Figure 1 presents the age-specific incidence curves for each of the broad classes of lifetime mental disorder. Anxiety disorders occurred earliest with a steep slope beginning in early childhood, and leveling off after age 12. Risk was fairly low for mood and behavior disorders until early adolescence when it began to rise steadily. Substance use disorders appeared to have the latest age of onset with a steep increase in incidence after age 15. The estimated risk at age 18 was 17.6% for behavior disorders, 18.2% for mood disorders, 23.8% for substance use disorders, and 26.2% for anxiety disorders. The median age of disorder onset was 6 for anxiety disorders, 11 for behavior disorders, 13 for mood disorders, and 15 for substance use disorders (data not shown).
