2. Depression

What is Depression?

It is relatively common to experience transient feelings of sadness or depressed mood. During these states, normal activities of daily living can feel arduous and require more effort than usual. Individuals with a depression disorder deal with this feeling for prolonged periods of time. For an individual to be diagnosed with depression, they must experience symptoms for two weeks or greater.

Depression is one of the leading causes of disability worldwide. An estimated 17.3 million adults in the United States had at least one major depressive episode in the past 12 months, and 21% of females and 13% of males ages 15-54 will have a major depressive episode at some point in their lifetime.  Depression is often comorbid with other mental health disorders such as anxiety disorders.

Risk Factors and Symptoms

Like anxiety disorders, depression disorders have both genetic and environmental factors. Individuals with a first-degree relative with depression have a 2 to 3 times higher risk of developing depression.  Other risk factors include:

• Female
• Younger than 50
• Less education
• Low income or unemployed
• Unmarried
• Parent psychopathology
• Childhood adversities/trauma
• Presence of other mental disorders

Depression is characterized by a wide range of symptoms including overwhelming feelings of sadness, either a loss of or excessive appetite, sleep problems, fatigue or loss of energy, impaired concentration or indecisiveness, lost interest in activities and decreased sexual drive. Symptoms generally occur more days than not and last for at least two weeks.

In the previous chapter, we briefly discussed areas in the brain related to mental health. In this chapter, we will discuss the neurotransmitters related to depression. A neurotransmitter is a way in which areas in our brain communicate with other brain regions. As part of the communication, there must be a receptor for the neurotransmitter to bind. When considering neurotransmitters, the most discussed is serotonin.

Here is a basic overview of the function of neurotransmitters: https://www.youtube.com/watch?v=InNhDfDfl5c.

Exercise for Depression

Only approximately 30% of individuals with depression seek treatment. The benefits of exercise for depression are the most studied and well established. Regular physical activity is associated with a lower risk of developing depression and has been found to be an important part of treatment for those with depressive disorders. Exercise training studies show clinically meaningful reduction in depression symptoms, as marked by a 50% reduction in symptoms or remission. In randomized control trials comparing exercise to pharmacological treatment, exercise was as effective as the standard medication.

However, it is important to note medication can drastically improve depression symptoms and you and your doctor should determine what course of treatment is the most effective to treat your depression. An exercise regime in conjunction with medication treatment may help to offset some of the side effects of antidepressants (e.g., weight gain, and sleep issues). Medications generally take 6-8 weeks before there is an improvement in symptoms of depression. Exercise may help to improve other symptoms of depression acutely such as sleep, appetite, and energy. 

For a comprehensive overview of how exercise might change depressive symptoms see the following video: https://www.youtube.com/watch?v=Y4ULcyem8oA