Publication Date

2012-05-01

Availability

Open access

Embargo Period

2012-05-01

Degree Name

Master of Science (MS)

Department

Psychology (Arts and Sciences)

Date of Defense

2012-04-09

First Committee Member

Neil Schneiderman

Second Committee Member

Marc Gellman

Third Committee Member

Ronald Goldberg

Abstract

The association between depression and the Metabolic Syndrome (MetS) has been extensively investigated, and inflammation has been identified as an underlying link. Recent reports, however, indicate a possible role of leptin in modulating the immune response, yielding increases in inflammatory markers. The literature suggests this hormone may not only explain the metabolic abnormalities associated with depression but may also act as a biomarker of depression itself. This study aimed to determine the association between circulating leptin and total depressive symptoms and depressive symptom dimensions (cognitive and somatic) after controlling for important confounding factors such as age, gender, insulin resistance, body mass index (BMI) and inflammation. We studied 119 Hispanic participants, 60 women and 59 men, recruited for the Community Health and Risk-reduction for the Metabolic Syndrome (CHARMS) study. Depression was measured using the Beck Depression Inventory (BDI). Somatic and Cognitive subscale scores were calculated. Leptin was measured using a leptin-specific enzyme immunoassay. Inflammation was assessed using C-reactive protein (CRP) measured with a high-sensitivity assay. Participants with CRP levels greater than 10 mg/L were excluded from analysis. CRP and leptin levels were log transformed to achieve a normal distribution. Median BDI total score, BDI cognitive score and BDI somatic score were 8, 3 and 5, respectively. Median circulating leptin levels were 30.6 ng/ml. In univariate regression, leptin levels were significantly associated with total (β =0.36, P=.000), cognitive (β =0.24, P=.011) and somatic depressive symptoms (β =0.48, P=.000). After controlling for age, gender, insulin resistance, BMI and inflammation, circulating leptin levels remained significantly associated with somatic depressive symptoms only (β =.41, P=.004). Another important predictor of somatic depressive symptoms was age (β=0.23; P=0.004). The model accounted for 31% of the variance in somatic depression scores. Leptin is significantly associated with somatic depressive symptoms in Hispanics with the MetS. This association was independent of important confounding factors such as gender, age, BMI, insulin resistance and inflammation. Further research is needed to elucidate the complex pathways linking depression and the MetS while incorporating the potential role of leptin.

Keywords

leptin; depression; inflammation; Hispanics; Metabolic Syndrome

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