Potential role of vitamin D3 in preventing neurocognitive complications in COVID-19 survivors

The common neurocognitive deficits among the COVID-19 survivors are confusion, altered sensorium, and memory deficits, which may be seen during the COVID-19 infection to long after recovery from the infection.1,2 Various factors (hypoxia, inflammation, immune activation, toxic damage, and neuro-invasiveness of the virus) due to the COVID-19 infection possibly attribute to brain damage and subsequent neurocognitive deficits, of which inflammatory/immune-mediated damage is a prominent one.3,4 Evidence support inflammatory mediators like interleukin-6 (IL-6) as an essential moderator of neuropsychiatric complications among COVID-19 survivors in the long term.3 Several inflammatory mediators, including IL-6, tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), are found to be elevated during COVID-19 infection, and their levels are very much increased during the cytokine storm that gives rise to severe form of COVID.4 The inflammatory mediators (IL-6 and TNF-α) cause microglial activation after crossing the blood–brain barrier, which stimulates the production of IL-1β.4 The IL-1β has a propensity for the hippocampal neurons, and it disrupts the cognitive processing (long-term potentiation) at the hippocampus, which is responsible for the memory difficulties, impairment of attention.4 Vitamin D3 is known to suppress the activity of these inflammatory mediators, and the level of vitamin D3 is found to be low in patients with COVID-19 infection.4 Therefore, vitamin D3 deficiency can attribute to neurocognitive deficits in patients with COVID-19 infection. [...]any preventive measure that prevents the hastening of neurodegeneration is likely to protect the neurocognitive functioning. In this regard, positive health measures like exposure to sunlight (that helps in the synthesis of vitamin D), increasing diet rich in vitamin D, and supplementation of vitamin D may reduce the risk of cytokine storm and COVID severity.