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Fluorodeoxyglucose positron emission tomography in semantic dementia after 6 months of memantine: an open-label pilot study

Authors

  • Tiffany W. Chow,

    Corresponding author
    1. Division of Neurology, Baycrest, Toronto, Canada
    2. Department of Psychiatry, Baycrest, Toronto, Canada
    3. Dept of Psychiatry, University of Toronto, Toronto, Canada
    4. Dept of Medicine, Division of Neurology, University of Toronto, Toronto, Canada
    • Rotman Research Institute, Baycrest, Toronto, Canada
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  • David Fam,

    1. Rotman Research Institute, Baycrest, Toronto, Canada
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  • Ariel Graff-Guerrero,

    1. Centre for Addiction and Mental Health PET Centre, Toronto, Canada
    2. Dept of Psychiatry, University of Toronto, Toronto, Canada
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  • Nicolaas P. G. Verhoeff,

    1. Department of Psychiatry, Baycrest, Toronto, Canada
    2. Kunin-Lunenfeld Applied Research Unit, Baycrest, Toronto, Canada
    3. Dept of Psychiatry, University of Toronto, Toronto, Canada
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  • David F. Tang-Wai,

    1. Dept of Medicine, Division of Neurology, University of Toronto, Toronto, Canada
    2. University Health Network Memory Clinic, Toronto, Canada
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  • Mario Masellis,

    1. Dept of Medicine, Division of Neurology, University of Toronto, Toronto, Canada
    2. Sunnybrook Health Sciences Centre L.C. Campbell Cognitive Neurology Research Unit, Department of Medicine (Neurology), Sunnybrook Research Institute, Canada
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  • Sandra E. Black,

    1. Rotman Research Institute, Baycrest, Toronto, Canada
    2. Dept of Medicine, Division of Neurology, University of Toronto, Toronto, Canada
    3. Sunnybrook Health Sciences Centre L.C. Campbell Cognitive Neurology Research Unit, Department of Medicine (Neurology), Sunnybrook Research Institute, Canada
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  • Alan A. Wilson,

    1. Centre for Addiction and Mental Health PET Centre, Toronto, Canada
    2. Dept of Psychiatry, University of Toronto, Toronto, Canada
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  • Sylvain Houle,

    1. Centre for Addiction and Mental Health PET Centre, Toronto, Canada
    2. Dept of Psychiatry, University of Toronto, Toronto, Canada
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  • Bruce G. Pollock

    1. Centre for Addiction and Mental Health PET Centre, Toronto, Canada
    2. Dept of Psychiatry, University of Toronto, Toronto, Canada
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Correspondence to: Tiffany Chow, MD, E-mail: tchow@rotman-baycrest.on.ca

Abstract

Objectives

To follow up on the increases we reported in normalized metabolic activity in salience network hubs from a 2-month open-label study of memantine in frontotemporal dementia (FTD).

Methods

We repeated fluorodeoxyglucose positron emission tomography (FDG-PET) after 6 months of drug use and subjected the data to Statistical Parametrical Mapping (SPM) analysis to reveal clusters of significant change from baseline. We also sought correlations between changes in behavioral disturbances on the Frontal Behavioral Inventory (FBI) and the PET signal.

Results

Recruitment of one progressive nonfluent aphasia and one behavioral variant FTD precluded statistical analysis for any FTD subtype other than semantic dementia (SD). The baseline-to-6-month interval showed increased normalized metabolic activity in the left orbitofrontal cortex (p < 0.002) for five participants with SD. The 2–6-month interval revealed a late increase in normalized metabolic activity in the left insula (p < 0.013), right insula (p < 0.009), and left anterior cingulate (p < 0.005). The right anterior cingulate showed both an initial increase and a delayed further increase (2–6 months, p < 0.016). FBI scores worsened by 43.3%. One participant with SD opted not to continue memantine beyond 2 months yet showed similar FDG-PET increases.

Conclusions

Increases in normalized cortical metabolic activity in salience network hubs were sustained in SD over a 6-month period. Because one participant without medication also showed these changes, further investigation is recommended through a double-blind, placebo-controlled study with FDG-PET as an outcome measure. Copyright © 2012 John Wiley & Sons, Ltd.

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