Free‐listing and semantic knowledge: A diagnostic tool for detecting Alzheimer’s disease?

Abstract

AbstractBackgroundA semantic memory impairment figures prominently among the manifestations of Alzheimer’s disease (AD). That impairment manifests itself relatively early in the disease trajectory with longitudinal studies showing evidence in patients with mild cognitive impairment and preclinical AD. We investigate the impact of AD on specific semantic categories integral to daily function: living kinds and artefacts.MethodWe relied on a “free‐listing task” as developed in cultural domain analysis, and assessed its relationship with other cognitive and functional tests in clinical use. We chose the written version for the elicitation of the free‐lists that we analyze here. A written format leads to the generation of longer lists than an oral elicitation. The participant pool was comprised of 19 AD patients and a control group, 15 cognitively normal age‐matched adults.ResultThe median number of items generated in each list for the patients was 12 for living things and 18 for man‐made objects, for the control group, 39 and 45, respectively. Controlling for age, education, estimate of premorbid intellectual ability, and sex, group membership (AD or control) predicts performance in the free‐listing in the two categories. Holding demographic variables constant, functional status is inversely related to the performance on free‐listing.ConclusionEven when provided the modality (written) to generate longer lists, individuals with AD still performed worse than controls. Our findings confirm previous observations identifying an impairment of semantic knowledge in AD. Free‐listing is effective at detecting this impairment. This easy‐to‐administer, cost‐effective tool could facilitate the fast preliminary characterization of AD in distinct cultural environments.