**11. Conclusion**

To summarize, vitamin D deficiency is associated with several types of mood disorders involving various molecular and genetic mechanisms related to vitamin D receptors and VDR gene. The VDR gene mutation alters vitamin D binding capacity to vitamin D receptor, preventing vitamin D activation into calcitriol which regulates synthesis of neurotrophic factors. Failing to maintain these neurotrophic factors in the presence of vitamin D deficiency leads to cerebral dysfunction and thereby contributes to mood disorder symptoms. Further, vitamin D deficiency is also associated with cognitive reasoning and mind disturbance that trigger off mood disorders like major depressive disorders, seasonal affective disorder, suicidal tendency, postpartum depression to the childbearing mothers, premenstrual syndrome to the ladies on the onset of their menses, ADHD, schizophrenia, and aging depressive symptoms. Futures studies and clinical trials can also be structured to establish a better understanding of the effects of the vitamin D deficiency on several mood disorders, behavioral disorders, and cognition.
