Mental Health Center
Researchers from Harvard Medical School conducted face-to-face surveys of almost 10,000 adults to learn about how common psychological problems are in the general population, and at what ages they begin. The most common specific problem in adults was major depression, followed by alcohol abuse, specific phobias, and social phobias.
The most common broad class of disorders was anxiety disorders, followed by impulse-control disorders, mood disorders, and substance abuse disorders. Across the board, half of all disorders in adults had started by age 14!