Is the Global Prevalence Rate of Adult Mental Illness Increasing over Time? No, the prevalence increase of adult mental illness is small, mainly related to demographic changes

Richter, Dirk, Abbie Wall, Ashley Bruen, and Richard Whittington. 2019. “Is the Global Prevalence Rate of Adult Mental Illness Increasing over Time? Systematic Review and Meta-analysis of Repeated Cross-sectional Population Surveys.” PsyArXiv. May 6. psyarxiv.com/5a7ye

Abstract
Objectives: The question whether mental illness prevalence rates are increasing is a controversially debated topic. Epidemiological articles and review publications that look into this research issue are often compromised by methodological problems. The present study aimed at using a meta-analysis technique that is usually applied for the analysis of intervention studies to achieve more transparency and statistical precision.

Methods: We searched Pubmed, PsycInfo, CINAHL, Google Scholar and reference lists for repeated cross-sectional population studies on prevalence rates of adult mental illness based on ICD- or DSM-based diagnoses, symptom scales and distress scales that used the same methodological approach at least twice in the same geographical region. The study is registered with PROSPERO (CRD42018090959).

Results: We included 44 samples from 42 publications, representing 1,035,697 primary observations for the first time point and 783,897 primary observations for the second and last time point. Controlling for a hierarchical data structure, we found an overall global prevalence increase odds ratio of 1.179 (95%-CI: 1.065 – 1.305). A multivariate meta-regression suggested relevant associations with methodological characteristics of included studies.

Conclusions: We conclude that the prevalence increase of adult mental illness is small and we assume that this increase is mainly related to demographic changes.