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Neurobiol Aging. 2015 Mar;36(3):1245-52. doi: 10.1016/j.neurobiolaging.2014.12.013. Epub 2014 Dec 16.

Working memory and language network dysfunctions in logopenic aphasia: a task-free fMRI comparison with Alzheimer's dementia.

Author information

1
Department of Radiology, Mayo Clinic, Rochester, MN, USA. Electronic address: whitwell.jennifer@mayo.edu.
2
Department of Neurology (Behavioral Neurology), Mayo Clinic, Rochester, MN, USA.
3
Department of Neurology (Speech Pathology), Mayo Clinic, Rochester, MN, USA.
4
Department of Psychiatry and Psychology (Neuropsychology), Mayo Clinic, Rochester, MN, USA.
5
Department of Health Sciences Research (Biostatistics), Mayo Clinic, Rochester, MN, USA.
6
Department of Radiology, Mayo Clinic, Rochester, MN, USA.
7
Department of Radiology, Mayo Clinic, Rochester, MN, USA; Department of Information Technology, Mayo Clinic, Rochester, MN, USA.

Abstract

We aimed to determine whether network-level functional connectivity differs in 2 clinical variants of Alzheimer's disease: logopenic primary progressive aphasia (lvPPA) and dementia of the Alzheimer's type (DAT). Twenty-four lvPPA subjects with amyloid deposition on positron emission tomography and task-free functional magnetic resonance imaging were matched to 24 amyloid-positive DAT subjects and 24 amyloid-negative controls. Independent-component analysis and spatial-temporal dual regression were used to assess functional connectivity within the language network, left and right working memory networks, and ventral default mode network. lvPPA showed reduced connectivity in left temporal language network and inferior parietal and prefrontal regions of the left working memory network compared with controls and DAT. Both groups showed reduced connectivity in the parietal regions of the right working memory network compared with controls. Only DAT showed reduced ventral default mode network connectivity compared with controls. Aphasia severity correlated with connectivity in the left working memory network within lvPPA. Patterns of network dysfunction differ across these 2 clinical variants of Alzheimer's disease, with lvPPA particularly associated with disruptions in the language and left working memory networks.

KEYWORDS:

Alzheimer's disease; Functional imaging; Language; MRI; Primary progressive aphasia

[Indexed for MEDLINE]
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