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Arterial damage and cognitive impairment in patients with chronic kidney disease

Dear Editor, I read with great interest the recent publication by Karasavvidou and colleagues1 entitled “Arterial damage and cognitive decline in chronic kidney disease patients.” The authors conducted a cross‐sectional study to know the association between artery stiffness, microvascu‐ lar damage, and cognitive impairment in patients with chronic kidney disease (CKD). Arterial stiffness was assessed by carotid‐femoral pulse wave velocity (cf‐PWV). High values of cf‐PWV and aortic pulse pres‐ sure were independent determinants of cognitive impairment, and there were interactions among the kidney function, large artery dam‐ age, central pressure pulsatility, and the injury of brain microcircula‐ tion. The stage of CKD progresses by aging in their study, and I have two concerns with special reference to frailty by aging. First, Coppolino and colleagues2 assessed the relationship between kidney function and cognitive ability among elderly frail individuals. In multiple regression analysis, cognitive ability was significantly associ‐ ated with estimated glomerular filtration rate (eGFR). In addition, they speculated the combination effect of kidney and cognitive dysfunc‐ tion on adverse health outcome. Furtado and colleagues3 conducted a meta‐analysis on the association between frail progression and cog‐ nitive status in populations older than 60 years of age. Significant de‐ crease in mean values of the Mini‐Mental State Examination score was found in prefrail and frail subgroups against nonfrail subgroup, and the progression of cognitive dysfunction was observed as the level of frailty advanced. Inter‐relationship among several levels of arterial damage, kid‐ ney function, and frailty should be used for predicting cognitive decline. Second, Chowdhury and colleagues4 conducted a systematic re‐ view to evaluate the association between CKD, frailty, and adverse health outcomes across different stages of renal impairment. The incidence of frailty increased with reduced eGFR, and frailty was associated with an increased risk of mortality and hospitalization. Although Karasavvidou and colleagues could not evaluate patients having fatal risk, advanced stage of arterial damage or end‐stage renal disease (ESRD) would be closely related to cognitive decline. Relating to ESRD, Kallenberg and colleagues5 conducted a system‐ atic review and reported a significant association of functional or cognitive impairment or frailty with mortality in patients with ESRD. Recently, there is also a report that arterial stiffness is closely related to cognitive impairment, and arterial stiffness severity can be used to predict the onset and progression of dementia in elderly individuals.6 In addition, prefrailty and frailty are signifi‐ cantly associated with higher arterial stiffness in older adults.7 Taken together, comprehensive study would be required for pre‐ dicting cognitive decline in patients with CKD, arterial damage, and frailty.