Q. Can you give me a definition or description of depression?

A. You’ve probably heard one common description that says depression is anger turned inward. Another is that some type of fear underlies depression. A medical dictionary defined depression as a mental state characterized by feelings of sadness, despair, and discouragement.

One challenge in coming up with a definition is that several different types of depression have been identified, including:

• Situational depression (contextual or event-related)
• Premenstrual dysphoric disorder
• Bipolar disorder or manic depressive illness
• Major depressive disorder
• Dysthymia or chronic depression

Joseph LeDoux, author of The Synaptic Self, believes that depression is not a single clinical condition, but (like schizophrenia) it involves altered circuits in the brain. Because each brain is different and the way in which the circuits are altered is unique to each brain, the same treatment doesn’t work the same on all depressed people.

Some estimates are that about 15% of the population experiences some type of depression at any given time. According to Doc Childre, depression was the 4th leading cause of disease-burden in 1990, and by 2020 it is estimated that it will be the single leading cause of disease-burden.