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Background: Discrepancy between caregiver and patient assessments of apathy in mild cognitive impairment (MCI) is considered an index of apathy unawareness, independently predicting progression to AD dementia. However, its neural underpinning are uninvestigated. Objective: To explore the [18F]FDG PET-based metabolic correlates of apathy unawareness measured through the discrepancy between caregiver and patient self-report, in patients diagnosed with MCI. Methods: We retrospectively studied 28 patients with an intermediate or high likelihood of MCI-AD, progressed to dementia over an average of two years, whose degree of apathy was evaluated by means of the Apathy Evaluation Scale (AES) for both patients (PT-AES) and caregivers (CG-AES). Voxel-based analysis at baseline was used to obtain distinct volumes of interest (VOIs) correlated with PT-AES, CG-AES, or their absolute difference (DISCR-AES). The resulting DISCR-AES VOI count densities were used as covariates in an inter-regional correlation analysis (IRCA) in MCI-AD patients and a group of matched healthy controls (HC). Results: DISCR-AES negatively correlated with metabolism in bilateral parahippocampal gyrus, posterior cingulate cortex, and thalamus, PT-AES score with frontal and anterior cingulate areas, while there was no significant correlation between CG-AES and brain metabolism. IRCA revealed that MCI-AD patients exhibited reduced metabolic/functional correlations of the DISCR-AES VOI with the right cingulate gyrus and its anterior projections compared to HC. Conclusions: Apathy unawareness entails early disruption of the limbic circuitry rather than the classical frontal-subcortical pathways typically associated with apathy. This reaffirms apathy unawareness as an early and independent measure in MCI-AD, marked by distinct pathophysiological alterations. [ABSTRACT FROM AUTHOR]

Background: Apathy is a frequent behavioral symptom of Alzheimer's disease (AD). The Apathy Evaluation Scale (AES) is a tool exploring the perception of apathy by both caregivers (CG-AES) and patients (PT-AES), and the discrepancy in their ratings is a proxy of patients' disease unawareness. Objective: To assess in a cohort study of patients with amnesic mild cognitive impairment (aMCI) whether apathy and awareness of apathy predict progression to dementia and timing. Methods: From the global AES scores of 110 patients with aMCI and their caregivers, we obtained two principal indices for analysis: 1) 'Apathy', the mean of PT-AES and CG-AES, and 2) 'Discrepancy', obtained by subtracting CG-AES from PT-AES. Patients were followed with visits every six months for three years or until dementia. AES indices and the principal demographical/neuropsychological variables were filtered from multicollinearity. The most robust variables entered a logistic regression model and survival analyses (Cox regression, log-rank test of Kaplan-Meier curves) to estimate which predicted the risk and timing of progression, respectively. Results: Sixty patients (54.5%) developed dementia (57 AD) after 6.0–36.0 months, 22 (20%) remained in an MCI stage, and 28 (25.5%) dropped out. 'Discrepancy' was a robust and accurate predictor of the risk of progression (AUC = 0.73) and, after binarization according to a computed cutoff, of timing to dementia. Conclusion: A structured evaluation of apathy, both self-assessed and estimated by caregivers, can provide useful information on the risk and timing of progression from aMCI to dementia. The discrepancy between the two estimates is a fairly reliable index for prediction purposes as a proxy of disease unawareness. [ABSTRACT FROM AUTHOR]

Background: In Alzheimer's disease, apathy is a common behavioral sign (AD). The Apathy Evaluation Scale (AES) is a measure that investigates caregivers' (CG‐AES) and patients' (PT‐AES) perceptions of apathy, and the discrepancy in their evaluations is a proxy for patients' illness unawareness. We aimed to determine whether apathy and awareness of apathy predict dementia development and timing in a cohort study of individuals with amnesic mild cognitive impairment (aMCI). Method: We acquired two main indices for analysis from the global AES scores of 110 patients with aMCI and their caregivers: i) 'Apathy,' the mean of PT‐AES and CG‐AES, and ii) 'Discrepancy,' obtained by subtracting CG‐AES from PT‐AES. Patients were seen every six months for three years, or until they developed dementia. The AES indices and the major demographical/neuropsychological variables were filtered for multicollinearity, and the most robust variables were entered into a logistic regression model and survival analyses (Cox regression, log‐rank test of Kaplan‐Meier curves) to estimate which variables predicted the risk and timing of progression, respectively. Result: 60 patients (54.5%) showed signs of dementia (57 AD) after 6.0‐36.0 months, whereas 28 patients (25.5%) dropped out and 22 patients (20%) were still in an MCI stage. The "Discrepancy" index was a reliable and accurate predictor of the probability of progression (AUC = 0.73) and, after binarization in accordance with a calculated cutoff, of the time to dementia. Conclusion: A structured assessment of apathy, both by the patient and by the caregiver, can reveal important details about the likelihood and timing of the transition from aMCI to dementia. The difference between the two estimations serves as a reliable predictor of illness unawareness by patients. [ABSTRACT FROM AUTHOR]

Background: Discrepancy between caregiver and patient assessments of apathy in mild cognitive impairment (MCI) is considered an index of apathy unawareness, independently predicting progression to AD dementia. However, its neural underpinning are uninvestigated., Objective: To explore the [18F]FDG PET-based metabolic correlates of apathy unawareness measured through the discrepancy between caregiver and patient self-report, in patients diagnosed with MCI., Methods: We retrospectively studied 28 patients with an intermediate or high likelihood of MCI-AD, progressed to dementia over an average of two years, whose degree of apathy was evaluated by means of the Apathy Evaluation Scale (AES) for both patients (PT-AES) and caregivers (CG-AES). Voxel-based analysis at baseline was used to obtain distinct volumes of interest (VOIs) correlated with PT-AES, CG-AES, or their absolute difference (DISCR-AES). The resulting DISCR-AES VOI count densities were used as covariates in an inter-regional correlation analysis (IRCA) in MCI-AD patients and a group of matched healthy controls (HC)., Results: DISCR-AES negatively correlated with metabolism in bilateral parahippocampal gyrus, posterior cingulate cortex, and thalamus, PT-AES score with frontal and anterior cingulate areas, while there was no significant correlation between CG-AES and brain metabolism. IRCA revealed that MCI-AD patients exhibited reduced metabolic/functional correlations of the DISCR-AES VOI with the right cingulate gyrus and its anterior projections compared to HC., Conclusions: Apathy unawareness entails early disruption of the limbic circuitry rather than the classical frontal-subcortical pathways typically associated with apathy. This reaffirms apathy unawareness as an early and independent measure in MCI-AD, marked by distinct pathophysiological alterations.