Chronic inflammation has been linked to an increased risk for various psychiatric disorders. It thus follows that if inflammation plays a mechanistic role in mental health conditions, people with chronic inflammatory conditions may experience more mental health issues. Researchers tested this hypothesis in the current study.
To do so, they analyzed data from over 1.5 million adults living in the UK via the UK-wide Future Health research cohort. They split participants into two groups: those with self-reported lifetime diagnoses of six autoimmune conditions, and those without. Autoimmune conditions included rheumatoid arthritis, Graves’ syndrome, inflammatory bowel disease, lupus, multiple sclerosis, and psoriasis. These conditions served as a proxy for exposure to chronic inflammation. Participants were an average of 53 years old, and 37, 800 reported autoimmune conditions.
The researchers had two primary objectives. The first was to evaluate the prevalence of affective disorders- defined as depression, bipolar disorder, and anxiety disorder- among those with autoimmune conditions. The second was to quantify the excess risk of experiencing affective disorders in this group compared to the population at large.
Ultimately, they found that those with autoimmune disorders have an 87-97% higher risk of affective disorders than the general population. While 29% of people with an affective disorder had been diagnosed with an affective disorder, the same was true for just 18% of the general population. They further found that the link was stronger in women- 32% of women with autoimmune disorders had an affective disorder, whereas the same was true for 21% of men with autoimmune disorders.
The mechanisms underlying the higher prevalence of autoimmune conditions in women are yet to be 'resolved', wrote the researchers in their study. They noted, however, that theories suggest sex hormones, chromosomal factors, and differences in circulating antibodies may partly explain any sex differences.
“Although the observational design of this study does not allow for direct inference of causal mechanisms, this analysis of a large national dataset suggests that chronic exposure to systemic inflammation may be linked to a greater risk for affective disorders. Future work should seek to investigate potential causal mechanisms for these associations,” they concluded.
Sources: EurekAlert, BMJ Mental Health
