Based on the research of Kessler & Wang (2008), psychological problems are very common. About one-half (46.4%) of the US population will experience an anxiety disorder, mood disorder, impulse-control disorder, or substance disorder at some point in their lives. The most prevalent class of disorders is anxiety disorders (28.8%), followed by impulse-control disorders (24.8%), mood disorders (20.8%), and substance use disorders (14.6%). The most prevalent disorders over the lifespan are major depressive disorder (16.6%), alcohol abuse (13.2%), specific phobia (12.5%), and social phobia (12.1%).
In the last 12 months, 18.1% of the population suffered from an anxiety disorder, 9.5% from a mood disorder, 8.9% from an impulse-control disorder, and 3.8% from a substance abuse disorder.
As a reference point, each year the percentage of Americans who get the flu is estimated to be 5 – 20%.
Ronald C. Kessler, & Philip S. Wang. (2008). The Descriptive Epidemiology of Commonly Occurring Mental Disorders in the United States. Annu. Rev. Public Health, 29, 115–29. 