Does Informant-Based Reporting of Cognitive Decline Correlate with Age-Adjusted Hippocampal Volume in Mild Cognitive Impairment and Alzheimer's Disease?

Background: Informant-based measures are effective screening tools for cognitive impairment. The Alzheimer's Questionnaire (AQ) is a subjective, informant-based measure that detects amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD) with high sensitivity and specificity and has been shown to predict amyloid burden.

Objective: To determine whether informant-based report of cognitive decline correlates with hippocampal volume changes in MCI and AD.

Methods: Retrospective chart review of 139 clinically referred patients with clinical diagnoses of aMCI or mild dementia due to AD was conducted. Diagnostic status (clinical diagnosis made by a neurologist), NeuroQuant measured MRI brain with percentile rank hippocampal volume, Montreal Cognitive Assessment (MoCA) total, AQ-Total score, and demographic variables were extracted from medical records. Spearman correlation was used to assess the relationship between hippocampal volume and AQ-Total. The AQ was used to assign diagnostic status. Thus, the relationship between the AQ and diagnostic status was excluded.

Results: The sample include 88 female and 51 male participants. The mean age was 74.37±9.45, mean MOCA was 22.65±4.18, mean education was 14.80±3.35, and mean AQ score was 10.54±5.22. Hippocampal volume and the AQ correlation was  = -0.33 [95%CI -0.47 to -0.17],  < 0.0001.

Conclusion: In a mixed-clinical sample of patients presenting to an outpatient memory disorders center, higher endorseme-nts of functional impairments by caregivers were significantly associated with smaller hippocampal volumes. When used in conjunction with other available measures, these findings further support the role of the AQ in clinical decision-making and demonstrate an additional relationship between clinical measures and volumetric MRI.