MP595THE CEREBROVASCULAR AND NEUROCOGNITIVE EFFECTS OF HAEMODIALYSIS

Abstract

INTRODUCTION AND AIMS: Stroke and cognitive impairment are common in the haemodialysis (HD) population. It is possible that HD induced alterations in the cerebral circulation contribute. We assessed cognitive function in HD patients to describe the frequency of occult cognitive impairment, and performed assessments both on & off dialysis to explore if changes in cerebral blood flow during HD affect cognitive function. METHODS: We performed a prospective cohort study in adult patients receiving HD for established renal failure (ERF). Those with known cerebrovascular or cognitive impairment were excluded. A detailed neurocognitive assessment was performed during a routine dialysis session and on a non-dialysis day (with a 4 week gap to reduce learning effect). Cognitive testing included use of the Montreal Cognitive Assessment (using an accepted cut-off to define cognitive impairment) and additional tests of language, memory, processing speed and executive function. Mean flow velocity (MFV) was measured in the middle cerebral artery during dialysis using Transcranial Doppler ultrasound. We compared cognitive function and MFV on and off dialysis and assessed the relationship between any changes using Spearman's rank correlation. RESULTS: 97 participants were enrolled (median age 59 [IQR 51, 67] years, 40% female, median duration of ERF 1.76 years [IQR 0.6, 3.98]. 88 participants attended both visits. Cognitive impairment was present in 44 participants (50%). Those with CI were more likely to have a history of hypertension (95.5 v 81.8%) and a higher recorded mean systolic blood pressure (148.3 vs 132.4mmHg) than those without (p<0.05). MFV declined during dialysis (mean; 49.8 to 43.21cm/s, p<0.001). Changes in MFV correlated with UF volume and presence of diabetes but not change in blood pressure. Participants scored lower on tests of processing speed and executive function during dialysis when compared to their non-dialysis day scores. Decline in test scores for language and executive function significantly correlated with the dialysis-related fall in MFV, p<0.05. CONCLUSIONS: Occult cognitive impairment is common and cognitive function was demonstrably worse during dialysis. Cerebral blood flow is reduced during HD and relates to UF volume and the decline in cognitive function seen. Ongoing study is examining whether the changes in MFV and cognitive function are related to long term decline in cognitive function.