What Causes Depression?


Harvard Medical School recently published an article on the causes of depression; the onset of depression is more complex than a brain chemical imbalance.

The research suggests three areas of the brain that are effected in a patient diagnosed with depression.

  • Amygdala
  • Thalamus
  • Hippocampus

The Amygdala is activated when a person recalls emotionally charged memories, such as a frightening situation.  Activity is higher when a person is sad or clinically depressed.

The Thalamus receives most sensory information and relays it to the appropriate part of the cerebral cortex, which directs high-level functions, such as speech, behavioral reactions, movements, thinking, and learning.

The Hippocampus has a central role in processing long-term memory and recollection.  It is the part of the brain that registers fear.

Working together, these regions of the brain have a direct effect on a person’s mood.  Mood is affected by dozens of genes; such as the following:

  • A person’s temperament effects behavior
  • Stressful life events
  • Stresses on the body
  • Early losses and trauma
  • Seasonal Affective Disorder (SAD)
  • Medical problems

Research suggests that depression doesn’t start from simply having too much or too little of certain brain chemicals.  Rather, there are many possible causes of depression; including faulty mood regulations by the brain, genetic vulnerability, stressful life events, medications, and medical problems.  It’s believed that several of these forces interact to bring on depression.

If you would like to read this article in its entirety, visit their website at

Harvard Medical School

Published:  June 2009, updated April 11, 2017





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