Exercise as a Treatment for Depression

There is an illness that affects over one-third of American population (more than 19 million people) each year. Fifteen percent of its victims will commit suicide, yet 80% of its victims do not seek help despite the fact that this illness is treatable. If left untreated, this illness will be the second largest killer after heart disease by 2020, and has been shown in studies to contribute to fatal coronary disease (NIMH, 1999). The illness is depression, and it is a growing concern in America. Many treatments have been utilized to combat depression, including medications and psychotherapy, but there is much debate about whether these methods actually work, and what exactly about them changes mood. More recently, exercise has been studied as a treatment for depression, and the findings have been optimistic.

Defined as “a disorder of the brain and body’s ability to biologically create and balance a normal range of thoughts, emotions, and energy” (NIMH, 1999), depression is caused by unusual levels of chemicals, such as the neurotransmitters beta-endorphin, serotonin, and dopamine. Depression can vary in terms of severity. The exogenous “normal” depressed mood is the least serious level, since it is usually a reaction to a disturbing event, and more than likely the sufferer will recover on his or her own. Dysthymia is the next level, and is a mild endogenous depression with symptoms including chronic depressed moods and low self-esteem. Usually the sufferer is dealing with adjustment disorders and is less likely to recover without treatment. Major depressive disorder is characterized by despair and hopelessness, the inability to get out of bed, unusual appetite, and sometimes contemplation of suicide (NIMH, 1999). Manic depression is characterized by bouts of depression followed by bursts of excessive energy.

Due to the varying levels and types of depression, there are a variety of remedies available to provide customized treatment for each type of depression. The two most common treatments for depression are medication and counseling. Antidepressants have been around since the 1950’s and boast that they can raise one’s mood 60% to 80% when used properly (http://www.depression.com). However, Kirsch and Sapirstein found in a study done on Prozac, a popular antidepressant, that “approximately one quarter of the drug response is due to the administration of an active medication, one half is a placebo effect, and the remaining quarter is due to other nonspecific factors” (1998). In one recent trial, which compared the effectiveness of the herb St. John’s wort to that of Zoloft, St. John’s wort alleviated depression in 24 percent of study participants, compared with 25 percent for Zoloft. However, the placebo reportedly cured depression in 32 percent of participants (Mercola, 2002). Findings like these indicate that the effects of prescription drugs on depression may be overestimated, and largely due to the placebo effect. According to a study conducted by the National Institute of Mental Health, 55% of subjects suffering from depression reported a notable improvement in mood after 16 weeks of psychotherapy (1999). Cognitive behavior therapy is a relatively new approach where the therapist works directly with the patient to identify where his or her thought process differs from normal, and find ways to reduce the amount of negative thoughts. Studies done on therapy indicate that cognitive behavior therapy is more effective in treating depression than medications alone, but a combination of the two are ideal (Blackburn et al., 1981).

More recently, exercise has become a new alternative to more traditional methods of treating depression. The most basic reasoning behind this idea is that exercise has positive effects on one’s mind and body. For most people, losing weight or improving their physical appearance is a form of winning or success. Winning at anything improves mood, releases hormones like endorphins and reinforces additional successful behaviors. Exercise increases self-confidence, and produces a feeling of mastery and accomplishment. In a meta-analysis of 51 studies, Spence finds that an increase in self-esteem is linked to a decrease in depression (Spence et al., 1998). Participating in group exercise allows a person suffering from depression to engage in a more social atmosphere, which can have a therapeutic effect. In addition to its emotional and social effects, exercise also is shown to have a biological effect on lowering depression. The main cause of depression is unusual levels of neurotransmitters, including beta-endorphins and serotonin. Beta-endorphins are part of the mood regulating chemicals in the brain that can lower the feeling of pain and even induce a state of euphoria similar to the state known as “runner’s high.” Serotonin is responsible for the availability of neurotransmitters at receptor sites; therefore, there must be a balanced level of serotonin to maintain a stabilized mood (Moore, 1982). Several theories have been developed that attempt to explain how physical activity affects mood. The monoamine hypothesis, as explained by Ransford in 1982, describes how exercise increases the brain’s eminergic synaptic transmission, which directly affects mood. The endorphin hypothesis has been proven in its theory that extended exercise increases the release of endorphins, but little scientific evidence has been discovered to correlate this increase with mood (Moore, 1982). In fact, one study compared elite runners with meditators in terms of mood and the levels of circulating beta-endorphin and corticotropin-releasing hormone (CRH) following their respective exercises. Mood and CRH were elevated after both exercises, but only the runners experienced an increase in beta-endorphin, which suggests that it is not required for mood elevation (Wankel, 1993). Comparatively little research has been done to date on the exact effects of exercise to raise levels of these neurotransmitters, but scientists are hypothesizing that biologically, exercise may raise them enough to be considered a less expensive, yet beneficial alternative to medications and therapy.

