What Role Does Vitamin D Deficiency Play in Depression? A Small Case Study Report

Thanks to basic science, we know that there are vitamin D receptors in the brain.  Of particular interest to this vitamin D and depression study, there are vitamin D receptors in the amygdale/limbic system, which is responsible for regulating behavior and emotion.

The exact relationship between vitamin D and depression is not understood, however, and the few randomized controlled trials on this have hinted at a causal relationship.

Research presented at the 94th Annual Meeting of The Endocrine Society examined if vitamin D replacement in vitamin D deficient patients with major depressive disorder would have an effect on depressive symptoms.  Lead author Sonal Pathak, MD, study author, said, “Vitamin D may have an as-yet-unproven effect on mood, and its deficiency may exacerbate depression.  If this association is confirmed, it may improve how we treat depression.”

This study (called “Vitamin D Deficiency [VDD] and Major Depressive Disorder [MDD]: A Causal or Casual Association?”) was a small case study—there were 3 patients involved, all of whom had been diagnosed with MDD.¹

They were all at risk for vitamin D deficiency (based on low vitamin D intake and low sun exposure) and were tested for vitamin D levels using a 25-hydroxyvitamin D blood test.

Over 8 to 12 weeks, the women were treated to vitamin D repletion and their depressive symptoms re-evaluated at that time.

Individual case results are presented below.

Patient 1
Patient 1 was 42 years old.  She was hypothyroid and was treated with L-T4 with TSH 1.24 µlU/mL (0.45-4.50).

On the Beck Depression Inventory Scale (BDI), her score was 32.  (30-63 is considered severe depression.)

Her vitamin D level at presentation was 12 ng/mL.  Levels less than 21 ng/mL are representative of vitamin D deficiency.

Patient 1 was treated with vitamin D replacement therapy, and her BDI after treatment was 12, representing mild depression.

Patient 2
Patient 2 was 58 years old, and she had type 2 diabetes.

Her presenting BDI was 26, and her vitamin D level was 8.9 ng/mL.

After vitamin D replacement, Patient 2’s BDI was 8, which falls into the minimal depression range.

Patient 3
Patient 3 was 66 years old, and she also had type 2 diabetes.

At presentation, her BDI was 21; her vitamin D level was 14.5 ng/mL.

Following vitamin D replacement, her BDI was 16 (mild depression).

Should All Depressed Patients Be Tested for Vitamin D Deficiency?
More research is, of course, needed to support these findings, but this small case study does suggest that screening patients with major depressive disorder for vitamin D deficiency may provide a cost-effective addition to traditional depression treatment.