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The Relationship Between Semantic Knowledge and Conceptual Apraxia in Alzheimer Disease

Falchook, Adam D. MD*,†; Mosquera, Diana M. BHS*,‡; Finney, Glen R. MD*; Williamson, John B. PhD*,†; Heilman, Kenneth M. MD*,†

Cognitive and Behavioral Neurology: December 2012 - Volume 25 - Issue 4 - p 167–174
doi: 10.1097/WNN.0b013e318274ff6a
Original Studies

Background: Conceptual apraxia (CA), a feature of Alzheimer disease (AD), can be detected by asking participants to identify the correct tool to act on an object. Assessment can be based on either learned associations (a tool selection test) or the mechanical properties that the tool needs to alter the target object (an alternative tool selection test).

Objectives: We wanted to determine whether knowledge of semantic taxonomic relations (intrinsic properties shared by items) correlated with performance on tests for CA in people with AD or amnestic mild cognitive impairment (aMCI).

Methods: We tested 10 participants with AD, 12 with aMCI, and 18 healthy older adults for CA using an alternative tool selection test, a tool selection test, and a test of taxonomic relations.

Results: The aMCI group did not differ from the control group on the CA tests. The patients with AD were impaired on all tests except tool selection; their performance on the alternative tool selection test correlated significantly with their performance on the taxonomic relations test.

Conclusions: The correlation between performances on the alternative tool selection test and the taxonomic relations test in AD suggests a common pathophysiologic substrate, either impairment in accessing conceptual-semantic representations or a degradation of these representations.

*Cognitive and Memory Disorder Clinics, Department of Neurology and Center for Neuropsychological Studies, University of Florida

College of Public Health and Health Professions, University of Florida, Gainesville, FL

Malcom Randall Veterans Affairs Medical Center, Gainesville, FL

Partially supported by the Florida Department of Elder Affairs and the Department of Veterans Affairs Office of Research and Development. D.M.M. received research funding from the University of Florida University Scholars Program.

The authors declare no conflicts of interest.

Reprints: Adam D. Falchook, MD, Department of Neurology, University of Florida, College of Medicine, McKnight Brain Institute (L3-100), 100 South Newell Drive, P.O. Box 100236, Gainesville, FL 32610-0236 (e-mail:

Received November 11, 2011

Accepted May 3, 2012

© 2012 Lippincott Williams & Wilkins, Inc.