Most of the research to date has studied the psychological effect of exercise on depression. According to Freemont & Craighead (1987), there are three basic theories that explain the relationship between exercise and depression. The first is the distraction hypothesis, which is based on the idea that anything that diverts a person’s attention from painful stimuli will lead to an improved mood after exercising. Russell et al. (2003) did a study to determine whether exercisers subjected to a distraction during exercise would report greater post-exercise mood improvement compared to exercisers without the distraction, and found that there was no significant difference between the experiment and control groups. However, Berger and Motl (2000), in their description of the distraction hypothesis, indicated that personal enjoyment of the activity is an important criterion, and the distractions in the above study may not have been enjoyable. A more successful demonstration of this theory would be Bahrke’s and Morgan’s experiment in 1978 where distractions from daily stressors were decreased through exercise. The second theory, the self-efficiency theory, is based on the idea that one must have the confidence that he or she can perform a certain behavior. The third theory, the mastery hypothesis, suggests that depression an individual is experiencing will decrease as that person uses exercise as a means of taking control. The activity training hypothesis suggests that participation in a variety of enjoyable activities exposes the individual to positive reinforcers that increase positive cognitions and enhance mood (Lewisohn, 1974).

Whether these theories apply or not, the majority of studies done on the psychological benefits of exercise as a treatment for depression conclude that it does indeed have a positive effect. The questions that remain are what type of exercise to do, how much exercise is needed to produce a favorable response, and at what level of intensity. Studies show that equally positive benefits can be obtained through aerobic activity, strength, or flexibility training. In a trial by Doyle et al. (1987), 40 depressed women were randomly assigned to one of the following exercise programs for eight weeks: running, weight-lifting, or a waiting list. Members of both exercise groups were less depressed by the end of the 8 weeks than the control group, and there was no difference in results in terms of the amount by which the depression was reduced. Research indicates that significant improvements can be achieved after as little as 5 weeks of aerobic or nonaerobic exercise of low to moderate intensity (50% of maximum heart rate) lasting 20-60 minutes per thrice-weekly session. Additionally, these improvements can be maintained for up to a year after, especially if some level of activity is maintained (Doyne et al., 1987). According to Artal (1998), when prescribing exercise as a treatment for depression, one must anticipate barriers, such as lack of energy and feelings of hopelessness and worthlessness, that are common in depression sufferers. The plan must be feasible and expectations should be realistic and attainable. The activity should be pleasurable, with specific goals stated. Compliance should be the ultimate goal, not intensity or time. In fact, a study on healthy female swimmers found that their levels of depression actually increased when their coach drastically raised the intensity of their routine (O’Connor, Morgan, Raglin, et al., 1989). Another important concern is whether the patient is being treated concurrently with medication, since some of the older medications contain side effects like orthostatic hypertension and sedation that may conflict with the patient’s ability to perform aerobic exercises.

Although more research obviously needs to be done on exactly which aspect of exercise enhances mood and lowers depression, there is no doubt that a correlation exists between the two. In a study published in the British Journal of Sports Medicine, the therapeutic benefits of aerobic exercise were seen after 10 days, as opposed to the 2-6 weeks it takes for the average antidepressant drugs to have an effect (2001). Using exercise as a treatment for depression may be more beneficial due to its low cost (compared to prescribed medications and therapy sessions) and the numerous side effects it can produce, including increased self-esteem, a more pleasing physical appearance, a feeling of mastery and control, and many others. If 41% of depressed women are too embarrassed to seek help, then an exercise program may be the key to alleviating the depression while maintaining their privacy (NIMH, 1999).









References
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