Vitamin D and cognition in Hispanic patients

Introduction: Recent research has shown an association between vitamin D deficiency and cognitive functioning. There is also evidence to suggest that there may be a relationship between low levels of vitamin D and Alzheimer’s disease. A review revealed there was minimal research on low vitamin D levels in minorities, particularly in Hispanics. This issue is particularly salient to Hispanics as they are the fastest growing aging population in the US. Additionally, the cost of Alzheimer’s disease to the US is estimated to be $226 billion in 2015, and Hispanics and African American make up the highest racial population with the disease. Methods: A literature review used search terms including vitamin d deficiency, cognition, Alzheimer’s, Hispanics, and Mexican-American, resulting in approximately 100 abstracts. Results: The articles reviewed demonstrated strong evidence of the relationship between a vitamin D deficiency and cognition. They also revealed an increased risk of Alzheimer’s disease (AD) and other types of dementia in the context of a low vitamin D level. Interestingly, AD is a disorder of progressive memory loss and cognitive dysfunction, but in those few studies that performed cognitive testing, a low vitamin D level correlated with poor executive functioning. Memory testing has yielded equivocal results. These studies used white participants and may not therefore reflect the general population. A multiethnic cohort study showed the mean vitamin D level of the sample as 19.2 (11.7) ng/mL, with 26.2% of participants being vitamin D deficient, and 35.1% insufficient. The mean serum vitamin D levels were lower for African-American and Hispanic participants compared with white participants. Various reasons for these differences have been hypothesized including cultural differences in vitamin D intake, incidence of renal insufficiency, place of birth, and less vitamin D production due to more highly pigmented skin. Conclusion : Hispanics are the fastest growing ethnic population in the US and have higher rates of obesity, liver disease, tobacco use, heart disease, diabetes, metabolic disorder, stroke, and hypertension. Many of these disorders are related to vitamin D, and all are associated with cognitive deficits. It is unknown at this time if vitamin D supplementation will reverse cognitive deficits. Therefore, it is important to add Hispanic cohorts to future studies to explore the relationship between vitamin D and cognition.