The good old days? Mental health across birth cohorts

The share of young Australians reporting poor mental health has risen sharply over the past two decades, a pattern mirrored across many high-income countries. A central question is whether this reflects a genuine deterioration in underlying mental health or shifts in how different birth cohorts report their symptoms. Using 22 years of nationally representative longitudinal survey data from Australia (2002-2023), we construct a predicted mental health index from respondents' socioeconomic characteristics, childhood conditions, physical health, life events, and financial circumstances, and compare it against self-reported mental health to isolate cohort-specific reporting differences. We find that the answer is both, namely, that younger cohorts apply lower thresholds when reporting distress, reflecting greater willingness to acknowledge poor mental health, and underlying mental health has genuinely deteriorated among recent cohorts, particularly females. Adjusting for cohort-specific reporting thresholds flattens the apparent rise in poor mental health, though a deterioration remains. After adjustment, the age gradient steepens, revealing that poor mental health peaks in mid-life, a life-cycle pattern that is obscured in raw self-reports. Our findings underscore the importance of accounting for reporting heterogeneity when interpreting mental health trends and planning health services.