Metabolic Comorbidity and Physical Health Implications for Bipolar Disorder: An Update

Medical comorbidities are overrepresented in individuals with bipolar disorder, including, but not limited to, cardiovascular conditions, autoimmune diseases, cancer, and metabolic disorders. Overweight/obesity, metabolic syndrome, and type 2 diabetes mellitus are highly prevalent in individuals with bipolar disorder. Evidence from epidemiological studies indicates that the aforementioned medical comorbidities are responsible for significant morbidity and early mortality. Results from disparate studies indicate that metabolic comorbidities modify and complicate the clinical presentation of bipolar disorder; metabolic comorbidities are associated with a more chronic and severe course of illness, as well as resistance to pharmacological treatment. Furthermore, co-occurrence of obesity or type 2 diabetes mellitus and bipolar disorder has been suggested to contribute to cognitive dysfunction, a core feature of bipolar disorder and a principal mediator of functional disability, highlighting the clinical relevance of this association. Multiple factors contribute to high frequency of metabolic comorbidities in individuals with bipolar disorder. An overlap of risk factors, including psychosocial stress, adverse socioeconomic conditions, and childhood trauma, between the two conditions has been documented. Inadequate diet and sedentary lifestyle, as well as treatment-emergent adverse effects have also been shown to play a role. Nonetheless, accumulating evidence indicates that the relationship between bipolar disorder and metabolic illnesses is bidirectional. Results from mechanistic studies indicate that interacting physiological systems that mediate metabolism are also involved in pathophysiological processes of bipolar disorder. The high prevalence and substantial impact of metabolic comorbidities on the clinical outcome in bipolar disorder underscore the need for prioritizing the management of metabolic health in this clinical population.