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Obesity, Body Composition and Insulin Resistance in Women with and without Bipolar Disorder

Fleet, Sara Beth (2007) Obesity, Body Composition and Insulin Resistance in Women with and without Bipolar Disorder. Doctoral Dissertation, University of Pittsburgh.

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    Abstract

    Obesity and cardiovascular disease is common in bipolar disorder, both of which are associated with insulin resistance. Insulin resistance is also associated with distribution of body fat, specifically abdominal visceral fat and fat accumulation in skeletal muscle. Furthermore, reduced capacity to utilize fat has been linked with obesity, type 2 diabetes and insulin resistance. PURPOSE: To compare insulin sensitivity, body composition and resting substrate utilization between obese and normal weight patients with bipolar 1 disorder and race, age and BMI matched controls. METHODS: Participants underwent dual energy X-ray absorptiometry (DEXA) to measure fat mass (FM) and fat-free mass (FFM), computed tomography (CT) to measure cross-sectional abdominal adipose tissue and indirect calorimetry to measure resting substrate oxidation. Free- living energy expenditure was measured for 5 days using BodyMedia SenseWear Pro Armband and the food frequency questionnaire estimated the usual consumption of 79 main food items over the preceding 12 months. Insulin sensitivity was measured from fasting insulin and glucose measurements and defined by the homeostatic model assessment of insulin resistance (HOMA IR). RESULTS: Eighteen patients with bipolar 1 disorder and 17 controls participated in this study. There were no differences observed in insulin resistance between obese (BMI > 30 kg/m2) patients and controls (56.8 ± 17.2 vs. 51.8 ± 11.1; P = 0.842) or normal weight (BMI < 25 kg/m2) patients and controls (30.5 &plusmn 6.3 vs. 27.0 ± 5.7 P = 0.691). CT revealed a difference in total abdominal fat (718.1 &plusmn 33.6 vs. 607.4 ± 38.6cm2; P = 0.04), a trend in visceral abdominal fat (P = 0.06) though no difference in subcutaneous abdominal fat between obese patients and controls. Indirect calorimetry revealed a trend (P=0.06) in reduced fat oxidation in normal weight patients compared to controls and when combining obese and normal weight patients. CONCLUSION: Patients with bipolar 1 disorder do not appear to be more insulin resistant than controls after accounting for their obesity. However, a reduced fat oxidation in normal weight patients may be an underlying factor predisposing them for future weight gain and concomitant increased risk for type 2 diabetes.


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    Item Type: University of Pittsburgh ETD
    ETD Committee:
    ETD Committee TypeCommittee MemberEmailORCID
    Committee ChairGoodpaster, Bret HBgood@pitt.edu
    Committee MemberOtto, AmyAyotto@pitt.edu
    Committee MemberFagiolini, AndreasFagiolinia@upmc.edu
    Committee MemberKupfer, DavidKupferdj@upmc.edu
    Committee MemberJakicic, John JJjakicic@pitt.edu
    Title: Obesity, Body Composition and Insulin Resistance in Women with and without Bipolar Disorder
    Status: Unpublished
    Abstract: Obesity and cardiovascular disease is common in bipolar disorder, both of which are associated with insulin resistance. Insulin resistance is also associated with distribution of body fat, specifically abdominal visceral fat and fat accumulation in skeletal muscle. Furthermore, reduced capacity to utilize fat has been linked with obesity, type 2 diabetes and insulin resistance. PURPOSE: To compare insulin sensitivity, body composition and resting substrate utilization between obese and normal weight patients with bipolar 1 disorder and race, age and BMI matched controls. METHODS: Participants underwent dual energy X-ray absorptiometry (DEXA) to measure fat mass (FM) and fat-free mass (FFM), computed tomography (CT) to measure cross-sectional abdominal adipose tissue and indirect calorimetry to measure resting substrate oxidation. Free- living energy expenditure was measured for 5 days using BodyMedia SenseWear Pro Armband and the food frequency questionnaire estimated the usual consumption of 79 main food items over the preceding 12 months. Insulin sensitivity was measured from fasting insulin and glucose measurements and defined by the homeostatic model assessment of insulin resistance (HOMA IR). RESULTS: Eighteen patients with bipolar 1 disorder and 17 controls participated in this study. There were no differences observed in insulin resistance between obese (BMI > 30 kg/m2) patients and controls (56.8 ± 17.2 vs. 51.8 ± 11.1; P = 0.842) or normal weight (BMI < 25 kg/m2) patients and controls (30.5 &plusmn 6.3 vs. 27.0 ± 5.7 P = 0.691). CT revealed a difference in total abdominal fat (718.1 &plusmn 33.6 vs. 607.4 ± 38.6cm2; P = 0.04), a trend in visceral abdominal fat (P = 0.06) though no difference in subcutaneous abdominal fat between obese patients and controls. Indirect calorimetry revealed a trend (P=0.06) in reduced fat oxidation in normal weight patients compared to controls and when combining obese and normal weight patients. CONCLUSION: Patients with bipolar 1 disorder do not appear to be more insulin resistant than controls after accounting for their obesity. However, a reduced fat oxidation in normal weight patients may be an underlying factor predisposing them for future weight gain and concomitant increased risk for type 2 diabetes.
    Date: 30 January 2007
    Date Type: Completion
    Defense Date: 20 November 2006
    Approval Date: 30 January 2007
    Submission Date: 08 December 2006
    Access Restriction: No restriction; The work is available for access worldwide immediately.
    Patent pending: No
    Institution: University of Pittsburgh
    Thesis Type: Doctoral Dissertation
    Refereed: Yes
    Degree: PhD - Doctor of Philosophy
    URN: etd-12082006-105612
    Uncontrolled Keywords: ; abdominal obesity; bipolar disorder; body composition; depression; obesity; substrate metabolism
    Schools and Programs: School of Education > Health, Physical, Recreational Education
    Date Deposited: 10 Nov 2011 15:09
    Last Modified: 22 May 2012 12:39
    Other ID: http://etd.library.pitt.edu/ETD/available/etd-12082006-105612/, etd-12082006-105612

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