Another study compared cohorts of American adults on the personality trait of neuroticism, which indicates emotional reactivity and is associated with anxiety. Americans scored higher on neuroticism in 1993 than they did in 1963, suggesting that as a population we are becoming more anxious. Another study compared the level of narcissism among cohorts of American college students between 1982 and 2006 and found that more recent cohorts are more narcissistic.
An additional study supports the explanation that more people are diagnosed with mental illness because more of us have mental illness: The more recently an American is born, the more likely he or she is to develop a psychological disorder. Collectively, this line of research indicates that more is going on than simply better detection of mental illness.
--Robin Rosenberg, Slate, on reverse progress