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Depression is a mood disorder. It is marked by a lasting low mood, sadness, and lack of interest in activities. It disrupts functioning. Bouts of depression can last for weeks, months, or years. Treatment often helps people recover.


The exact cause of depression is not known. It is likely due to environment, personal traits, and stress.

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Risk Factors

Depression is more common in women. Many things raise the risk. Examples are:

  • A personal or family history of depression
  • Long term illness
  • Childhood abuse, neglect, or trauma
  • Alcohol and drug abuse
  • Stress, loss, or major life changes
  • Other mental illnesses or brain injury
  • Partner abuse
  • Little or no social support


Depression can differ from person to person. Some have only a few symptoms, while others have many.

Symptoms can change over time. They may include:

  • Lasting sadness, anxiety, or emptiness
  • Loss of interest in hobbies, activities, or sex
  • Feeling helpless, hopeless, or guilty
  • Sleeping too much or too little
  • Feeling tired, restless, or irritable
  • Trouble with focus, memory, or decisions
  • Changes in eating or weight
  • Thoughts of death or suicide

Sometimes there are physical symptoms. Examples are aches and pains that cannot be explained.


The doctor will ask about your symptoms and health history. A physical exam may be done. The doctor may give mental health exams. Tests may be done to rule out other causes.


The goal is to ease symptoms and improve function. Treatment depends on the type and severity of depression. Severe depression may need hospital care. Care is urgent if someone might hurt themselves or others.

Options may be:

  • Medicines, such as:
    • Antidepressants
    • Mood stabilizers and antipsychotics—if needed
    • Sedatives for anxiety—usually short term
    • Ketamine as a nasal spray or IV—may be used if other options do not work
    • Other medicines
  • Counseling such as cognitive-behavior therapy and others—to improve coping
  • Lifestyle changes such as:
  • Supplements, such as St. John's wort and DHEA—may help some

Other treatments may be:

  • Light therapy—sitting near an ultra-bright light for a certain time each day
  • Sleep deprivation therapy—a short term option that may improve mood

Sometimes symptoms are severe and other treatments do not work. In this case, options may be:

  • Electroconvulsive therapy ECT—a brief electric pulse to the brain to help reset it
  • Vagus nerve stimulation (VNS)—an implanted device that may alter signals to the brain


To reduce the risk of depression:

  • If at risk, seek treatment.
  • Build strong friendships.
  • Eat healthy food, including fruits, vegetables, and whole grains.
  • Learn coping skills.
  • Get regular sleep, exercise, and fun.
  • Do not abuse alcohol or drugs.


Depression and Bipolar Support Alliance

Mental Health America

Canadian Resources

Canadian Mental Health Association

Canadian Psychiatric Association


Columbia University. Q&A on bright light therapy. Columbia University website. Available at: Accessed March 15, 2021.

Depression. Mental Health America website. Available at: March 15, 2021.

Depression. National Institute of Mental Health website. Available at: Accessed March 15, 2021.

Depression alternative treatments. EBSCO DynaMed website. Available at: Accessed March 15,

Kandola A, Ashdown-Franks G, et al. Physical activity and depression: Towards understanding the antidepressant mechanisms of physical activity. Neurosci Biobehav Rev. 2019;107:525-539.

Major depressive disorder (MDD). EBSCO DynaMed website. Available at: Accessed March 15, 2021.

St. John's wort. EBSCO Natural and Alternative Treatments website. Available at: Accessed Macrh 15, 2021.

St. John's wort and depression. National Center for Complementary and Integrative Health website. Available at: Accessed March 15, 2021.

St. John's wort for depression. EBSCO DynaMed website. Available at: . Accessed March 15, 2021.