Vitamin K status and cognitive function in adults with chronic kidney disease: The Chronic Renal Insufficiency Cohort

Authors: SHEA, KYLA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; WANG, JIFAN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; BARGER, KATHRYN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; WEINER, DANIEL - Tufts Medical Center; BOOTH, SARAH - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; SELIGER, STEPHEN - University Of Maryland; ANDERSON, AMANDA - Tulane University; DEO, RAJAT - University Of Pennsylvania; FELDMAN, HAROLD - University Of Pennsylvania; GO, ALAN - University Of California San Francisco (UCSF); HE, JIANG - Tulane University; RICARDO, ANA - University Of Illinois; TAMURA, MANJULA - Va Palo Alto Health Care System (VAPAHCS)

Submitted to: Current Developments in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2022
Publication Date: 6/24/2022
Citation: Shea, K., Wang, J., Barger, K., Weiner, D.R., Booth, S.L., Seliger, S., Anderson, A.H., Deo, R., Feldman, H.I., Go, A., He, J., Ricardo, A.C., Tamura, M.K. 2022. Vitamin K status and cognitive function in adults with chronic kidney disease: The Chronic Renal Insufficiency Cohort. Current Developments in Nutrition. https://doi.org/10.1093/cdn/nzac111.
DOI: https://doi.org/10.1093/cdn/nzac111

Interpretive Summary: Motivated by previous studies linking vitamin K status to cognitive decline, we evaluated the association of vitamin K status biomarkers with cognitive performance in adults with chronic kidney disease (CKD), a group at heightened risk for cognitive decline and vitamin K insufficiency. Vitamin K status was estimated using two blood measures: phylloquinone concentrations and uncarboxylated matrix gla protein (ucMGP) concentrations. Phylloquinone is the primary form of vitamin K in blood. UcMGP is a measure of vitamin K function, and concentrations increase when vitamin K status is low. Participants with low plasma ucMGP, reflecting higher vitamin K status, had better overall cognitive performance based on a composite score of six separate tests. However, plasma phylloquinone was not associated with global cognitive performance. Neither biomarker was significantly associated with performance on any individual test. The importance of vitamin K to cognitive performance in adults with CKD remains to be clarified.

Technical Abstract: Vitamin K is linked to cognitive function, but studies in individuals with chronic kidney disease (CKD), who are at risk for both vitamin K insufficiency and cognitive impairment, are lacking. We evaluated the cross-sectional association of vitamin K status biomarkers with cognitive performance in >=55 year-old adults with CKD (n=714, 49% female, 44% Black). A composite score of a cognitive performance test battery, calculated by averaging the z-scores of the individual tests, was the primary outcome. Vitamin K status was measured using plasma phylloquinone and dephospho-uncarboxylated matrix gla protein ((dp)ucMGP). Participants with low plasma (dp)ucMGP, reflecting higher vitamin K status, had better cognitive performance based on the composite outcome (p=0.03), whereas it did not significantly differ according to plasma phylloquinone categories (p=0.08). Neither biomarker was significantly associated with performance on individual tests (all p>0.05). The importance of vitamin K to cognitive performance in adults with CKD remains to be clarified.