Serum retinol levels are associated with cognitive function among community-dwelling older Mexican adults.

Background: Vitamin A (VA) provides neuroprotection against oxidative stress and brain inflammation. VA deficiency (VAD) increases the risk of neurodegeneration in animal models, but results are inconclusive in humans: particularly in the older adult (OA) population which is at higher risk for micronutrient deficiencies and cognitive impairment.

Objective: To estimate the association between serum retinol levels and cognitive function (CF) in older Mexican adults.

Methods: Cross-sectional study with 803 adults aged ≥60 years with fasting blood sample from the southern region of Mexico, collected in summer of 2015. Low serum retinol (LSR) was defined if serum retinol ≤20 µg/dl. CF was evaluated using Semantic Verbal Fluency Test (SVFT). Mild cognitive impairment (MCI) was defined using normative values for SVFT. Linear and logistic regression models were used to estimate the association of LSR with CF and MCI, respectively.

Results: Prevalence of MCI was 9.35% and LSR 3.36%. OA with LSR evoked less words in the SVFT (= -2.8, CI95% -4.6, -0.9) and had higher probability of MCI (OR =  2.7, CI95% 0.9, 7.7). Associations remained significant when considered IL-6.

Conclusion: Frequency of LSR in older Mexican adults was low, but strongly associated with MCI. This result suggests that VA plays a role in maintaining CF in the elderly population. Since VAD is a reversible condition, further studies are needed in order to identify the main causes of LSR and prevent MCI in populations which are at higher risk for malnutrition. ClinicalTrials.gov identifier: NCT04820465.