Major depressive disorder (MDD) affects approximately 16.6% of U.S. adults in their lifetimes and bipolar disorder has a lifetime prevalence of 2.1% in U.S. adults [1, 2]. Both MDD and bipolar disorder are marked by high rates of medical and psychological comorbid conditions as well as functional impairment [2–5]. At least 64.1% of patients with MDD have another comorbid psychiatric diagnosis, and primary care patients who have MDD have also reported an average of two to three concurrent chronic medical illnesses, which is approximately double those without depression [4, 5]. Similarly, in a national epidemiological study, Merikangas and colleagues found that 92.3% of bipolar individuals have a comorbid psychiatric diagnosis and 58.8% have a comorbid medical diagnosis [2]. More specifically, Forty and colleagues found that the most prevalent comorbid medical conditions of MDD and bipolar disorder are: migraines, asthma, elevated lipids, hypertension, thyroid disease and osteoarthritis [6]. Individuals with MDD and bipolar disorder also have a higher incidence of cardiovascular disease, diabetes, and metabolic syndromes, due in part to less engagement in physical activity and more sedentary behavior as well
