Although it may be surprising to many people, forms of depression are among some of the most common health conditions out there. Major Depressive Disorder is the most commonly diagnosed form of depression. Because of the frequency with which it is seen, depression is sometimes nicknamed the “common cold” of mental health. However, this nickname does not appropriately convey the suffering and disruption that is often experienced by those with depression and their loved ones. Depression can strike at any age from toddlers to older adults. But it most often begins in adolescence or early adulthood. Women are more commonly diagnosed than men. For example, Major Depressive Disorder is diagnosed 2-3 times more often in women than men in the United States (Kessler et al., 2003).
In the United States, the most recent estimates suggest that about 16% of people will experience Major Depressive Disorder (MDD) at some point in their lives. In a given year, about 7% will experience MDD (Kessler et al., 2003). The prevalence of depression has also been steadily increasing since after World War II. Thus, the lifetime prevalence of depression may be more like 25% for today’s younger generations. Yes, that’s right….As many as one out of four young people may experience diagnosable depression over the course of their lives. There have not been comprehensive studies that have looked at prevalence of all the depressive disorders combined. However, the prevalence would likely be at least 2-3% higher when adding in other less common forms of depression such as Persistent Depressive Disorder and Bipolar Disorder (DSM-5).
The prevalence of depression differs widely across countries. However, average estimates suggest that 10-15% of the worldwide population will experience depression at some point in their lives (WHO, 2004). In another recent worldwide survey, about 5% of people reported experiencing depression sometime during the past year (Lepine & Briley, 2011). These numbers are lower than US estimates, and there are various theories as to why they may be lower. Depression may be less common in some countries because certain lifestyles include more factors that protect against depression (e.g. regular exercise, regular light exposure, diet). Stigma that makes people reluctant to endorse symptoms of depression is also likely more of a factor in some countries than others.
Kessler, R. C., Berglund, P., Demler, O., Jin, R., Koretz, D., Merikangas, K. R., . . . Wang, P. S. (2003). The epidemiology of major depressive disorder: results from the National Comorbidity Survey Replication (NCS-R). Jama, 289(23), 3095-3105. doi:10.1001/jama.289.23.3095
Lepine, J. P., & Briley, M. (2011). The increasing burden of depression. Neuropsychiatr Dis Treat, 7(Suppl 1), 3-7. doi:10.2147/ndt.s19617