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Vitamin B12, cobalamin, mood, mental health, cognitive functions, elderly


Decline in cognitive and motor functions and in mental health are commonly seen with aging. Although many reports attribute their etiology to aging, these conditions may have vitamin B12 deficiency as an underlying mechanism. Laboratory tests to assess vitamin B12 deficiency lack sensitivity and specificity largely due to absence of a gold standard for diagnosis. Additionally, patients with subclinical vitamin B12 deficiency have typically normal serum concentration levels and do not exhibit the classical symptoms of vitamin B12 deficiency. Furthermore, many comorbidities that exist with aging decrease vitamin B12 and bioavailaibility from the gut. If left untreated, vitamin B12 deficiency leads to irreversible nerve damage and brain atrophy which may result in mood alteration and cognitive decline. Microstructural changes in the myelin sheath have been described to alter the central nervous function. Additionally, elevated levels of serum homocysteine and epigenetic modifications have been documented with vitamin B12 deficiency. However, due to lack of vitamin B12 test sensitivity, many reports in the literature have failed to report a link between vitamin B12 deficiency and cognitive and mental health decline in elderly. The review suggests that there is a need to re-evaluate the role of vitamin B12 in these functions, especially in patients with comorbidities. Standardization of vitamin B12 testing across studies is needed to provide a better consensus of the actual role of vitamin B12 on cognitive function and mental health across populations.



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