Mrs. S, age 44, is on leave from her job as a bank cashier because depressive symptoms interfered with her performance. At a university-based psychiatric clinic she reports feeling depressed, reduced interest in daily activities, problems with sleep onset and maintenance, inconsistent appetite, low energy, hopelessness, and decreased memory and concentration.
The resident psychiatrist diagnoses major depressive disorder (MDD) and starts Mrs. S on sertraline, 50 mg/d. The dosage is gradually titrated to 200 mg/d, and after 8 weeks she reports substantial improvement.
Mrs. S returns to her job but experiences residual low energy, lethargy, and inconsistent sleep. Her work schedule and caring for her 2 children at home prevent her from continuing weekly cognitive-behavioral therapy (CBT), but she soon notices that she feels more energetic. She reports that because of high gasoline prices she has been walking several miles daily to commute by train to work. The resident psychiatrist sees this as an opportunity to reinforce the benefits of exercise for depression.
Antidepressants alone do not adequately treat many patients with depression. In the STAR*D Project—which compared long-term outcomes of various depression treatments—only 28% to 33% of outpatients achieved remission with selective serotonin reuptake inhibitor (SSRI) monotherapy. Rates were somewhat higher with bupropion or serotonin norepinephrine reuptake inhibitor (SNRI) monotherapy, but greater benefit was obtained from augmenting SSRIs.1
Combining antidepressants with psychotherapy2 and lifestyle changes—particularly exercise—makes sense intuitively and is supported by well-designed studies:
- The 60% of adults in the National Comorbidity Survey who said they exercised regularly reported lower rates of depression and anxiety, compared with less active adults.3
- A meta-analysis of 11 randomized, controlled trials supports the use of exercise as an effective intervention for clinical depression.4
How does exercise affect mood? Possible mechanisms
Elevation of endorphins in the CNS
Changes in neurotransmitters such as serotonin and norepinephrine
Increased levels of brain-derived neurotrophic factor
Reduction of serum cortisol
Elevation of body temperature
Improved self-esteem
Distraction from daily stress
Induction of a relaxed state via biofeedback
This article examines the evidence supporting exercise for treating and preventing clinical depression. We begin by addressing clinicians’ concerns about motivating depressed patients to exercise.
Overcoming barriers
Physician issues. Busy physicians often omit discussions about exercise during brief office visits. Only 34% of 9,299 patients in a population-based survey5 reported that their doctors counseled them about exercise during their most recent visits. Counseling patients does not have to be time-intensive, however. A study of the Physician-based Assessment and Counseling for Exercise (PACE) project showed that 70% of physicians could provide exercise counseling in 3 to 5 minutes, and most patients reported following their physicians’ advice.6
Highly depressed individuals are at risk to quit when they encounter barriers to exercise and to respond to difficulties with frustration and self-disappointment. Thus, depressed patients may need support and encouragement to initiate and maintain regular exercise routines.7 Set small, realistic goals for them, and discuss how to solve problems and remove barriers to increase their likelihood to exercise.
Interventions are most likely to be effective when you counsel patients about exercise as prescription and discuss exercise at each visit.8 Previously sedentary patients have shown short-term moderate increases in physical activity in response to physician counseling. In a study of 212 adults (mean age 39, 84% female), the PACE project significantly increased minutes of weekly walking.9 More than one-half (52%) of patients increased their physical activity, compared with 12% of controls whose physicians did not provide the PACE intervention.
Patient issues. Lack of time and no appropriate space to exercise are common complaints, particularly among residents of regions with long, cold winters. Some patients perceive regular exercise as monotonous or boring, and others may lack the necessary initiative because of poor physical health, fear, negative experiences, or lack of knowledge about exercising. These barriers can be pronounced in older depressed persons. In a cross-sectional study of 645 residents of Jyväskylä, Finland, those age >75 with depressive symptoms were more than twice as likely to be physically inactive as nondepressed residents.10
An intensive exercise program is not the optimal starting point for many patients. Even walking or light jogging can be an effective exercise for depressed individuals with physical limitations. For these patients, a consultation with their primary physician may be necessary if a more intensive program has to be recommended.
Exercise as monotherapy
A dose-response relationship? Various mechanisms have been suggested for the benefits of exercise in depression (Box 1). Exercise alone—without medication—may be an effective treatment for mild and in some cases moderate MDD, and aerobic exercise may reduce depressive symptoms in a dose-response relationship.11