General Information on Depression

One of the most prevalent forms of psychological distress, depression touches millions of lives across the world.

Prevalence and Impact of Clinical Depression

Estimates vary considerably, but many studies suggest that 5-17% of the general population will experience major depressive disorder at some point in their lives. One recent large-scale study indicated a lifetime prevalence in the US of 16%. The US National Institute of Mental Health cites evidence that nearly 10% of individuals in the United States experience some variety of depressive condition in any one-year period. The majority of sufferers experience recurring episodes over their lifetimes, with the likelihood of recurrence increasing with every successive episode. The average duration of an episode of major depression is 6 months, but some people may suffer for years.

Disability associated with clinical depression is reportedly greater than that for many chronic physical conditions, including hypertension, diabetes, arthritis and back pain. Depression is associated with increased risk of cardiovascular disease in general and myocardial infarction (heart attack) in particular. It is also associated with a significant increase in overall probability of death from all causes, with this effect more pronounced in men.

When disability is taken into consideration, rather than just death, the impact of mental health problems in general, including depression as a major component of the overall set of mental health problems, ranks near cardiovascular and respiratory diseases in terms of overall impact. In the US alone, it has recently been estimated that depression costs $44 billion in health-related lost productive time every year.

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Further Reading on Depression

Our separate annotated bibliography contains references to additional print resources on depression. Figures on the global impact of depression are taken from Murray and Lopez (1996) and Üstün and Chatterji (2001), while Richards and Perri (2002) provide information on associations with risk of cardiovascular disease. One source of evidence on increased risk of death is Zheng, et al (1997). Kessler, et al (2003) suggest the 16% lifetime prevalence figure from a study of over 9000 people, while Stewart, et al (2003) provide the $44 billion estimate of lost productive time.