A growing body of evidence indicates that the incidence and prevalence of psychiatric disorders are elevated in persons with IMIDs as compared to the general population. The association between IMIDs and psychiatric disorders appears to be bidirectional, and the increased incidence of psychiatric disorders is not simply due to the challenges of living with a chronic disease.
With respect to common etiologic factors, several pleiotropic genetic loci are jointly associated with the risk of psychiatric disorders and IMIDs, as shown by an analysis of genome‐wide association studies of five psychiatric disorders (major depressive disorder, bipolar disorder, schizophrenia, autism spectrum disorder and attention‐deficit/hyperactivity disorder) and seven immune‐mediated disorders (Crohn's disease, rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, type 1 diabetes, systemic lupus erythematosus and psoriasis) .
Notably, shared genetic loci related to immune function were prominent. In addition to genetic factors, psychosocial factors also influence immune system function and inflammation. Acute stress leads to activation of the autonomic nervous system and hypothalamic‐pituitary‐adrenal axis, and upregulates inflammation. Chronic stress, such as childhood maltreatment, increases inflammation and suppresses cellular and humoral immunity.
In turn, these changes increase the risk of chronic diseases such as IMIDs and psychiatric disorders. Hence, taking care of the psychiatric illnesses and psychological stress factors leads to overall improved functioning and quality of life in people who suffer from IMIDs.