12 Surprising Facts About Depression

Depression is a complex medical illness that can impact the way you think, feel, and engage in daily activities. Here are some facts about depression that you may not know.

Medically Reviewed
illustration of rear view of woman looking into distance
Did you know that depression may increase your risk of diabetes, heart disease, and other health problems? That's just one of many facts that may surprise you.Marta Lebek/Stocksy

Depression is often misunderstood as just feeling sad. But it’s a complex medical condition thought to be caused by a combination of factors, including genetic, biological, psychological, and environmental triggers, according to the National Institute of Mental Health (NIMH). While it’s not yet clear exactly what causes depression, researchers have made great progress in learning more about how to manage and treat this common mental health disorder. Here are some facts about depression, depression symptoms, and depression management that might surprise you.

What Is Depression?

Doctors diagnose major depression (also called major depressive disorder) based on criteria in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, or DSM-V. A depression diagnosis is made when at least five of the following symptoms occur nearly every day for at least two weeks:

  • Depressed mood
  • Loss of pleasure in all or most activities
  • Significant weight change or change in appetite
  • Change in sleep
  • Change in activity
  • Fatigue or loss of energy
  • Diminished concentration
  • Feelings of guilt or worthlessness
  • Thoughts of suicide

To diagnose major depression, either depressed mood or loss of pleasure in activities must be one of the symptoms.

12 Things You Might Not Know About Depression

While the definition of major depression may seem simple enough, depression has profound and varying impacts. Here are some facts about depression that everyone may not know.

  1. Depression has different triggers. People have a higher risk of depression if they’ve recently been through a stressful life event; if they’ve had depression in the past; or if a close family member has been depressed. Sometimes depression develops without any obvious cause.
  2. Genes provide some (but not all) of the answers. The genetic predisposition to depression is becoming better understood and might explain why one person becomes depressed and another doesn’t, says Ole Thienhaus, MD, a professor of psychiatry at the University of Arizona College of Medicine in Tucson. A family history of depression matters, but it’s not always the only factor. For example, the heritability rate — the percentage of a trait that may be due to genes — of depression is only about 37 percent, according to a study published in July 2018 in the journal Frontiers in Psychiatry.
  3. Depression affects the body. Headache, stomach problems, headaches, and general aches and pains without a clear physical cause can all be symptoms of depression, according to the NIMH.
  4. Depression might be a “gut feeling.” A study published in August 2020 in the journal Cureus found a strong connection between gut health and mental well-being, noting that depression is strongly associated with gut imbalance. A varied diet including probiotics and prebiotics may play a role in managing depression, although more research is needed.
  5. Depressed brains may look different. Some people with major depressive disorder have changes in the brain that can be seen in imaging tests such as magnetic resonance imaging (MRI) scans, according to a review published in December 2019 in the journal Translational Psychiatry that evaluated studies examining the use of MRI scans to diagnose and treat major depressive disorder. (That said, the paper also notes that major depression is a biologically complex disorder that causes different changes in the brain in some people, and that MRI scans alone are not useful in the diagnosis of major depressive disorder; the researchers therefore state the importance of new imaging techniques and ways of analyzing that information to help diagnose depression.)
  6. Depression is linked to other health problems. People with depression are also at higher risk of chronic inflammatory or autoimmune conditions such as diabetes, heart disease, arthritis, or irritable bowel disease. It’s unclear if depression causes inflammation or vice versa, according to a study published in July 2019 in the journal Frontiers in Immunology.
  7. Depressed people might not look depressed. “Depression is a hidden illness,” says Jeremy Coplan, MD, a professor of psychiatry at the State University of New York (SUNY) Downstate Medical Center in Brooklyn. Some people can seem upbeat and cheerful, but inside they’re struggling with the symptoms of depression.
  8. Exercise can help manage depression. “Exercise improves mood state,” says Dr. Thienhaus, who explains that exercise helps stimulate natural compounds in the body that can make you feel better. Aim for at least 30 minutes of physical activity most days. “We typically recommend that people with depression exercise, develop a healthy diet, and go to bed at a regular time.” A study published in October 2017 in the American Journal of Psychiatry found that even one hour of physical activity each week was associated with a 12 percent lower incidence of depression.
  9. It’s common to need to try more than one antidepressant. Many people with depression don’t get relief from the first antidepressant they try. That is expected because for unknown reasons, different people benefit from different medications, and some don’t find any benefit from medications we currently have available. According to Diane Solomon, PhD, a psychiatric nurse practitioner in Portland, Oregon, people may sometimes need to try several medication before they find an antidepressant that works well for them.
  10. Therapy is usually needed, too. For mild to moderate depression, therapy and lifestyle changes are considered first-line; however, for moderate to severe depression, a combination of therapy and medication is often helpful. Sometimes antidepressant medications will be used first to alleviate depression enough for therapy to be helpful, Dr. Coplan says. But psychotherapy, cognitive behavioral therapy, or other therapeutic strategies, such as transcranial magnetic stimulation, are also needed for effective depression treatment.
  11. Depression is often experienced with coexisting anxiety. Many people who have one mental health disorder, such as depression, may experience another, such as anxiety or attention deficit hyperactivity disorder. “Anxiety can be as debilitating as depression, but people may have lived with it so long, they don’t realize they actually have anxiety,” says Dr. Solomon, who adds that women are especially vulnerable to anxiety disorders.
  12. Depression profoundly affects people throughout the world. A February 2017 report from the World Health Organization stated that depression is the leading cause of disability in the world, affecting more than 300 million people worldwide. It also showed an 18 percent increase between 2005 and 2015 in the number of people living with depression, the majority of whom are young people, elderly people, and women.

Depression Resources

Many organizations also have online resources for depression, including:

  • NIMH
  • National Alliance on Mental Illness
  • American Psychological Association
  • Depression and Bipolar Support Alliance
  • Anxiety and Depression Association of America

If you’re struggling with suicidal thoughts, go to your nearest emergency room or contact the National Suicide Prevention Lifeline at 800-273-8255 (TALK).

For help finding a therapist, call the Substance Abuse and Mental Health Services Administration (SAMSA)’s National Helpline at 1-800-662-HELP (4357) for a free, confidential referral for treatment.

Additional reporting by Erica Patino