FIGURE 13.1 Age of Onset and the Lifetime Prevalence of Psychological Disorders The graph on the left shows the median age of onset for common categories of psychological disorders in the National Comorbidity Survey Replication (NCS-R). While the onset of anxiety, posttraumatic stress, and obsessive–compulsive disorders or impulse-control disorders tends to occur in the preteen years, the onset of depressive and bipolar disorders typically occurs around age 30, well into young adulthood. The graph on the right shows the lifetime prevalence for the same categories. The NCS-R reconfirmed that the lifetime prevalence of experiencing a psychological disorder is almost one out of two. The bars in the graph on the right add up to more than 100% because some people are diagnosed with more than one disorder.