Introduction

Depression is one of the most common illnesses in the United States. Approximately 21 million people are affected by depression each year and it is one of the leading causes of disability for individuals between the ages of 15 and 44 (CDC).

Researchers believe that depression is a result of an imbalance of naturally occurring chemicals (neurotransmitters) produced in our bodies called serotonin and norepinephrine (Meyers, 2000). These neurotransmitters, also known as “chemical messengers,” help nerve cells communicate with one another by sending and receiving messages. These messengers are believed to regulate individuals’ overall mood and pain receptors. Vaidya & Duman (2001) further explain that the regulation of intracellular messenger cascades exerts a powerful control on almost all aspects of neuronal function, inclusive of neuronal morphology, gene expression, activity, and survival. Those who experience depression are believed to have a low supply of chemical messengers, thus resulting in depressive symptoms. Meyers (2000) states that the synthesis of most neurotransmitters is controlled within the brain. For some neurotransmitters, the amount of biochemical precursors present in the brain can influence their rate of synthesis.

Depression is also a common secondary condition. It is often times a comorbidity of other chronic illnesses and diseases such as diabetes, heart disease, obesity, spinal cord injuries, multiple sclerosis, stroke, Parkinson's disease, and arthritis. Depression can also worsen or exacerbate an individual’s current condition.

Depression Facts

* This information was retrieved from the National Institute of Mental Health at http://www.nimh.nih.gov/health/topics/depression/index.shtml

There are two main forms of depression, major depressive disorder and dysthymic disorder.

Major depressive disorder, also called major depression, is characterized by a combination of symptoms that interfere with a person's ability to work, sleep, study, eat, and enjoy once-pleasurable activities. Major depression is disabling and prevents a person from functioning normally. An episode of major depression may occur only once in a person's lifetime, but more often, it recurs throughout a person's life.

Dysthymic disorder, also called dysthymia, is characterized by long-term (two years or longer) but less severe symptoms that may not disable a person but can prevent one from functioning normally or feeling well. People with dysthymia may also experience one or more episodes of major depression during their lifetimes.

Psychotic depression occurs when a severe depressive illness is accompanied by some form of psychosis. Examples of this type of psychosis are hallucinations or delusions.

Postpartum depression is diagnosed if a new mother develops a major depressive episode within one month after delivery.

Seasonal affective disorder (SAD) is characterized by the onset of a depressive illness when there is less natural sunlight. This occurs during the winter months and generally lifts during spring and summer.

Bipolar disorder, also called manic-depressive illness, is not as common as major depression or dysthymia but is characterized by mood changes that cycle from extreme highs (e.g., mania) to extreme lows (e.g., depression).

Illnesses That Can Co-Exist with Depression

Depression also often co-exists with other serious medical illnesses such as heart disease, stroke, cancer, HIV/AIDS, diabetes, and Parkinson's disease. Studies have shown that people who have depression in addition to another serious medical illness tend to have more severe symptoms of both depression and the medical illness, more difficulty adapting to their medical condition, and more medical costs than those who do not have co-existing depression. Research has yielded increasing evidence that treating the depression can also help improve the outcome of treating the co-occurring illness.

Symptoms

People suffering from depression often experience emotional and physical symptoms. Emotional symptoms can include sadness, loss of interest in things you once enjoyed, feelings of guilt or worthlessness, restlessness, and trouble concentrating or making decisions. Physical symptoms can include fatigue, vague aches and pains, headaches, and changes in weight or sleep patterns. For some, depression can include thoughts of death or suicide.

Within the past decade, researchers have been working towards bridging the gap between mental health and exercise. They want to connect and use the psychological benefits from exercise to help treat disorders such as depression. Specific researchers such as Goodwin (2003), Fox (1999) and Dunn, Trivedi, Kampert, Clark, Chambliss (2005) are already focusing attention on the potential benefits that exercise could have on depression. Since depression is associated with several symptoms that affect people’s mood such as feelings of sadness, emptiness, fatigue, hopelessness, loss of interest in activities, and decreased energy, exercise would be thought to counteract those symptoms.

Treatment

Psychotherapy/counseling and medications (antidepressants) are the main treatment options for clinical/major depression. Most of the time, people go to counseling and take medications simultaneously. People need to be diagnosed before they can be provided with antidepressants; this can only be done through a medical doctor or a psychiatrist. Some examples of antidepressants that are on the market today are Cymbalta, Prozac, Zoloft, and Lexapro.

Side effects can vary from medication to medication. They include headache, nausea, dry mouth, constipation, and sexual problems. The most common side effects from antidepressants that may affect physical activity or exercise are drowsiness and blurred vision. These side effects usually only occur when individuals are first taking the medications, and often subside after a period of time. Be aware of any side effects that you may experience. Tailor your exercise(s) to account for possible drug side effects during your exercise routine (i.e., take proper safety precautions if experiencing blurred vision, such as only going for walks in familiar and low traffic areas).

