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Very Early Changes in Olfactory Functioning Due to Alzheimer's Disease and the Role of Apolipoprotein E in Olfactiona

Authors

  • ANNA W. BACON,

    1. SDSU-UCSD Joint Doctoral Program in Clinical Psychology, San Diego, California 92103, USA
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  • MARK W. BONDI,

    1. California State University, San Marcos, California, USA
    2. Department of Neuroscience, University of California, San Diego, La Jolla, California 92093-0957, USA
    3. Veterans Affairs Medical Center, San Diego, California, USA
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  • DAVID P. SALMON,

    1. Department of Neuroscience, University of California, San Diego, La Jolla, California 92093-0957, USA
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  • CLAIRE MURPHY

    Corresponding author
    1. Department of Neuroscience, University of California, San Diego, La Jolla, California 92093-0957, USA
    2. San Diego State University, San Diego, California 92120, USA
    3. University of California, San Diego, School of Medicine, La Jolla, California 92093-0957, USA
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  • a

    Supported by NIA Grants AG09203 and AG12674 and by the Medical Research Service of the Department of Veterans Affairs.

Address for correspondence: Dr. Claire Murphy, Life Span Human Senses, 6363 Alvarado Court, Suite 101, San Diego, CA 92120. Tel: (619) 594-4559; fax: (619) 594-3773; email: cmurphy @sunstroke.sdsu.edu

Abstract

ABSTRACT: Alzheimer's disease (AD) is a progressive neurodegenerative illness marked by memory loss and at least one other cognitive disturbance. Early diagnosis of the disease has proved difficult and has therefore been the focus of much research. Apolipoprotein E (ApoE), a protein manufactured and distributed throughout the body, has shown specificity of binding to the βA4 peptide, the primary component in the senile plaques of AD. Furthermore, the ApoE, epsilon 4 (ɛ4) allele, is overrepresented in AD. These two lines of evidence suggest that ApoE, specifically the ɛ4 allele, plays an important role in the development of AD. Further support for this hypothesis appears in neuropsychological data showing cognitive decrements in ostensibly nondemented individuals with the ɛ4 allele, compared to those without the allele. It is also well known that olfaction is compromised in AD. Thus, the purpose of this study was twofold: (1) to examine very early changes in olfactory functioning due to AD and (2) to examine the role of ApoE in olfactory functioning in people at risk for AD by virtue of early cognitive decline. Results demonstrated changes in olfactory threshold the year immediately preceding change in diagnosis from normal control to AD. Also, in individuals with mild cognitive impairment, those with the ApoE ɛ4 allele show poorer thresholds than those without the ɛ4 allele.

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