Monitor on Psychology - December 2011 - (Page 52)

have protective effects on the brain. There are psychological explanations, too. Exercise may boost a depressed person’s outlook by helping him return to meaningful activity and providing a sense of accomplishment. Then there’s the fact that a person’s responsiveness to stress is moderated by activity. “Exercise may be a way of biologically toughening up the brain so stress has less of a central impact,” Otto says. It’s likely that multiple factors are at play. “Exercise has such broad effects that my guess is that there are going to be multiple mechanisms at multiple levels,” Smits says. So far, little work has been done to unravel those mechanisms. Michael Lehmann, PhD, a research fellow at the National Institute of Mental Health, is taking a stab at the problem by studying mice — animals that, like humans, are vulnerable to social stress. Lehmann and his colleagues subjected some of their animals to “social defeat” by pairing small, submissive mice with larger, more aggressive mice. The alpha mice regularly tried to intimidate the submissive rodents through the clear partition that separated them. And when the partition was removed for a few minutes each day, the bully mice had to be restrained from harming the submissive mice. After two weeks of regular social defeat, the smaller mice explored less, hid in the shadows, and otherwise exhibited symptoms of depression and anxiety. One group of mice, however, proved resilient to the stress. For three weeks before the social defeat treatment, all of the mice were subjected to two dramatically different living conditions. Some were confined to spartan cages, while others were treated to enriched environments with running wheels and tubes to explore. Unlike the mice in the bare-bones cages, bullied mice that had been housed in enriched environments showed no signs of rodent depression or anxiety after social defeat (Journal of Neuroscience, 2011). “Exercise and mental enrichment are buffering how the brain is going to respond to future stressors,” Lehmann says. Lehmann can’t say how much of the effect was due to exercise and how much stemmed from other aspects of the stimulating environment. But the mice ran a lot — close to 10 kilometers a night. And other experiments hint that running may be the most integral part of the enriched environment, he says. Looking deeper, Lehmann and his colleagues examined the mice’s brains. In the stimulated mice, they found evidence of increased activity in a region called the infralimbic cortex, part of the brain’s emotional processing circuit. Bullied mice that had been housed in spartan conditions had much less activity in that region. The infralimbic cortex appears to be a crucial component of the exercise effect. When Lehmann surgically cut off the region from the rest of the brain, the protective effects of exercise disappeared. Without a functioning infralimbic cortex, the environmentally enriched mice showed brain patterns and 52 behavior similar to those of the mice who had been living in barebones cages. Humans don’t have an infralimbic cortex, but we do have a homologous region, known as cingulate area 25 or Brodmann area 25. And in fact, this region has been previously implicated in depression. Helen Mayberg, MD, a neurologist at Emory University, and colleagues successfully alleviated depression in several treatment-resistant patients by using deep-brain stimulation to send steady, low-voltage current into their area 25 regions (Neuron, 2005). Lehmann’s studies hint that exercise may ease depression by acting on this same bit of brain. Getting the payoff Of all the questions that remain to be answered, perhaps the most perplexing is this: If exercise makes us feel so good, why is it so hard to do it? According to the Centers for Disease Control and Prevention, in 2008 (the most recent year for which data are available), some 25 percent of the U.S. population reported zero leisure-time physical activity. Starting out too hard in a new exercise program may be one of the reasons people disdain physical activity. When people exercise above their respiratory threshold — that is, above the point when it gets hard to talk — they postpone exercise’s immediate mood boost by about 30 minutes, Otto says. For novices, that delay could turn them off of the treadmill for good. Given that, he recommends that workout neophytes start slowly, with a moderate exercise plan. Otto also blames an emphasis on the physical effects of exercise for our national apathy to activity. Physicians frequently tell patients to work out to lose weight, lower cholesterol or prevent diabetes. Unfortunately, it takes months before any physical results of your hard work in the gym are apparent. “Attending to the outcomes of fitness is a recipe for failure,” he says. The exercise mood boost, on the other hand, offers nearinstant gratification. Therapists would do well to encourage their patients to tune into their mental state after exercise, Otto says — especially when they’re feeling down. “Many people skip the workout at the very time it has the greatest payoff. That prevents you from noticing just how much better you feel when you exercise,” he says. “Failing to exercise when you feel bad is like explicitly not taking an aspirin when your head hurts. That’s the time you get the payoff.” It may take a longer course of exercise to alleviate mood disorders such as anxiety or depression, Smits adds. But the immediate effects are tangible — and psychologists are in a unique position to help people get moving. “We’re experts in behavior change,” he says. “We can help people become motivated to exercise.” n Kirsten Weir is a writer in Minneapolis. Monitor on psychology • DeceMber 2011

Table of Contents for the Digital Edition of Monitor on Psychology - December 2011

Monitor on Psychology - December 2011
Letters
President’s Column
Contents
From the CEO
Willpower Pioneer Wins $100,000 Grawemeyer Prize
Single-Sex Schooling Called Into Question by Prominent Researchers
Maternal Depression Stunts Childhood Growth, Research Suggests
For Boys, Sharing May Seem Like a Waste of Time
Good News for Postdoc Applicants
In Brief
Treatment Guideline Development Now Under Way
Government Relations Update
Psychologist Named Va Mental Health Chief
The Limits of Eyewitness Testimony
Judicial Notebook
Random Sample
Time Capsule
Deconstructing Suicide
Questionnaire
A Focus on Interdisciplinarity
A Time of ‘Enormous Change’
The Science Behind Team Science
Good Science Requires Good Conflict
A New Paradigm of Care
Speaking of Education
Science Directions
New Labels, New Attitudes?
Psychologist Profile
Early Career Psychology
Unintended Consequences
Better Options for Troubled Teens
Saving Lives, One Organ at a Time
New Journal Editors
APA News
Division Spotlight
Guidelines for the Conduct of President-Elect Nominations and Elections
American Psychological Foundation
Personalities

Monitor on Psychology - December 2011