Physical activity has been linked to contributing to overall improved physical health. Along with looking and feeling better, added psychological benefits may occur, such as improved life satisfaction and cognitive functioning. The “feeling good” or “high” experiences associated with exercise are sometimes what attract many people to it as well as participation in other fitness or physical activities.

Since depression is often associated with low energy and “feeling down,” exercise may be a great option to help with depression symptoms. As many people are aware, participation in exercise/physical activity increases individuals’ energy levels and helps with overall mood. When starting any kind of physical activity, individuals should start slow and gradually increase their intensity. Also, it is very important to set realistic goals, so that they are attainable. Otherwise, the chances of continuing the activity will be low and failure to reach that particular goal could exacerbate depression symptoms. Use of a support system to maintain the motivation to exercise is also important as depression can make it hard to get and stay motivated to exercise.

Summary of the Physical Activity Guidelines Advisory Committee Report Part G. Section 8: Mental Health (U.S. Department of Health and Human Services, 2008)

Is There an Association Between Physical Activity and Depression?
The Physical Activity Guidelines Committee reviewed several articles to establish if there’s an association between physical activity and various psychological disorders. This paper specifically focuses attention on depression. This particular section of the guidelines discusses whether physical activity can be used to prevent the onset of depression and/or reduce depressive symptoms; whether participation in physical activity impacts differently on individuals according to age, sex, race/ethnicity, or medical condition; and if the type, intensity, or timing of the physical activity changes anything.

Does Physical Activity Protect Against the Onset of Depression Disorders or Depression Symptoms?
The prospective cohort designs showed evidence that regular physical activity does protect against the onset of depression symptoms and major depressive disorder. As for bipolar disorder and other mood disorders, further research needs to be done in order to have more concrete evidence.

Does Physical Activity Reduce Symptoms of Depression?
With the exception of psychiatric disorders, evidence shows that participating in physical activity programs decreases depression symptoms in people diagnosed with depression as well as healthy adults.

Do the Effects of Physical Activity on Depression Symptoms Differ According to Age, Sex, Race/Ethnicity, or Medical Condition?
In general, the results indicate that regular physical activity decreases depressive symptoms regardless of age, sex, race/ethnicity, or medical condition. However, these factors do need to be further researched regarding their connection with depression and physical activity.

Do the Effects of Physical Activity Vary According to Features of Physical Activity, Including Type, or Timing (i.e., Session Duration, Weekly Frequency, and Length of Participation)?
Moderate to high levels of physical activity have been demonstrated to be more effective in reducing depression symptoms than low levels of physical activity. As far as the effects of minimal or optimal type or amount of exercise, further research is needed.

Research

A short literature review was performed in order to research the connection between depression and physical activity and to determine whether exercise/physical activities can be used to help treat depression. The following studies were selected to demonstrate possible benefits of using exercise to battle depression.

Study 1

Trivedi, M., Greer, T., Grannemann, B., Chambliss, H., & Jordan, A. (2006). Exercise as an augmentation strategy for treatment of major depression. Journal of Psychiatric Practice, 12, 4205-4213.

Purpose:
The purpose of the pilot test was to see if exercise could be used as an augmentation strategy in individuals with major depression.

Methodology:
In the pilot test, 17 patients diagnosed with major depression participated. The participants were already on antidepressants and their depression symptoms still existed. More specific criteria included the following: 1) 20 to 45 years of age, 2) primary diagnosis of unipolar, nonpsychotic major depressive disorder, 3) treatment with a selective serotonin reuptake inhibitor or venlafaxine for 6 or more weeks at a therapeutic dose, 4) Hamilton Rating Scale for Depression (17-item; HRSD17), and 5) physically inactive at time of study. The exercise intervention lasted 12 weeks and consisted of both supervised and home-based exercise sessions

Assessment tools used were the Structured Clinical Interview for DSM-IV Axis I Disorders—Clinician Version, the 17-item Hamilton Rating Scale for Depression, the 30-item Inventory of Depressive Symptomatology–Self-Report, and the General Activities form of the Quality of Life Employment and Satisfaction Scale (administered pre- and post-treatment)

Results:
Overall, results suggest the exercise program was an augmentation (increasing or adding to) strategy in treating patients with depression. Out of the 17 participants, 8 fully completed the entire 12-week program. Results based on the remaining participants still showed improvements in quality and life satisfaction. The data does help to support similar reports from previous works on how exercise could be very beneficial in treating depression along with antidepressant medications.

