Change in level of positive mental health as a predictor of future risk of mental illness.

Objectives: We sought to describe the prevalence of mental health and illness, the stability of both diagnoses over time, and whether changes in mental health level predicted mental illness in a cohort group.

Methods: In 2009, we analyzed data from the 1995 and 2005 Midlife in the United States cross-sectional surveys (n = 1723), which measured positive mental health and 12-month mental disorders of major depressive episode, panic, and generalized anxiety disorders.

Results: Population prevalence of any of 3 mental disorders and levels of mental health appeared stable but were dynamic at the individual level. Fifty-two percent of the 17.5% of respondents with any mental illness in 2005 were new cases; one half of those languishing in 1995 improved in 2005, and one half of those flourishing in 1995 declined in 2005. Change in mental health was strongly predictive of prevalence and incidence (operationalized as a new, not necessarily a first, episode) of mental illness in 2005.

Conclusions: Gains in mental health predicted declines in mental illness, supporting the call for public mental health promotion; losses of mental health predicted increases in mental illness, supporting the call for public mental health protection.