Associations Between Vitamin D Deficiency/Insufficiency and Depression Expose Health Disparities in Older Rural West Texans: A Project FRONTIER Study.

ABSTRACT

OBJECTIVE: To determine associations between Vitamin D (VD) levels and clinical depression through the Geriatric Depression Scale (GDS) and its questions and subdomains, stratified by demographics and Hispanic/Latino ethnicity (HLE). DESIGN, SETTING, AND PARTICIPANTS: A cohort of 299 Project FRONTIER participants aged 62.6 ± 11.7 years old, 70.9% female, and 40.5% HLE were used. Standard correlation and regression analyses were employed. MEASUREMENTS The main outcome measures were VD (serum 25(OH)-VD) level, GDS-30 (30-item questionnaire), GDS-30 subfactors and questions, and HLE status. VD categories were defined as VD deficiency (VDD; ≤20 ng/mL), VD insufficiency (VDI; 21-29 ng/mL), VD sufficiency (30-38 ng/mL) and high VD sufficiency (>38 ng/mL). RESULTS: The majority (61.5%) of samples fell into VDD/VDI categories. A significant negative association was found between VD level and GDS-30 total score. VD level was negatively correlated with Dysphoria and Meaninglessness GDS-30 subfactors. Although GDS subfactors were similar between HLE and non-HLE groups, VD levels were significantly lower in HLE samples. Finally, HLE/non-HLE groups were differentially stratified across VD categories. Only 4% of HLEs fell into the high VD sufficient category, suggesting low VD supplementation. CONCLUSION: A significant negative association between VD level and depressive symptoms was revealed in our aging Project FRONTIER participants. HLE individuals were overrepresented in VDD/VDI samples, and VDD/VDI was associated primarily with the Dysphoria GDS subdomain. Regression analysis predicted high VD sufficiency (95.5 ng/mL) to be associated with no depressive symptoms (GDS=0). Our results underscore troubling disparities in VD-related depressive symptoms between HLE and non-HLE populations.