Role of Vitamin D in Cognitive Function in Chronic Kidney Disease

Abstract

Both vitamin D deficiency and cognitive impairment are common in patients with chronic kidney disease (CKD). Vitamin D exerts neuroprotective and regulatory roles in the central nervous system. Hypovitaminosis D has been associated with muscle weakness and bone loss, cardiovascular diseases (hypertension, diabetes and hyperlipidemia), inflammation, oxidative stress, immune suppression and neurocognitive impairment. The combination of hypovitaminosis D and CKD can be even more debilitating, as cognitive impairment can develop and progress through vitamin D-associated and CKD-dependent/independent processes, leading to significant morbidity and mortality. Although an increasingly recognized comorbidity in CKD, cognitive impairment remains underdiagnosed and often undermanaged. Given the association of cognitive decline and hypovitaminosis D and their deleterious effects in CKD patients, determination of vitamin D status and when appropriate, supplementation, in conjunction with neuropsychological screening, should be considered integral to the clinical care of the CKD population.

Keywords: chronic kidney disease; cognitive impairment; dialysis; hypovitaminosis D; vitamin D.

Figure 1

Risks of suboptimal vitamin D status in chronic kidney disease patients.

Figure 2

Suboptimal vitamin D status directly and indirectly contributes to the development and progression of cognitive impairment. Studies have demonstrated an association of hypovitaminosis D and diseases that raise vascular risks [85]. Endothelial dysfunction and inflammatory/uremic milieu in CKD act not only as a consequence of CKD but also through promoting vascular risk factors contributing the CKD progression.