Bipolar disorder and the metabolic syndrome: causal factors, psychiatric outcomes and economic burden

Overweight and obesity are highly prevalent in patients with bipolar disorder, and metabolic disorders also affect a significant portion of this population. Obesity and metabolic disorders cause significant economic burden and impair quality of life in both the general population and patients with bipolar disorder. This review examines the relationship between bipolar disorder and the metabolic syndrome, and the associated economic impact. The metabolic syndrome and bipolar disorder appear to share common risk factors, including endocrine disturbances, dysregulation of the sympathetic nervous system, and behaviour patterns, such as physical inactivity and overeating. In addition, many of the commonly used pharmacological treatments for bipolar disorder may intensify the medical burden in bipolar patients by causing weight gain and metabolic disturbances, including alterations in lipid and glucose metabolism, which can result in an increased risk for diabetes mellitus, hypertension, dyslipidaemia, cardiovascular disease and the metabolic syndrome. These medical co-morbidities and obesity have been associated with a worse disease course and likely contribute to the premature mortality observed in bipolar patients. Weight gain is also a major cause of treatment noncompliance, increased use of outpatient and inpatient services and, consequently, higher healthcare costs. Prevention of weight gain and metabolic disturbances or early intervention when these are present in bipolar disorder could result in significant health and economic benefits.