ASSOCIATION BETWEEN VITAMIN D STATUS AND DEPRESSION IN MALE TWINS. Open Access

Gavrilyuk, Andrey V. (2016)

Permanent URL: https://etd.library.emory.edu/concern/etds/mp48sd017?locale=en
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Abstract

Background: Depression and vitamin D deficiency are two major global health problems. To date it is still not clear if vitamin D deficiency plays a role in the rising incidence of major depression. Observational studies and randomized clinical trials have provided no definitive answer due to conflicting results.

Objective: To examine the relationship between vitamin D status and a clinical diagnosis of major depression, adjusting for potential confounding factors.

Design: We studied 509 middle-aged male twins, including 153 pairs and 5 unpaired monozygotic (MZ) and 97 pairs and 4 unpaired dizygotic (DZ) twins from the Vietnam War Era Twin Registry, who underwent a clinical interview for the assessment of major depression (lifetime history) and measurement of serum vitamin D[25(OH)]. Vitamin D levels were classified according to accepted clinical categories: deficient(<30 ng/mL), insufficient (30-49 ng/mL), and sufficient/optimal (50-80 ng/mL). We used generalized estimating equations (GEE) to test the association between vitamin D level as a continuous variable , as well as vitamin D clinical categories, with major depression.

Results: When vitamin D was treated as continuous variable, the odds of depression were 26% lower per incremental ng/mL of vitamin D, but the association was not significant (odds ratio [OR]=0.74; 95% confidence interval [CI]:0.51-1.10). After adjusting for age, physical activity, alcohol use and BMI, the estimate remained similar (OR=0.78, 95% CI: 0.53-1.16). When clinical categories of vitamin D were compared, using the sufficient/optimal category as reference, the odds of depression in the deficient category were significantly higher (OR=1.72, 95% CI: 1.01-2.95), while the odds in the insufficient category were similar (OR=1.18, 95% CI=0.69-2.02) compared with the sufficient category. The association was slightly attenuated after adjustment for age, BMI, physical activity, and alcohol consumption (OR=1.65, 95% CI: 0.95-2.84, comparing vitamin D deficiency to sufficiency). There was no significant association within either MZ or DZ twin pairs, and the interaction with zygosity was not significant. Conclusion: Although there is a cross-sectional association between clinical categories of vitamin D and depression, such association is in part explained by other lifestyle factors and possibly by familial factors shared by the twins.

Table of Contents

I. Introduction....................page 1.

II. Subjects and methods......page 5.

III. Results ..........................page 10.

IV. Discussion......................page 13.

V. Future directions.............page 16.

VI. Tables and figures............page 18.

VII. References ....................page 23.

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