What is depression?
“Depression (major depressive disorder) is a common and serious medical illness that negatively affects how you feel, the way you think and how you act. Fortunately, it is also treatable. Depression causes feelings of sadness and/or a loss of interest in activities once enjoyed.”
The numbers
- It is more common in women than in men.
Watch: What is depression? — Helen M. Farrell for TED-Ed, on symptoms, treatment, and how to help a friend.
In their words
Talking about depression is uncomfortable, but necessary
“Being uncomfortable for a few seconds, minutes or hours is worth it if it saves a life… I got a message on Facebook from my partner, just asking how I was. That saved my life. She saved my life without even knowing it. The littlest things can keep a person living.”
The unexpected symptoms I didn't realize screamed depression
“With depression, you could feel more tired than usual, irritable, and feel more down on yourself and may have no idea you're experiencing depression, because the ‘common’ symptoms most people use to recognize depression are suicidal thoughts, loss of appetite, hopelessness, anxiety, emptiness and depressed mood.”
When I heard someone say some depressed people don't want to get better
“For those of us with clinical depression, more often than not we do want to get better. That is why we take our medications and go to therapy. Just like patients get treatment and have follow-up visits with their doctors… There is a gap between what people think they know about depression and what depression is really like.”
What brain imaging has shown
Brain scanning comes in two kinds, and the difference matters when you read a study. Structural MRI measures the SIZE and shape of a region. Functional scans — fMRI, PET, SPECT — measure ACTIVITY: what changes while someone is doing something. A functional scan cannot tell you how big something is, and a structural one cannot tell you what it was doing. Both have improved our understanding of which regions are involved in mood. Three come up repeatedly in depression research: the amygdala, the hippocampus and the thalamus.
The hippocampus is smaller in some people with depression. In one MRI study of 24 women with a history of recurrent depression, the hippocampus was on average 9% to 13% smaller than in 24 matched women without it, and the longer a woman's total lifetime experience of depression, the smaller it was. It is a structural measurement, of volume. Stress may be the link: prolonged exposure to stress hormones appears to suppress the growth of new neurons there.
That leads to an interesting question about antidepressants. They raise the concentration of neurotransmitters almost immediately, yet people usually do not feel better for several weeks. As Harvard Health puts it:
“The answer may be that mood only improves as nerves grow and form new connections, a process that takes weeks.”
Activity in the amygdala is higher when someone is sad or clinically depressed, and stays higher even after recovery.
How does treatment help?
Treatment can be one thing or a combination, and it is common to combine medical treatment with changes to daily life.
- Medication. A doctor may prescribe antidepressants, antianxiety or antipsychotic medication. Each type has benefits and risks; our guide to medication classes goes through how they work.
- Psychotherapy. Talking to a therapist can teach skills for coping with negative feelings. Family or group sessions help some people too.
- Light therapy. Exposure to doses of white light can help regulate mood, particularly where the depression is seasonal.
A note from the team
We are not experts and do not seek to diagnose or act in place of professional psychiatric treatment. We are an organization seeking to raise awareness. If you have concerns about any of this material, please email us.
Sources
- American Psychiatric Association — What is depression? (the definition)
- Depression and Bipolar Support Alliance — Depression statistics (the numbers)
- Sheline YI et al. — Sheline YI, Sanghavi M, Mintun MA, Gado MH — Depression duration but not age predicts hippocampal volume loss in medically healthy women with recurrent major depression, Journal of Neuroscience 19(12):5034–5043, 1999 (the hippocampus study itself; Harvard Health describes it as an fMRI study, which it is not — it is structural MRI volumetry)
- Harvard Health Publishing — What causes depression? (the brain imaging section)
- Healthline — Depression medication list (the treatment section)