Depressive and Bipolar Disorders

Depression: Low, sad state marked by significant levels of sadness, lack of energy, low self-worth, guilt, or related symptoms

Mania: State or episode of euphoria or frenzied activity in which people may have an exaggerated belief that the world is theirs for the taking

Depressive disorders: A group of disorders marked by unipolar depression

Unipolar depression: Depression without a history of mania

Bipolar disorder: Disorder marked by alternating or intermixed periods of mania and depression

Unipolar Depression: The Depressive Disorders

• 8 percent of U.S. adults experience severe unipolar depression in any given year; 5 percent experience mild forms

• 20 percent of all adults experience unipolar depression at some time in their lives

• Lifetime prevalence: 26 percent of women versus 12 percent of men

• The average age of onset is 19 years

• The rate of severe depression is twice as high among adults under 65 years of age as among those 65 years and older

• Approximately 85 percent of people with unipolar depression recover, some without treatment

• Around half will experience another episode later in their lives

Major depressive episode

• For a 2-week period, a person displays an increase in a depressed mood for the majority of each day and/or a decrease in enjoyment or interest across most activities for the majority of each day.

• Significant distress or impairment

For the same 2 weeks, a person also experiences at least 3 or 4 of the following symptoms:

1. Considerable weight change or appetite change

2. Daily insomnia or hypersomnia

3. Daily agitation or decrease in motor activity

4. Daily fatigue or lethargy

5. Daily feelings of worthlessness or excessive guilt

6. Daily reduction in concentration or decisiveness

7. Repeated focus on death or suicide, a suicide plan, or a suicide attempt.

What Causes Unipolar Depression?

Biological view

• Studies of genetic factors and biochemical factors suggest unipolar depression has biological causes

Genetic factors

• Family pedigree studies

• Twin studies: 38% concordance among MZ twins, 20% in DZ

• People who are depressed can have an abnormality of their 5-HTT gene, a gene located on chromosome 17

• Gene studies

Biochemical factors

• Low activity of two neurotransmitters: serotonin and norepinephrine

• In the 1950s, blood pressure medications that lower serotonin/norepinephrine often led to depression

• Antidepressant drugs bring about increases in norepinephrine and/or serotonin activity

• Now, interactions between serotonin, norepinephrine activity, and other neurotransmitters in the brain are considered

Hormones and HPA pathway

• HPA pathways are overly reactive in people with depression

Psychological Views: Psychodynamic view

• Freud and Abraham: When some people experience real or symbolic loss (e.g., job loss, breakup, identity)

• Introjection: feelings for the loved one, including sadness and anger, directed toward themselves

• If dependency needs were improperly met during infancy and early childhood, grief worsens over time, and they develop clinical depression

• Object relations theorists: Depression results when people's relationships (especially early ones) leave them feeling unsafe and insecure

• General research support: Depression may be triggered by major loss; early losses set the stage for later depression

• People whose childhood needs were poorly met are particularly likely to become depressed after experiencing a loss

• Early losses and inadequate parenting sometimes lead to depression but may not be typically responsible for the development of the disorder

Bipolar Disorder

What causes bipolar disorders?
Biological research and perspectives:

• Genetic factors

• Many theorists believe that people inherit a biological
  predisposition to develop bipolar disorders

• Family pedigree studies: MZ twins have a 40% concordance rate,
  siblings have a 5-10% likelihood

• Bipolar disorders linked to genes on chromosomes 1, 4, 6, 10, 11, 12, 13, 15, 18, 20, 21, and 22 (number of genetic abnormalities probably combine)