Performance of cognitively complex “instrumental activities of daily living” (IADL) has previously been related to amyloid deposition in preclinical Alzheimer’s disease.

We aimed to investigate the relationship between IADL performance and cerebral tau accumulation in cognitively normal older adults.

Cross-sectional.

Data was collected in the Anti-Amyloid Treatment in Asymptomatic Alzheimer’s (A4) and Longitudinal Evaluation of Amyloid Risk and Neurodegeneration (LEARN) studies.

Participants (n = 447, age 71.9+4.9 years, 57.5% female) who underwent tau positron emission tomography were selected from the A4 and LEARN studies.

IADL performance was measured using the self- and study partner-reported versions of the Alzheimer’s Disease Cooperative Study Activities of Daily Living — Prevention Instrument (ADCS ADL-PI). We also investigated discordance between participants and their study partners. Cross-sectional associations between entorhinal and inferior temporal tau (independent variables) and ADCS ADL-PI total scores, item-level scores and discordance (dependent variables) were investigated in linear and logistic regressions. Analyses were adjusted for age, sex and education and a tau by amyloid interaction was also included.

Participants and their study partners reported high levels of IADL performance. Entorhinal and inferior temporal tau were related to study partner but not to self-reported total ADCS ADL-PI scores. The association was not retained after adjustment for global cerebral amyloid burden. At the item level, greater entorhinal tau was associated with study partner-reported difficulties remembering important dates (odds ratio (OR) = 1.24, 95% confidence interval (95%CI) = [1.06, 1.45], p = 0.008) and difficulties remembering the details of TV programs and movies (OR = 1.32, 95%CI = [1.08, 1.61], p = 0.007). Greater inferior temporal tau was associated with self-reported difficulties managing to find personal belongings (OR = 1.23, 95%CI = [1.04, 1.46], p = 0.018) and study partner-reported difficulties remembering the details of TV programs and movies (OR = 1.39, 95%CI = [1.11, 1.75], p = 0.005). Discordance between participant and study partner-report was more likely with greater entorhinal (OR = 1.18, 95%CI = [1.05, 1.33], p = 0.005) and inferior temporal tau burden (OR = 1.29, 95%CI = [1.10, 1.51], p = 0.002).

We found a cross-sectional relationship between study partner-reported everyday functioning and tau in cognitively normal older adults. Participants were more likely to self-report difficulties differently from their study partners when tau burden was higher. This may hint at an altered early-disease awareness of functional changes and underscores the importance of self-report of IADL functioning in addition to collateral report by a study partner.