The Association Between Vitamin D Status and Depression Severity in Adults with Major Depressive Disorder: A Cross-Sectional Study

Abstract

The implication of vitamin D in the pathophysiology of depression has generated interest regarding its role as a biomarker in the context of mental health. Given the limited data on this association in the Romanian population, the present study aimed to evaluate the correlation between vitamin D status and the severity of depressive symptomatology in a sample of adult patients from Romania. This cross-sectional study was conducted on 90 patients diagnosed with major depressive disorder who were admitted to the Department of Psychiatry at the County Clinical Emergency Hospital of Bihor during the period of 2024–2025. Serum vitamin D concentrations were determined by measuring the 25-hydroxyvitamin D metabolite in blood using the chemiluminescence microparticle immunoassay method. The severity of depressive symptomatology was quantified using two validated scales: the Beck Depression Inventory-II (BDI-II) and the Hamilton Depression Rating Scale 17 (HAM-D17). Multivariable linear regression and ordered probit regression were used to assess the relationship between vitamin D status and depression severity, with adjustments for relevant covariates. A statistically significant negative association was identified for the BDI-II scale (B = −0.3170444, β = −0.2621328, p = 0.007) and the HAM-D17 scale (B = −0.1495026, β = −0.2829461, p = 0.002), which remained robust after adjustment for covariates (BDI-II: B = −0.2110473, β = −0.1744942, p = 0.050; HAMD17: B = −0.1153659, β = −0.2183397, p = 0.018). In comparison with subjects with vitamin D deficiency, those with sufficient levels presented a significantly lower probability of belonging to higher severity categories of depression for both scales (BDI-II: coefficient = −0.6855429, p = 0.004; HAM-D17: coefficient = −0.7029572, p = 0.005). The study highlighted a statistically significant negative correlation between vitamin D status and depression severity, which remained after adjustment for covariates. Sufficient vitamin D levels were associated with a significantly lower probability of belonging to a higher depression severity category compared with deficiency.