Background: Elderly patients admitted to hospital with heart failure (HF) often have cognitive impairment, but the association between these conditions is unclear. Methods and Results: We enrolled 43 patients admitted to a geriatric hospital with HF. We evaluated echocardiography, Mini Mental State Examination (MMSE), and extracellular water/total body water (ECW/TBW) ratio (Inbody S10). Mean age was 85.1±8.0 years (range, 60-99 years) and 44.2% of the patients were men. Mean MMSE score was 20.5±5.4, with 66.7% of the patients showing cognitive impairment (MMSE ≤23). There was a significant negative correlation of MMSE score with age (r=−0.344, P=0.032), regular alcohol drinking (r=0.437, P=0.007), uric acid level (r=0.413, P=0.010), and ECW/TBW ratio (r=−0.437, P=0.007). On stepwise regression analysis including these covariates, MMSE score was significantly associated with the ECW/TBW ratio (β=0.443, P=0.009). When several echocardiography parameters (i.e., end-diastolic left ventricular volume, r=0.327, P=0.048; left atrial volume index, r=−0.411, P=0.012; and transmitral inflow A wave velocity, r=−0.625, P=0.001) were added to the model, MMSE score was found to be related to the A wave (P=0.001) and to atrial volume index (P=0.015), which are measures of diastolic function. Conclusions: In elderly patients with HF, cognitive function might be influenced by body water distribution and diastolic heart function.

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