Prevalence and pathological correlates of unawareness of memory impairment in non‐demented individuals with autosomal dominant Alzheimer’s disease: an item‐level investigation of the Memory Complaints Scale

Abstract

AbstractBackgroundAwareness of memory was previously found to be reduced in the pre‐dementia stages, reaching unawareness/anosognosia 6‐years before dementia onset in individuals who carry the PSEN1 E280A mutation for autosomal dominant Alzheimer’s disease (Vannini et al.,2021). Whether there are potential differences in awareness for specific types of situations involving memory as well as their association with molecular markers of AD disease progression in preclinical AD is unknown. Here, we investigated memory awareness on an item‐level basis as well as its relationship to neocortical amyloid and regional tau levels in non‐demented mutation carriers and non‐carrier family members.MethodA total of 119 Colombian kindred members, 56 carriers (7 mildly impaired) and 63 non‐carriers were included (Table.1). Awareness indexes were calculated using participant and study‐partner discrepancy scores for each of the 15 questions of the Memory Complaint Scale (Spanish version). A score of ≥0 indicates that the participant is aware and <0 unaware. A subset of 67 kindred members (N = 31 carriers, 1 impaired) underwent amyloid (PiB) and tau (FTP) scans. For each question, odds ratio and Fisher’s exact test were used to evaluate prevalence of awareness/unawareness in carriers and non‐carriers. Pearson correlations, corrected for multiple comparisons, were used to assess the associations between awareness and pathology in the mutation carriers.ResultMutation carriers had significantly decreased overall awareness (p = 0.03), increased mean cortical amyloid (p<0.001) and inferior temporal tau (p = 0.001), compared to non‐carriers. Two questions (items 10 and 15), showed significantly lower awareness in the carriers than non‐carriers (both p = 0.002, Table.2). These results remained significant after removing impaired carriers. In carriers, decreased awareness was related to increased tau for 5/15 (33%) questions (Table.3 and Figure.1). No significant associations were found between awareness and amyloid.ConclusionOur results support previous findings that awareness is decreased in pre‐dementia stages of AD and related to tau, and not to amyloid pathology (Gagliardi et al.,2021). Importantly, we found that loss of awareness of specific memory items could differentiate carriers from non‐carriers. These findings support the usefulness of study‐partner‐reported cognitive decline. Individuals who become unaware of cognitive changes may represent a specific risk group to harbor pathology and develop AD dementia.