CBS and Mental deterioration: The deficient 1, 25(OH)2D3 levels in schizophrenics results in an increase in homocysteine levels by blocking the activity of cystathionine β-synthase (CBS) and also inhibit NOS dependent NO production leading to cognitive decline (Malik, A. A et al., 2016), similar correlations of Vit D with homocysteine (r = 0.502) and NOS (r = 0.411).