Study Explores the Socioeconomic Position Role in the Association Between Mental Disorders, Mortality

Credit: Aarhus University

A new study found mental disorders are associated with higher mortality, and socioeconomic positions do not significantly affect mortality rates. Therefore, the limited evidence suggested socioeconomic positions do not play a significant role in the association between mental disorders and mortality.¹

A 2015 meta-analysis demonstrated mortality rates are 2- to 3-fold higher than people with mental disorders than people without mental disorders. Not only that, but people with mental disorders have a shorter life expectancy—now 7 – 10 years shorter than the average life span. According to the University of Oxford, the average life expectancy reduction in people with mental disorders is:

• Bipolar disorder (reduced 9 – 20 years)
• Schizophrenia (reduced 10 – 20 years)
• Drug and alcohol abuse (reduced 9 – 24 years)
• Recurrent depression (reduced 7 – 11 years).²

To put it into perspective, the life expectancy for heavy smokers is cut 8 – 10 years. Yet, people with mental disorders have just as high or a higher mortality risk than smokers.

“Given that mental disorders are common, understanding the risk factors of this excess mortality is crucial,” the investigators of the new study wrote.¹

The new systematic review and meta-analysis, led by Danni Chen, MSc, of the department of clinical epidemiology at Aarhus University and Arhus University Hospital in Denmark, sought to evaluate the role of socioeconomic position in the association between mental disorders and mortality, as well as the association between socioeconomic positions and mortality among people with mental disorders. Already, the investigators knew low socioeconomic positions are associated with an increased risk of mental disorders, including ADHD, schizophrenia, and depression.

After screening 28,274 articles, the investigators included 71, which consisted of > 4 million people with mental disorders. The team considered mental disorders as any mental disorder detected by a diagnosis criterion through registers, records, or diagnostic interview. They also looked at 4 socioeconomic positions: income, education, occupation/employment, and socioeconomic position index.

Primary outcomes included all-cause and cause-specific mortality. Cause-specific mortality was categorized as external causes (for example, suicides, unintentional deaths, and homicides), and natural causes.

After looking at the data, the team found associations between mental disorders and mortality were comparable across socioeconomic positions. The highest socioeconomic group was associated with lower morality rates for any disorder, disease, or condition (pooled relative risk [RR], 0.79; 95% CI, 0.73 – 0.86), lower morality from natural causes (RR, 0.73; 95% CI, 0.62 – 0.85), and higher morality from external causes (RR, 1.18; 95% CI, 0.99 – 1.41).

“Notable finding was that people with mental disorders and higher rather than lower [socioeconomic positions] had a greater risk of mortality due to external causes,” the investigators wrote. “The mechanisms underlying these findings are not fully known… Individuals from low [socioeconomic position] groups may have limited access, continuity, and quality of care, thus leading to poor disease control and increased comorbidities.”

Despite the findings, the investigators could not find “sufficient body of evidence” on socioeconomic position’s role on mortality rates among people with mental disorders for all-cause mortality (2.23; 95% CI, 1.56 – 3.19) external causes (8.02; 95% CI, 5.14 – 12.54) and natural causes (2.56; 95% CI, 1.48 – 4.43)

Subgroup analyses found no differences according to sex, age group, and geographic location but did for specific schizophrenia, depression, and alcohol use disorders. All-cause mortality in schizophrenia (RR, 4.03; 95% CI, 3.81 – 4.25) was higher than that in depression (RR, 1.78; 95% CI, 1.63 – 1.94) or alcohol use disorders (RR, 1.72; 95% CI, 0.54 – 5.52).

“Low [socioeconomic positions] may indirectly cause mortality through increasing risk factors (eg, poor diet, smoking, alcohol, drugs, obesity, and social exclusion),” the investigators wrote. “Another potential explanation is that people with higher education or income may feel more shameful, vulnerable, and stigmatized when they have mental disorders, thus potentially leading to a delay in diagnoses (and thus at a more severe stage) and higher risk of suicide.”

^References

1. ^{Chen D, Ejlskov L, Laustsen LM, et al. The Role of Socioeconomic Position in the Association Between Mental Disorders and Mortality: A Systematic Review and Meta-Analysis. JAMA Psychiatry. Published online November 15, 2023. doi:10.1001/jamapsychiatry.2023.4316}
2. ^{Many Mental Illnesses Reduce Life Expectancy More Than Heavy Smoking. University of Oxford. May 23, 2014. https://www.ox.ac.uk/news/2014-05-23-many-mental-illnesses-reduce-life-expectancy-more-heavy-smoking. Accessed November 27, 2023.}