Depression: Can vitamin D alleviate symptoms of depression not cured by antidepressants as well as alleviate negative skeletal effects caused by antidepressants?

Use of antidepressants is associated with an increased risk of fractures, and may be a result of both negative effects on the skeleton as well as increased risk of falling; however, the specific mechanisms are not yet known. Vitamin D play important roles for bone and muscle, and has previously shown positive effects in lowering the risk of osteoporosis and risk of falling. In addition, vitamin D may improve mental health, and deficiency of vitamin D is a common condition among patients suffering from depression.

This thesis investigates bone and factors related to fall risk (including muscle function, muscle pain, mobility, and balance) among patients taking antidepressants, and study the effect of vitamin D3 treatment over placebo. The thesis is based on a clinical cross-sectional study and a randomised double-blind placebo-controlled trial of women treated with antidepressants and healthy controls.

Certain balance measures were poorer among the patients compared to the controls and was associated with the dose of the antidepressant. Patients randomised to vitamin D3 increased more in vitamin D and decreased more in PTH levels compared to vitamin D3 treated controls. Moreover, vitamin D3 reduced muscle pain threshold levels for certain pain measures and improved muscle strength only among the patients. Further, vitamin D3 was associated with improvements in depressive symptoms in both groups.