Somatic morbidity in bipolar disorders

This Swedish nationwide cohort study used large-scale data to investigate the associations between bipolar disorder and somatic disorders and whether these risks differ by subtype, sex, or exposure to compulsory care.

61,071 individuals diagnosed with bipolar disorder in inpatient (from 1973) or outpatient care (from 2001) care were compared with the general population without bipolar disorder. The cohort included individuals born in 1932 or later, with follow-up from 1973 to 2020. Cox regression models estimated associations with a range of somatic conditions, including cardiovascular, endocrine, neurological, and infectious diseases. Subtype-specific analyses were conducted in individuals with type 1 (n = 8,352) or type 2 (n = 9,674), and in those with a history of compulsory care (n = 6,748).

Bipolar disorder was associated with significantly increased risks for most examined somatic conditions. The highest hazard ratios (HRs) were observed for sleep disorders (HR 3.79; 95% CI, 3.71-3.87) and dementias (HR 4.32; 95% CI, 3.82-4.79). Type 2 diabetes risk was elevated, while no association was found for type 1 diabetes. Most risks were comparable across bipolar subtypes, though certain conditions-such as migraine and fibromyalgia-were more strongly associated with type 2. Individuals with a history of compulsory psychiatric care showed elevated risks for several conditions.

Regardless of sex or subtype, bipolar disorder is associated with substantially higher lifetime risks of a broad range of somatic conditions. Integrated psychiatric and somatic health care may help reduce morbidity and improve outcomes.