Epidemiology of depression

Area of Science:

• Psychiatry
• Epidemiology
• Mental Health Research

Background:

• Published literature indicates varying 1-year prevalence rates for major depressive disorder (2.6-6.2%), dysthymia (2.3-3.7%), and bipolar disorder (1.0-1.7%).
• Lifetime prevalence estimates based on recall may underestimate true mood disorder morbidity.

Purpose of the Study:

• To determine the 10-year prevalence rates of various affective disorders.
• To assess the treatment rates for diagnosed affective disorders in a prospective cohort.

Main Methods:

• Prospective Zurich Study involving four interviews over a 10-year period.
• Analysis of prevalence and treatment data for major depression, recurrent brief depression, dysthymia, bipolar disorder, and hypomania.

Main Results:

• 10-year prevalence rates for subjects aged 20-30 were: major depression (14.4%), recurrent brief depression (10.5%), dysthymia (0.9%), bipolar disorder (3.3%), and hypomania (1.3%).
• An average of 49% of diagnosed cases received treatment for affective disorders.
• Weighted treatment prevalence was 11.6% overall, with 18% for females and 5% for males.

Conclusions:

• Affective disorders exhibit substantial prevalence over a 10-year period, particularly in younger adults.
• Treatment rates for mood disorders are significant, though a considerable portion of affected individuals do not receive treatment.
• Prospective studies offer more accurate morbidity data than retrospective recall methods.