull size, those with 16 years of education had 8 percent to 10 percent
more cerebrospinal fluid compared with those who had four years of
schooling.
Of course, achieving a particular education level is
not the definitive measure of someone’s mental capacity. And, said Coffey,
education can be "a proxy for many things". More-educated people, he noted, are
often less likely to have habits, such as smoking, which harm overall health.
But Coffey said that his team’s findings suggest that like the body, the brain
benefits from exercise. "The question is whether by continuing to exercise the
brain we can forestall the effects of (brain shrinkage) ," he said. "My hunch is
that we can."
According to Coffey, people should strive
throughout life to keep their brains alert by exposing themselves to new
experiences. Traveling is one way to stimulate the brain, he said; a less
adventuresome way is to do crossword puzzles.
"A hot topic down
the road," Coffey said, "will be whether education even late in life has a
protective effect against mental decline."
Just how education
might affect brain cells is unknown. In their report, the researchers speculated
that in people with more education, certain brain structures deeper than the
cortex may stay intact to compensate for cortical
shrinkage. |
