Obesity in patients with bipolar disorder: a biopsychosocial-behavioral model.

OBJECTIVE: We provide a model to explicate how factors representing different levels of analysis (i.e., biology, psychology, sociodemographics, and behavior) interact to influence the onset and maintenance of obesity in bipolar disorder. DATA SOURCES: We conducted MEDLINE (1966-2005) and PsycInfo (1872-2005) searches of all English-language articles using the keywords obesity, body weight, weight gain, and metabolic syndrome combined with bipolar disorder, depression, atypical depression, binge eating, and pharmacotherapy. STUDY SELECTION: Studies were selected if they provided data regarding (1) the prevalence of obesity in patients with bipolar disorder, (2) correlates of obesity in patients with bipolar disorder, or (3) evidence that a clinical feature(s) or correlate(s) of bipolar disorder is associated with obesity. Ninety-two studies were reviewed. DATA SYNTHESIS: Obesity is prevalent in patients with bipolar disorder and is associated with increased medical morbidity and poorer psychiatric outcome. Variables that may interact to influence the onset and maintenance of obesity in bipolar disorder include genetic factors, neurotransmitter abnormalities, atypical depression, eating behaviors, pharmacotherapy, age, gender, socioeconomic status, and physical inactivity.
CONCLUSIONS: Although the exact causes of obesity in bipolar disorder undoubtedly vary across patients, the etiologic cascade, which includes biological, psychological, and sociodemographic variables, ultimately directly or indirectly affects levels of physical activity and eating behavior, leading to obesity in this population. Behavioral interventions aimed at targeting physical inactivity and overeating in bipolar disorder patients are needed, as are better screening and treatment for binge eating. Finally, there is a clear need for ongoing research to explicate the causes and consequences of obesity across levels of analysis.