Antidepressant Use and GDP: Economic Correlates of Mental Health in OECD Countries

Abstract Introduction Antidepressant consumption has risen sharply in high-income countries over the past two decades, driven by both clinical trends and socioeconomic dynamics. Previous studies show strong positive associations between changes in nominal GDP and antidepressant use. However, nominal GDP can misrepresent real purchasing power. This study incorporates GDP adjusted for purchasing-power parity (PPP) to better capture economic conditions and assess how real income fluctuations relate to mental health care utilization. Methods We compiled annual data (2010–2023) on defined daily dosages (DDD) of antidepressants per 1,000 inhabitants per day, alongside nominal and PPP-adjusted GDP for 22 OECD countries. Yearly percentage changes were computed. Analyses included: Spearman's rank correlations between changes in GDP (nominal and PPP) and antidepressant use; Simple linear regressions (ΔAD = β0 + β1 ΔGDP), estimating slopes and R²; Subgroup comparisons of antidepressant change (ΔAD) during years of GDP decline vs. growth/stability. Results Nominal GDP: Strong correlations (ρ = 0.85–0.99, p < 0.01; median ≈ 0.95). Regression slopes ranged 1.8–3.5 (mean R² ≈ 0.75). PPP GDP: Weaker correlation (ρ = 0.597, p = 0.003), β₁ = 2.36, R² = 0.337. Subgroup: GDP-decline years (n = 8) had ΔAD = –78.6% vs. –22.7% in growth/stable years (n = 12). Differences were significant (t-test p = 0.015; U = 0.008). Discussion PPP-adjusted GDP attenuates-but does not eliminate-the correlation between economic growth and antidepressant use. Nominal GDP explains ∼75% of variance, while PPP explains ∼34%, suggesting price-level differences matter. Both nominal and real wealth impact psychiatric medication access. Policymakers should consider PPP trends when forecasting service needs and ensuring care continuity during economic hardship. Key messages • ADPs use rose with GDP across 22 OECD countries. Nominal GDP showed a strong link (ρ ≈ 0.95), while PPP-adjusted GDP showed a weaker one(ρ = 0.597), highlighting economic impact on mental health. • ADPs use dropped 78.6% in GDP-decline years vs. 22.7% in growth years, showing economic downturns significantly reduce access to care - highlighting need for resilient mental health policies.