Lecture 2.3: Epidemiology of Mood Disorders

Cross-cultural differences

Vocabulary and social differences make the epidemiology of mood disorders difficult to investigate.

• Symptoms are interpreted differently and emotions have different expressions.

• Most studies indicate, however, that clinical depression is a universal phenomenon (although symptoms may vary considerably from culture to culture).

Bipolar Disorder Prevalence

Lifetime prevalence of I or II: ~4%

• One year prevalence:

  • Bipolar I: .6%

  • Bipolar II (Hypomania): .8%

  • Cyclothymia: .4-1%

Average duration of a manic episode is 2-3 months; bipolar II patients tend to have shorter and less severe episodes.

Elderly People

Mood disorders are less common among elderly people than they are among younger adults.

• Certain subgroups of the elderly population, however, may have high incidence of mood disorders (e.g., those about to enter residential care).

Birth cohort trend

One grouping of individuals, according to age, appears to carry the experience of a mood disorder across time.

Ex. Those born after WWII are more likely to develop mood disorders and have an earlier age of onset than people from previous generations.