Discussion:
Preliminary findings suggest exercise augmentation strategies prove to be helpful in reducing depressive symptoms in patients. Exercise is linked to having great physical and mental health benefits. Since exercise does not interfere with antidepressant medications, researchers want to utilize its benefits in treating patients with depression. However, the preliminary findings warrant further research on utilizing both medications and exercise as an effective approach to treating major depression and with a larger sample size.

Study 2

Harris, A., Cronkite, R, and Moos, R. (2006). Physical activity, exercise coping, and depression in a 10-year cohort study of depressed patients. Journal of Affective Disorders, 93, 79-85.

Purpose:
To study the possible connection between physical activity, exercise coping, and depression on participants diagnosed with depression during the span of 10 years.

Participants:
This longitudinal study consisted of 424 participants who were receiving treatment for depression. Researchers recruited participants from five treatment centers: two community mental health centers, a health maintenance organization, a university hospital, and a Department of Veteran Affairs Medical Center. Participants were over the age of 18 and only diagnosed with unipolar depression.

Method:
Measurements were obtained using the Health and Daily Living Form (HDL), a survey of social, psychological, and physical functioning; Research Diagnostic Criteria (RDC), measuring for unipolar depression; the Physical Activity Index (PA), asking specific participation; and lastly the Exercise Coping (EC) to assess if they exercised more to cope with an important problem or stressful event they had faced in the previous year.

Information from measures of physical activity, exercise coping, depression and other information were taken in four intervals, baseline, 1 year, 4 years, and 10 years. Researchers also used multilevel modeling to project and predict individuals’ depression courses during the longitudinal study.

Results:
Ninety percent retention rate was achieved at the end of the study. During the 10 years, data showed that the more physical activity incorporated, the less the depression existed, even when age, medical problems and or presence of negative life events were assumed. As the result of increased physical activity, it invalidated the effects of medical conditions and negative life events on depression. Overall, the results show the potential benefits to use physical activity to help concurrently with medication in depression.

Discussion:
It seems that depression is reduced when there is an increase in physical activity. The study also suggests the benefits of including physical activity to help individuals who are dealing with depression, major life stressors, and other medical problems.

Conclusions

With depression being such a widespread and costly healthcare issue in America, and traditional treatments such as antidepressants and psychotherapy being time consuming, costly, often ineffective, and potentially creating unpleasant side effects or social stigmas, exercise may offer an affordable, available, and healthy part of a treatment plan. Although some research is conflicting and there is a definite need for more methodologically sound studies, overall, there are definite strides towards researching exercise and physical activity as a potential treatment option for clinical depression. Current research does not seem to allow or promote exercise treatment to be used as an independent treatment option. However, the data from the published studies seem very promising in that exercise/physical activity could be very beneficial in helping to treat clinical depression when paired with other treatments. It also seems as if the effects of exercise on the treatment does not have adverse effects, so though the extent and pathway for benefits is not known, research is definitely needed that provides more insight into the relationship between exercise and depression.

References

Centers for Disease Control and Prevention. (n.d.). 2008 National Center for Health Statistics. Depression in the United States Household Population, 2005-2006. Retrieved January14, 2009, from http://www.cdc.gov/nchs/data/databriefs/db07.htm

Dunn, A. L., Trivedi, M. H., Kampert, J. B., Clark, C. G., & Chambliss, H. O. (2005). Exercise treatment for depression – efficacy and dose response. American Journal of Preventative Medicine, 28, 1-8.

Fox, K. R. (1999). The influence of physical activity on mental well-being. Public Health Nutrition, 2, 411-418.

Goodwin, R. D. (2005). Association between physical activity and mental disorders among adults in the United States. Preventative Medicine, 36, 698-703.

Harris, A., Cronkite, R., & Moos, R. (2006). Physical activity, exercise coping, and depression in a 10-year cohort study of depressed patients. Journal of Affective Disorders, 93, 79-85.

Meyers, S. (2000). Use of Neurotransmitter Precursors for Treatment of Depression. Alternative Medicine Review, 5, 64-71.

National Institute of Mental Health - Health and Outreach. (n.d.). Depression. Retrieved January 20, 2009, from http://www.nimh.nih.gov/health/publications/depression

Trivedi, M., Greer, T., Grannemann, B., Chambliss, H., & Jordan, A. (2006). Exercise as an augmentation strategy for treatment of major depression. Journal of Psychiatric Practice, 12, 4205-4213.

U. S. Department of Health and Human Services. (2008). Physical Activity Guidelines Advisory Committee Report Part G. Section 8: Mental Health. Retrieved February 23, 2009, from http://www.health.gov/paguidelines/Report/G8_mentalhealth.aspx

Vaidya, V. and Duman, R. (2001). Depression – emerging insights from neurobiology. British Medical Bulletin, 57, 61-79.

This fact sheet was last updated on 05-06-2009.

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