The Oxytocin Genetic Pathway Links Severe Mental Illness and Metabolic Syndrome

Oxytocin is a hormone that is primarily produced in the brain, which has traditionally been associated with childbirth, breastfeeding, and social behaviour. However, more recent evidence has also suggested a link with cardiovascular conditions and diabetes. One-third of patients with bipolar disorder and schizophrenia suffer from metabolic syndrome, which is a cluster of conditions (such as increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal blood fat levels) that occur together, increasing your risk of heart disease, stroke, and type 2 diabetes. Moreover, the reported rates of loneliness are ~2.3 times higher in patients with schizophrenia and bipolar disorder than in the general population. Emerging evidence has linked the genes underlying the oxytocin system to various potential causes of both psychiatric symptoms and metabolic syndrome in schizophrenia and bipolar disorder. Therefore, the aim of this thesis was to investigate the contribution of these oxytocin genes to the overlap between severe mental illness and metabolic disorders in just under half a million individuals. The findings of this thesis point to a wide-ranging involvement of oxytocin in a variety of mechanisms tied to cardiovascular and metabolic disease, such as bone density and where fat accumulates on the body, as well as dietary behaviours such as portion size and the sugar content of meals. The oxytocin system was also found to be involved in various social features of psychiatric disorders, such as loneliness. Altogether, this work points to oxytocin’s therapeutic potential for a variety of conditions