Socioeconomic Position and Somatic Comorbidity in Mental Disorders

Individuals with mental disorders face an elevated risk for somatic noncommunicable diseases (NCD), such as cardiovascular disease (CVDs), chronic obstructive pulmonary disease (COPD), diabetes, and cancer. Low socioeconomic position (SEP) is linked to both mental disorders and somatic NCDs, but its role in this association remains unclear. Here, we provide a comprehensive overview of how associations between mental disorders and somatic NCDs vary by SEP indicators.

Data on all adult individuals resident in Norway from 01.01.2008 to 01.01.2010 (N = 3,589,719) were derived from a nationwide registry linkage including information on primary and secondary health care, dispensed drugs, causes of death, and socioeconomic factors. We assessed four broad types of mental disorders (psychotic, bipolar, depressive and anxiety disorders) and four categories of somatic NCDs (CVD, COPD, diabetes, cancer) diagnosed during follow-up from 01.01.2010 to 31.12.2020. Educational attainment and household income were used as SEP indicators, in addition to parental educational attainment. Cox regression models estimated hazard ratios for somatic NCDs among individuals with mental disorders compared to the general population, adjusting for and stratifying by SEP, sex, and age.

All mental disorders were associated with an increased risk of somatic NCDs, strongest for COPD and weakest for cancer. Risk increased with disorder severity, with psychotic and bipolar disorders showing the strongest associations. Young adults with psychosis had a 4-5-fold increased risk of diabetes and COPD. Low SEP was associated with both mental disorders and somatic NCDs with moderate attenuating effects in their co-occurrence and little variation across SEP strata.

We found an increased risk of somatic NCDs in individuals with mental disorders and identified young adults with psychosis as a particularly vulnerable subgroup. Low SEP compounds this burden, underscoring the need for integrated mental and somatic healthcare strategies.