Vitamin D deficiency may increase the risk of developing cognitive impairment especially for APOE e4 non‐carriers

Abstract

AbstractBackgroundVitamin D has been reported to play a role for neural protection and anti‐inflammation. However, its effects on the risk of cognitive decline has been inconsistent. Apolipoprotein E (APOE) could be a possible modulator of such influences as it takes part in the transport of cholesterol sharing a synthetic pathway with vitamin D and APOE e4 isoform is a well‐known significant risk factor of cognitive impairment. This study aimed to demonstrate the effects of vitamin D on incident cognitive impairment including mild cognitive impairment (MCI) and dementia and to explore its associations according to APOE e4 allele presence.MethodWe enrolled 1,271 cognitively normal community‐dwelling adults aged 60 years or older from the participants in the Korean Longitudinal Study on Cognitive Aging and Dementia. They were evaluated every two years from 2010 to 2018. We measured serum 25‐hydroxyvitamin D [25(OH)D] level and administered diagnostic assessment on MCI and dementia at every evaluation. We grouped the serum 25(OH)D into three levels as sufficient (> 30 ng/mL), insufficient (20 – 29.9 ng/mL), and deficient (< 20 ng/mL). We examined the associations of serum 25(OH)D level with the risks of incident MCI and dementia using Cox proportional hazard models adjusting for potential confounders. Then we also analyzed these effects in the APOE e4 non‐carriers and carriers separately.Result221 subjects showed a progression to MCI or dementia while 1,050 remained unchanged or improved cognitive function during follow‐up period. Participants who had deficient vitamin D concentration showed significant associations with a higher risk of cognitive decline (HR = 2.945, 95% CI = 1.088 – 7.970, p = 0.033) compared to sufficient 25(OH)D level group. APOE e4 non‐carriers who were vitamin D deficiency at baseline were 3.3‐fold more likely to suffer progression of cognitive impairment (HR = 3.308, 95% CI = 1.050 – 10.426, p = 0.041), whereas APOE e4 carriers did not show significant correlations of 25(OH)D levels with such progression (p > 0.05).ConclusionThese results indicate that vitamin D deficiency may increase the risk of developing cognitive impairment and the effects would be greater for APOE e4 non‐carriers compared to APOE e4 carriers.