Mood Disorders: Depression, Dysthymic Disorder & Bipolar Disorder

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  • 0:53 Depression
  • 2:40 Biological Causes
  • 3:30 Psychological Traits
  • 4:53 Bipolar Disorder
  • 6:17 Suicide
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Lesson Transcript
Instructor: Ellie Green

Ellie holds a B.A. with Honors in English from Stanford University. She is pursuing a Ph.D. in English Literature at Princeton University.

Does feeling sad automatically mean someone is depressed? Are there different kinds of depression? What are mood disorders? This lesson will take a look at the answers to those questions.

Major Depression

Jim's been feeling down lately. He got fired from his job as a line cook and isn't sure what he'd like to do next. He knows he should try to find more work, but in this economy it doesn't seem worth it to try. He's been sleeping later and later because he doesn't have much to do, and he's been feeling really tired.

As he goes longer without work, he starts feeling sad. Jim tries to go out with friends, but they're all employed and he finds them irritating to be around. They stop calling.

Jim still hasn't found work, and starts feeling like he never will; starts feeling worthless. Now he spends most of his day sleeping. He doesn't have the energy to cook, so he eats junk food all the time.

So what's going on with Jim? If you were Jim's therapist, what diagnosis would you reach?

You might suspect that he's depressed, because he mentions feeling sad. Feeling sad isn't enough on its own, though - we all feel sad sometimes.

But Jim has also mentioned changes in his sleep and eating patterns. He's lost interest in hanging out with his friends, and feels irritable with them. He feels worthless because he hasn't found a job yet. Furthermore, it seems that his depressed mood is preventing him from finding a new job.

Jim is demonstrating most of the signs of major depression, a mood disorder which affects 8%-12% of people at some point during their lives.

Jim does not have recurrent suicidal thoughts. We'll talk more about suicide near the end of this lesson.

Even so, since he has many other items of a depression diagnostic checklist, you might diagnose him as having a 'major depressive episode' anyway.

It's understandable that Jim would feel sad after losing his job - what makes Jim's experience 'major depression' are his other symptoms, and their duration of longer than two weeks.

Major depressive episodes are often set off by traumatizing events, like the loss of a job or the death of a loved one, but it's a reaction that's beyond normal sadness or grief.

Susceptibility to major depression is believed to have biological underpinnings. Low levels of serotonin and norepinephrine have been observed in depressed patients. There are also differences in actual brain structure; the basal ganglia, thalamus and hippocampus are all differently shaped. Interestingly, it's been shown that increasing serotonin levels in the brain can actually stimulate growth in the hippocampus, so it's possible that these things are related.

Differences in brain structure may contribute to major depression
Brain Structure Diagram

Depression is associated with certain psychological traits:

Low self-esteem

General negative emotionality

Tendency to blame self for bad things that happen

It's also been associated with social isolation. It's not clear whether social isolation causes depression, or depression causes social isolation.

Dysthymic Disorder

Now let's talk about Sandra. Nothing out of the ordinary has happened to Sandra lately. Still, she's felt unhappy for a long time, with symptoms similar to Jim's but milder.

If you were Sandra's therapist, you might diagnose dysthymic disorder. This is a milder, more long-lasting form of depression. If you experience mild depressive symptoms for over two years, you might have dysthymic disorder. It's treated similarly to depression.

Bipolar Disorder

Now let's imagine mood as a spectrum; depression and dysthymia both make people hang out for longer in the depressive end. Bipolar disorder is just what it sounds like; it makes people hang out at BOTH ends, or 'poles,' of this mood spectrum. They have episodes similar to those in major depressive disorder, followed by periods of mania.

Mania is characterized by:

Feeling of being high

Decreased need for sleep

Inflated self-esteem

Fast speech

General agitation

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