Participant–Informant Relationships Affect Quality of Life Ratings in Incipient and Clinical Alzheimer Disease

Abstract

Clinical trials in incipient and clinical Alzheimer disease (AD) often include informant-reported outcomes. Whereas informant reports in AD dementia may be modulated by the nature of participant-informant relationships, whether informant type affects reporting at earlier disease stages is less certain. We sought to determine the effects of participant-informant relationships on informant assessments of quality of life (QOL), functional abilities, and behavioral symptoms in individuals with normal cognition (NC), mild cognitive impairment (MCI), and mild-to-moderate AD dementia. Cross-sectional. Easton Center for Alzheimer Disease Research at the University of California, Los Angeles. A total of 399 individuals who met criteria for NC (N = 100), MCI [amnestic (N = 125) and nonamnestic (N = 61)], and AD (N = 113). Participants were subdivided into groups based on informant-participant relationships (spouse versus other). We examined informant effects on the Quality of Life-Alzheimer's Disease (QOL-AD) scale, the Functional Activities Questionnaire (FAQ), and the Neuropsychiatric Inventory (NPI). After adjustments for demographic and cognitive factors, spouse informants reported higher participant QOL in the amnestic MCI and AD groups than did other informants. No informant effects were seen on QOL-AD ratings in the nonamnestic MCI or NC groups or on the FAQ or NPI in the MCI and AD groups. Participant-informant relationships may modulate informant responses on subjective measures such as the QOL-AD in both incipient and clinical AD. Clinical trials that use informant measures may need to address these effects.