19 Accuracy of Self- and Informant-Reported Domain-Specific Cognitive Ratings

Abstract

Objective:Diagnostic criteria for mild cognitive impairment (MCI) include a report of cognitive decline from the patient or a close informant. It is therefore important to understand the relationship between self- and informant-rated cognition and actual patient performance. Furthermore, it is unknown whether the nature of the relationship between the patient and their informant impacts accuracy of subjective reports. This study aimed to determine the association between informant report, self-report and objective cognitive performance based on relationship factors. We predicted that informant report would be more closely associated with objective performance than self-report after controlling for demographics and mood (Geriatric Depression Scale [mean= 1.4, SD=2]), especially among those who live with the participant and those who are spouses/partners.Participants and Methods:Participants (n = 338; age= 73.5 ±6.7) of varying diagnoses and their respective informants were drawn from the longitudinal cohort of the Michigan Alzheimer’s Disease Research Center (MADRC). The majority of informants were spouses/significant others (55.6%), followed by 23.7% being other family members and 20.7% were non- family members; 58.9% of informants live with the participant. Both respondents completed the Cognitive Change Index (CCI) to rate the patient’s cognitive status (higher scores indicating worsening cognition) across three domains: memory (12 questions), language (1 question), and attention/executive functioning (7 questions). These domains were matched to objective cognitive performance measured using the MADRC neuropsychological battery. Executive functioning and attention were assessed using Number Span Test Forward and Backward (NSF, NSB) and Trail Making Test Part B and Trail- Making Test Part A and B ratio (TMTB, TMTB: A); memory was measured using Craft Story 21 (Immediate and Delayed), Hopkins Verbal Learning Test-Revised (HVLT-R) Total Recall, Delayed Recall, and Benson Complex Figure (BCF) Delayed Recall; and Language was measured by the Controlled Oral Word Association Test (COWAT) and Animal fluency.Results:Linear regression adjusted for sex, race, and mood indicated that both patient and informant CCI ratings were significantly (p<.05) associated with objective cognitive performance. For every one unit increase on executive CCI items, there was a significant decline in executive functioning (NSF patient and informant ß= -0.09, NSB: [ßP= -.14; ßp-0.13]) and TMTB [ßP= 3.85; ß= 3.10 [% change]). Memory performance also declined per unit increase on CCI memory items: (Craft Story 21 Immediate [ßP=-0.32; ß= -0.37] and Delayed [ßP=-.40; ßp -.47], HVLT-R Total Recall [ßP= -.31; ßI=-.37] and Delayed Recall [ßP= -.16; ß=-.20], and BCF Delayed Recall [ßP= -.18; ß= -.23]. Similarly, one unit increase on the single CCI language item was associated with a decline in COWAT (ßP= -2.27; ß= -4.61) and Animal fluency (ßP= -1.88; ß= -3.03). Effect modification by participant-informant relationship type or participant-informant cohabitation was not significant.Conclusions:Patient and informant ratings are associated with objective measures of cognition regardless of the relationship between informant and patient or if they live together. This study was limited by a well-educated sample (mean= 16.1 years of education, SD= 2.4 years) with relatively limited diversity among participant-informant relationships. Future studies should replicate analyses across a larger and more diverse sample.