Background: Only a limited number of population-based studies have been able to prospectively follow the mental health of their participants. We aimed to describe diagnostic changes in a population based cohort over a two year period, and to explore associations between a range of individual factors and recovery from, or onset of, disorders.
Methods: Two year, face-to-face follow-up of a community-based cohort drawn from random telephone screening using the CIDI as diagnostic instrument. Unlike most similar research we did not exclude individuals with prior history from analysis.
Results: 1407 participants were administered face-to-face interviews and 968 were re-interviewed. In multivariate analysis, recent adverse life events, poor physical health, and high neuroticism score were significant predictors of developing a mental disorder in participants who were disorder free at baseline. Higher baseline levels of physical activity were protective of new disorders in univariate analysis. Most participants with a baseline disorder and not lost to follow-up were disorder-free two years later. For participants with a disorder at both interviews, there was marked lability in diagnoses, with only a small minority having an unchanged diagnosis at both baseline and follow-up. Factors predicting a poor outcome in participants with a disorder included the number of baseline diagnoses, high neuroticism score and adverse life events.
Conclusions: These findings suggest that the diagnosis of common mental disorders is complex and that diagnoses are relatively unstable. The factors that influence the emergence of mental disorders in individuals who may, or may not, have had a disorder in the past, are similar to those associated with the development of new disorders in subjects without a lifetime history.