Fig 1.
(A) Study protocol. Cognitive function and cerebral blood dynamics were assessed twice for each participant (first and second assessments). Assessment intervals varied due to clinical constraints. As part of routine clinical care, participants were advised to consume 1,500 mL of fluid per day. (B) Expected relationship between fluid intake and cognitive change. A positive association was anticipated between fluid intake and cognitive improvement, provided that excessive intake does not result in adverse effects (yellow-shaded range). This expectation was based on the known relationship between blood volume and cardiac output in patients with heart failure. (C) Study hypothesis. Adequate fluid intake was hypothesised to alleviate dehydration, enhance cerebral blood dynamics, and promote cognitive improvement within the yellow-shaded range. Blue boxes illustrate the components of the hypothesis.
Table 1.
Participant characteristics and assessment dates relative to admission.
Fig 2.
Correlations between the amount of fluid intake and changes in cognitive parameters.
The value shown in the corner of each plot represents the Spearman’s correlation coefficient (rho), averaged across bootstrap iterations; an asterisk (*) denotes a significant correlation. The filled dots indicate individual data points included in the statistical analysis, whereas circled dots denote outliers that were excluded. A least square regression line was included for significant correlations. Abbreviations: mnFI, amount of fluid intake normalised using lean body mass and averaged across the study period; MMSE-J, Japanese version of the Mini-Mental State Examination; FAB, Frontal Assessment Battery.
Table 2.
Correlations between fluid intake and ultrasonographic parameters.
Fig 3.
Correlations between the amount of fluid intake and changes in ultrasonographic parameters.
The correlations are shown for the (A) left and (B) right common carotid arteries. The number displayed in the corner of each plot indicates Spearman’s rank correlation coefficient (rho), averaged across bootstrap iterations; an asterisk (*) indicates significant correlation. Filled dots indicate the individual data points included in the statistical analysis, whereas circled dots indicate outliers excluded from the analysis. Least squares regression lines were added for significant correlations. Abbreviations: DA, diameter of the artery; PSV, peak systolic velocity; EDV, end-diastolic velocity; RI, resistance index; mnFI, amount of fluid intake normalised by lean body mass and averaged across the study period; CCA, common carotid artery.
Table 3.
Correlations between cognitive state and ultrasonographic parameters.
Fig 4.
Correlations between cognitive state and ultrasonographic parameters at the second assessment.
The number displayed at the corner of each plot indicates Spearman’s correlation coefficient (rho) averaged across bootstrap iterations. Filled dots indicate the individual data considered for statistical analysis, whereas circled dots indicate the outliers excluded from the analysis. Least square regression lines were added for significant correlations. Abbreviations: MMSE-J, Japanese version of the Mini-Mental State Examination; FAB, Frontal Assessment Battery; DA, diameter of the artery; PSV, peak systolic velocity; EDV, end-diastolic velocity; RI, resistance index; CCA, common carotid artery.