MO392: Mildly Impaired Kidney Function May Be Associated With the Risk of Hippocampal Atrophy in Young and Midlife Adults

Abstract BACKGROUND AND AIMS To date, associations between kidney function and brain structural abnormalities have been described in several studies [1]. Reports of renal function in relation to hippocampal atrophy have been scarce and the majority of studies have been focussed on older end-stage renal disease populations [2]. Particularly, with the ageing process, the hippocampus has a greater propensity to atrophy than other cerebral structures.The purpose of this study was to evaluate the relationship between kidney function assessed by estimated glomerular filtration rate (eGFR) and the degrees of hippocampal atrophy among young and midlife adults. METHOD In this cross-sectional study, the risk factors for hippocampal atrophy were evaluated in a cohort of 219 non-diabetic chronic kidney disease (CKD) patients, age ≤ 55 years, who had undergone magnetic resonance imaging (MRI) of the brain. The eGFR was calculated using the CKD-EPI formula. Hippocampal volume (HV) was assessed in brain MRIs with the Scheltens’ Medial Temporal Atrophy score, including a 5-stage escalation—0: no atrophy, 1: only widening of choroid fissure, 2: also widening of the temporal horn of lateral ventricle, 3: moderate loss of HV (decrease in height) and 4: severe loss of HV [3]. RESULTS In our group, the median and interquartile ranges (IQR) of age was 45 (14) years, 57.53% (126 patients) being males. The median eGFR was 100.6 (34.7) mL/min/1.73m2 and 46.75% (102 patients) presented with mild reduction in eGFR (eGFR between 60 to 89 mL/min/1.73m2). In univariable regression analysis, eGFR (R2 = 0.207, P < 0.001), arterial hypertension (R2 = 0.018, P = 0.045), dyslipidaemia (R2 = 0.044, P = 0.002), haematocrit (R2 = 0.021, P = 0.032), natrium levels (R2 = 0.018, P = 0.047), and potassium levels ( R2 = 0.019, P = 0.042) were associated with smaller HV. In multivariable regression analysis, eGFR [odds ratio (OR), 0.95; 95% confidence interval (CI), 0.94–0.97; P < 0.001) and serum natrium (OR, 0.91; 95% CI, 0.83–0.98; P = 0.027) were significantly associated with hippocampal atrophy. CONCLUSION This cross-sectional study shows that mild decrease in eGFR is independently associated with hippocampal atrophy. Our results suggest that brain imaging tests should be routinely performed in patients with mild reduction of eGFR, as the hippocampal atrophy process appears to be due, in part, to the mild renal dysfunction itself.