Background and objective:
It is often claimed that mental health issues have become increasingly prevalent, especially among young people from more recent generations. This has been described as the advent of a new ‘age of melancholy’ or ‘age of depression’ originating in changes in social and economic conditions. However, surprisingly little is known empirically about to extent to which these popular claims actually apply in modern societies. This study assessed contemporary trends in mental health and their drivers using high-quality panel data in a cross-national perspective.

Methods:
I used longitudinal data on mental health from ten different countries (n = 329,321 individuals, N = 1,534,863 observations) collected between 1991 and 2020, focusing on the age range between 18 and 79 and the birth cohort range between 1930 and 2000. Each of the datasets contained some commonly accepted instrument for measuring mental health in the general population (e.g. GHQ-12, CES-D-10, SF-12). After assessing the presence of general period trends, I applied hierarchical linear growth curve modeling to account simultaneously for change with age, change across cohorts, and change in age patterns across cohorts. Finally, I investigated if intercohort trends in mental health could be explained by compositional changes in education distribution, household income, marital status, and number of children.

Results:
Though some countries showed a decrease in mental health across periods and across cohorts, others showed no change, and still others showed an improvement. Adding covariates to the models made cohort effects more negative in some countries, while it did not change cohort effects in others.

Conclusion:
Rather than being a global phenomenon, developments in mental health differ substantially across countries. This heterogeneity likely reflects a variety of social and institutional factors driving changes in mental health trajectories.