Study the Association Between Serum Vitamin D Level in Patients with Major Depressive Disorder

Abstract

epression is a chronic condition impairing all aspects of human function and affecting more than 300 million people worldwide (WHO, 2017). It is a major cause of illness burden to societies worldwide, with increasing effects on personal suffering, work disability, and use of healthcare resources (Wittchen et al., 2011). The pathophysiology of depression involves multiple interacting risk factors, covering biological, psychological and psychosocial factors (Kendler et al., 2006). Treatments for depression include a range of psychological therapies and antidepressant medications with main goal of complete relief of symptoms, which is associated with better functioning and a lower likelihood of relapse. Electroconvulsive therapy is sometimes used in severe depression that has not responded to other treatments (NICE, 2017). Vitamin D is a steroid hormone provided from natural synthesis in the skin and from dietary sources (Spiro & Buttriss, 2014). Vitamin D has diverse biological skeletal and non-skeletal functions through the binding of the biologically active metabolite; 1,25(OH)2D to VDR in target tissues to regulate gene transcription (Szodoray et al., 2008). It may have an important role in the development of depression. VDRs are present on neurons and glia in many areas of the brain including the cingulate cortex and hippocampus, which have been implicated in the pathophysiology of depression. Vitamin D is also involved in numerous brain processes including neuroimmunomodulation, regulation of neurotrophic factors, neuroprotection, neuroplasticity and brain development making it biologically plausible that this vitamin might be associated with depression (Fernandes et al., 2009). The association between low serum levels of vitamin D and depression could be explained by the following biological mechanisms: