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A Prospective Observational Study of Obesity, Body Composition, and Insulin Resistance in 18 Women With Bipolar Disorder and 17 Matched Control SubjectsSara B. Fleet-Michaliszyn, Ph.D.; Isabella Soreca, M.D.; Amy D. Otto, Ph.D., R.D.; John M. Jakicic, Ph.D.; Andrea Fagiolini, M.D.; David J. Kupfer, M.D.; and Bret H. Goodpaster, Ph.D.Objective: Patients with bipolar disorder are at increased risk for diabetes and cardiovascular diseases, possibly because of more severe insulin resistance. The primary purpose of this study was to determine whether insulin resistance is characteristic of bipolar disorder. Method: The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was performed in 18 women with DSM-IV bipolar I disorder, and results were compared to those of 17 matched controls. Other risk factors were compared, including blood pressure, blood lipids, and abdominal obesity by computed tomography (CT). Additionally, substrate utilization was measured by indirect calorimetry, and free-living energy expenditure was estimated using wearable activity monitors. All data were collected between February 2006 and December 2007. Results: Patients with bipolar disorder were no more insulin resistant than controls after accounting for generalized obesity (mean ± SEM HOMA-IR = 2.7 ± 0.7 vs. 2.5 ± 0.7, for patients and controls, respectively; p = .79). Although blood lipid profiles were generally similar in patients and controls, obese patients had higher blood pressure than controls. Obese patients had more mean ± SEM total abdominal fat (718.1 ± 35.1 cm2 vs. 607.4 ± 33.6 cm2; p = .04), and tended (p = .06) to have more visceral abdominal fat. Patients oxidized 13% less fat during resting conditions, although their resting metabolic rate was similar to that of controls. Conclusion: Women with bipolar I disorder were no more insulin resistant than matched controls after accounting for their level of obesity. However, they were more hypertensive, had higher amounts of abdominal obesity, and had reduced rates of fat oxidation. Therefore, women with bipolar I disorder may be at a heightened risk for future weight gain and concomitant risk for diabetes and cardiovascular disease. (J Clin Psychiatry 2008;69:1892-1900. Online Ahead of Print October 21, 2008.) Received Jan. 11, 2008; accepted March 28, 2008. From the College of Nursing, University of Arizona, Tucson (Dr. Fleet-Michaliszyn) and the Department of Psychiatry (Drs. Soreca, Fagiolini, and Kupfer), the Department of Health and Physical Activity (Drs. Otto and Jakicic), and the Department of Medicine (Dr. Goodpaster), University of Pittsburgh, Pa. This project was supported by a grant from the School of Education (Dr. Fleet-Michaliszyn) and by the Obesity and Nutrition Research Center (1P30DK46204) and Clinical and Translational Research Center(5 M01RR00056) at the University of Pittsburgh. The authors thank the volunteers for their participation. Dr. Jakicic has received grant/research support from the Beverage Institute for Health and Wellness and has been a member of the speakers/advisory boards for the Beverage Institute for Health and Wellness, BodyMedia, and the Calorie Control Council. Dr. Fagiolini has served as a consultant to and been a member of the speakers/advisory boards for Bristol-Myers Squibb and Pfizer. Dr. Kupfer's spouse has received grant/research support from the National Institute of Mental Health, Forest, and the Fine Foundation; has received honoraria from Lundbeck; has been a member of the advisory board for Servier; and has received royalties from Guilford Press. Drs. Fleet-Michaliszyn, Soreca, Otto, and Goodpaster report no additional financial or other relationship relevant to the subject of this article. Corresponding author and reprints: Bret H. Goodpaster, Ph.D., Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15233 (e-mail: bgood@pitt.edu). |