Is the Worldwide Prevalence of Mental Illness Increasing Dramatically?

Despite media reports to the contrary, the global prevalence of adult mental illness is not increasing dramatically, according to a meta-analysis published in Acta Psychiatrica Scandinavica. Although increased use of mental healthcare services and elevated incidence of suicide point to a major social crisis, the study found the rising prevalence of mental illness to be fairly small and possibly linked to demographic shifts.

The researchers wrote, “The claim of rising mental illness…would have important implications not only for public mental health in terms of potential failure of treatment approaches but also for wider society in terms of understanding living conditions that sociologists see to be deteriorating and…social suffering or social pathology.”

Dirk Richter, PhD, from Bern University Hospital for Mental Health in Switzerland, and colleagues searched PubMed, PsychINFO, CINAHL, Google Scholar, and reference lists for cross-sectional population studies on prevalence rates of adult mental illness. Longitudinal, cohort, and treatment prevalence studies were excluded from the analysis. The authors included 44 samples from 42 publications conducted between 1978 and 2015, representing 1,035,697 primary observations for the first time point and 783,897 primary observations for the second and last time point.

The sample included several geographic regions: 20 studies from Western Europe, 16 from North America, 3 each from Asia and Oceania, and 1 each from the Middle East and South America. Of these, 4 samples covered the entire range of mental disorders, with the exception of schizophrenia, using the Diagnostic and Statistical Manual of Mental Disorders/International Classification of Diseases-related clinical interview; 20 samples used the Diagnostic and Statistical Manual of Mental Disorders/International Classification of Diseases-related clinical interviews on single disorders, 7 samples used symptom scales, and 13 used distress scales.

The univariate pooled odds ratio for all samples combined was 1.179, but the Q-test for heterogeneity was highly significant (Q (df = 43) = 1693.1; P <.0001). For specific disease states, the odds ratios were 1.046 for general mental illness, 1.126 for distress, 1.298 for depression, 1.016 for alcohol dependence, 1.999 for drug dependence, 1.679 for medication dependence, 1.449 for anxiety, 2.836 for bipolar disorder, and 0.906 for eating disorders.

Limitations of the study included small sample sizes from geographic regions outside Western Europe and North America, as well as the possibility of studies with negative findings not being published, and thus available for analysis.

In an accompanying editorial,² Toshi A. Furukawa, MD, PhD, from the Department of Health Promotion and Human Behavior, Kyoto University Graduate School of Medicine/School of Public Health in Japan, noted: “The prevalence of common mental disorders may be increasing modestly in the recent decades, but this increase is mainly driven by population aging and growth.”

The authors of the meta-analysis caution that mental illness should be taken seriously nonetheless, adding that better treatment availability and awareness may account for some of the perception of increased prevalence. However, Dr Furukawa questions whether a treatment or quality gap remains.

Disclosure: The authors of the review and meta-analysis report no conflict of interest. T. Furukawa reports receiving personal fees from Mitsubishi-Tanabe and MSD, and a grant from Mitsubishi-Tanabe.

References

1. Richter D, Wall A, Bruen A, Whittington R. Is the global prevalence rate of adult mental illness increasing? Systematic review and meta-analysis. Acta Psychiatr Scand. 2019;140:393-407.

2. Furukawa TA. An epidemic or a plaque of common mental disorders? Acta Psychiatr Scand. 2019;140:391-392.