Research article summary (published 29 Sep 2007):

Category specific deficits in Alzheimer's disease: fact or artefact?

Full Abstract

Impairments in semantic memory commonly occur in Alzheimer's Disease (AD) but do these occur along category-specific lines? We administered a confrontation naming task comprising living and nonliving items to 68 individuals with AD and 59 age-matched control participants, in a study designed to address some of the methodological issues affecting investigation of category effects. In Experiment 1, stimuli were matched for familiarity and word frequency and also visual complexity, and the AD group showed a differential deficit in nonliving things. In Experiment 2, however, living and nonliving stimuli were matched for age-of-acquisition, name agreement, word frequency, and naming accuracy of elderly controls and there was no categorical impairment in the AD group. The AD group was subdivided first into mild and moderate AD, and then into normal or impaired overall naming groups and performance was reanalysed, but there was still no significant category deficit in any group. Converging evidence was provided by hierarchical regressions across items, as age-of-acquisition, name agreement and word frequency were significant predictors of naming performance in mild and moderate AD groups, but category was not. In Experiment 3, stimulus items were matched for familiarity and naming accuracy of elderly controls when their performance was off-ceiling, and again no differential effect of category was found. When we reduced slightly how closely matched stimuli were for familiarity we then found a differential impairment in living things in the AD group. When reviewing the changing pattern of results from use of different stimulus sets, we concluded that the main determinant of whether or not a categorical impairment of either sort is found in AD is which stimulus properties are controlled during stimulus selection. We conclude that AD does not generally lead to a selective category loss in semantic knowledge.

Author information

Author/s: Tippett, Lynette J (LJ); Meier, Sandra L (SL); Blackwood, Kirsty (K); Diaz-Asper, Catherine (C);

Affiliation: Department of Psychology, University of Auckland, Auckland, New Zealand. l.tippett(-atsign-)auckland.ac.nz

Grants: R01-AG14082 (Agency:NIA NIH HHS)

Journal and publication information

Publication Type: Journal Article; Multicenter Study; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Cortex; a journal devoted to the study of the nervous system and behavior (Cortex), published in Italy. (Language: eng)

Reference: 2007-Oct; vol 43 (issue 7) : pp 907-20

Dates: Created 2007/10/18; Completed 2007/11/28;

PMID: 17941349, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Aged Aged, 80 and over Alzheimer Disease - complications Analysis of Variance Case-Control Studies Concept Formation Female Humans

Male Matched-Pair Analysis Memory Disorders - classification; complications Middle Aged Reference Values Semantics Severity of Illness Index Verbal Behavior - physiology

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