The link between low socioeconomic status and the increased risk of developing a mental disorder has been long established in the literature. However, past studies have largely excluded personal income as a measurement of socioeconomic position (SEP) because it is not always readily available to researchers, despite its direct measure of an individual’s access to economic and material resources. This changed when a recent study by Hakulinen and colleagues, published in 2023 in the Journal of Epidemiology and Community Health, measured SEP by educational attainment, employment status, and personal income. The primary aim of the study was to first establish the association between SEP at the age of 30 and the risk of developing a common mental disorder.
A nationwide cohort study utilised national registries in Finland to identify 1.2 million Finnish participants born between 1966 and 1986 who turned 30 at the end of the year and followed until their first diagnosis of a mental disorder or until the study period of 22 years ended. The researchers found that having low educational attainment, being unemployed or outside of the labour force, or having low personal income at 30 increased the risk of being diagnosed with a common mental disorder later in life. The common mental disorders measured in this study were substance misuse disorders, schizophrenia spectrum disorders, mood disorders, and anxiety disorders, which collectively greatly contribute to the global health burden.
Mental health disorders such as anxiety disorder are widely prevalent around the world. GlobalData epidemiologists predict there will be just over 293 million lifetime total prevalent cases of men and women living with anxiety disorders alone in the 16 major pharmaceutical markets (16MM: US, France, Germany, Italy, Spain, UK, Japan, Australia, Brazil, Canada, China, India, Mexico, Russia, South Africa, and South Korea) by the end of 2023, and that number is expected to increase to over 302 million cases by the end of 2028. GlobalData epidemiologists also estimate that by the end of 2023, there will be over 14 million 12-month diagnosed prevalent cases of men and women diagnosed with schizophrenia in the 16MM, and that number is predicted to increase to just over 15 million cases by the end of 2031.
By the end of the 22-year study follow-up, the researchers saw that 38% of participants who were employed at the age of 30 were diagnosed with a mental disorder by the age of 52; comparatively, the statistics for those who were unemployed or outside the labor force were 59% and 62%, respectively. Of those who had only completed primary education, 58% were diagnosed with a mental disorder by age 52; the corresponding statistics for those with secondary or higher education were 45% and 36%, respectively. Finally, 63% of those in the lowest income quintile were diagnosed with a mental disorder by age 52, whereas 25% of those in the highest income quintile were diagnosed with a mental disorder by age 52.
Having a lower SEP by age 30 was associated with a higher risk of being diagnosed with any one mental disorder. The demographic at the greatest risk of developing a mental disorder later in life was those in the lowest income quintile, which was associated with a 4.9-fold risk of later substance misuse disorder and a 5.5-fold risk of later schizophrenia spectrum disorder, compared to those in the highest income quintile. The lowest risk of a mental disorder diagnosis was consistently found among those who were employed, had higher education, or had high personal income at 30.
Quantifying the predictive power of measures of SEP on the risk of a diagnosis of a mental disorder later in life can be of great relevance and importance to both research and public policy settings, especially in alleviating the burden of mental disorders worldwide.