Dec. 25, 2000 -- Claire Urmson began strength training several years
ago to recover from an accident. To her surprise, the improvement she felt went
far beyond her immediate physical problem. "I'm not somebody who loves
exercise," says Urmson, 66. "But I really love the way it makes me
Serotonin acts as a neurotransmitter, a type of chemical that helps relay signals from one area of the brain to another. Although serotonin is manufactured in the brain, where it performs its primary functions, some 90% of our serotonin supply is found in the digestive tract and in blood platelets.
Indeed, a recent Finnish study joins a growing body of research
in suggesting that exercise can have strong psychological benefits. Scientists
surveyed 663 people in Finland, ages 65 and older, in 1988 and again in 1996.
Over time, the intensity of physical exercise (defined in three categories:
doing necessary chores, walking regularly, and exercising strenuously, in order
of increasing difficulty) decreased with age, and this decrease was associated
with developing more symptoms of depression. The
researchers therefore concluded that a reduction in exercise increased the risk
of depression in older adults.
The study did have limitations. For instance, circumstances
that impeded exercise could in and of themselves be depressing, the researchers
said. But many experts believe that exercise has a direct impact on depression
-- and not just in older people.
"The findings are the same in elderly people as in younger
people: Exercise tends to lower depression" and anxiety, says Daniel
Landers, PhD, regent's professor in the department of exercise science and
physical education at Arizona State University.
Some scientists believe that exercise may increase the
concentrations in the bloodstream (and therefore the brain) of the
neurotransmitters serotonin and norepinephrine, as do certain antidepressant drugs. Indeed, in
a recent study of clinically depressed 50- to 77-year-olds at Duke University
Medical Center, researchers found that performing regular exercise compared
favorably in reducing depression over a 16-week period both with taking the
antidepressant Zoloft (a commonly prescribed serotonin reuptake inhibitor), and
with the combination of taking the drug and exercising.
Six months after the Duke study ended, the researchers
completed a second round of interviews with the subjects to find out how they
were faring. Remarkably, the scientists found that the subjects who were in the
exercise-only group were far less likely to relapse into a major depression than either the
group who had been on medication, or those who had combined medication with
The researchers speculated that people who attributed their
improved mental health to their own
personal efforts may have felt more empowered -- and thus were less likely to
relapse into depression than people who may have attributed their improvement
to taking a pill.
Now Duke is undertaking a new study to further examine the
issue. For instance, how much of the exercise-only group's benefit had to do
with the "social support" of getting together with other people to
exercise? The new study will include subjects who exercise at home, as well as
others who exercise in group settings.