Abstract
Objective: To examine vitamin D levels in major depressive disorder (MDD) subjects and investigate the relationship between MDD symptom severity and serum levels of this vitamin.
Methodology: The study was conducted in a tertiary care teaching hospital of a private medical college in Islamabad from March 2021 to December 2021. Forty patients with MDD, single episode or recurrent were included along with similar number of matched healthy controls. In order to assess the severity of depression, the Hamilton Rating Scale for Depression (HRSD) was employed. Serum vitamin D levels of cases and controls were compared.
Results: In the MDD group, HRSD score was 24±9.6 and the illness duration was 6±2.5 months. Mean level of Vitamin D was 18.4 ng/ml in the MDD group versus 30.6 ng/ml in healthy controls (p<0.001). Serum vitamin D levels were negatively correlated (p<0.001) with the severity of depression as measured by HRSD. There was no correlation between serum vitamin D levels and MDD illness duration (p>0.05).
Conclusion: The study findings suggested a relationship between MDD and serum vitamin D levels. However, further studies were needed in larger samples and at other geographic locations, controlling for exposure to sunlight and other variables.

Key words: Vitamin D, major depressive disorder, neurogenesis, oxidative stress, inflammation.