Are psychological characteristics related to risk of the metabolic syndrome? A review of the literature

Background: We evaluate the evidence that depression, anger, hostility, and anxiety are related to risk for the metabolic syndrome, focusing as well on its components of central adiposity and insulin resistance. In addition, we identify possible moderators of these associations and summarize plausible underlying biobehavioral pathways. Methods: Medline, PsycINFO, PubMed, and Web of Science searches were conducted using the keywords metabolic syndrome, syndrome x, central adiposity/obesity, visceral adiposity/obesity, body fat distribution, waist circumference, waist hip ratio, insulin resistance/sensitivity, glucose tolerance, psychological, depression, hostility, anger, cynicism, and anxiety. Results: The current literature provides cross-sectional evidence for an association between psychological characteristics and the metabolic syndrome. Prospective data, though limited, suggest that depression, hostility, and anger predict increased risk for the metabolic syndrome. Data on modifiers are too limited to permit definitive conclusions. Negative health behaviors and hypothalamic and sympathetic dysregulation are identified as plausible underlying pathways. Conclusions: More prospective studies, conducted with diverse samples, are needed to delineate the direction of this relationship and the proposed biobehavioral mechanisms; experimental investigations are needed to test for causality. Nevertheless, findings suggest that psychological characteristics, especially depression, hostility, and anger, may increase risk for the metabolic syndrome, providing a novel direction for prevention and treatment interventions.