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Neurobiol Aging. 2016 Feb;38:82-92. doi: 10.1016/j.neurobiolaging.2015.10.017. Epub 2015 Oct 26.

Distinctive pathological mechanisms involved in primary progressive aphasias.

Author information

1
Faculty of Health Sciences, The University of Sydney, Lidcombe, New South Wales, Australia; Neuroscience Research Australia, Randwick, New South Wales, Australia; ARC Centre of Excellence in Cognition and its Disorders, Sydney, New South Wales, Australia. Electronic address: cristian.leyton@sydney.edu.au.
2
Department of Pathology, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
3
Neuroscience Research Australia, Randwick, New South Wales, Australia; ARC Centre of Excellence in Cognition and its Disorders, Sydney, New South Wales, Australia; School of Medical Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
4
Neuroscience Research Australia, Randwick, New South Wales, Australia; School of Medical Sciences, The University of New South Wales, Sydney, New South Wales, Australia.

Abstract

Primary progressive aphasia (PPA) comprises a heterogeneous group of neurodegenerative conditions that can be classified in three cliniconeuroanatomic syndromes. Limited information exists, however, about patterns of neuropathologic spreading and microscopic changes underpinning each syndrome. We performed an analysis of a longitudinal in vivo cohort and a postmortem PPA cohort to investigate neurodegeneration over time and to quantify microscopic changes in key language brain areas. The longitudinal analyses demonstrated distinctive patterns of topological extension of brain atrophy. Although semantic variant (sv-PPA) showed an eccentric pattern, nonfluent and/or agrammatic (nfv-PPA) and logopenic (lv-PPA) variants showed additional multifocal extension. The quantitative pathology showed that sv-PPA had neuronal loss and thinning in BA 38, whereas nfv-PPA showed thinning in BA 44/45 and evidence of microscopic involvement in BA 40/22. Although lv-PPA showed neuronal loss focused on BA 40/22, imaging results demonstrated widespread left-sided brain atrophy. These analyses provide an account of the pathologic process whereby each variant has stereotypical patterns of brain atrophy extension, which is largely determined by the specific pathologic type.

KEYWORDS:

Alzheimer's disease; Frontotemporal dementia; Logopenic variant; Nonfluent/agrammatic variant; Primary progressive aphasia; Quantitative pathology; Semantic variant

[Indexed for MEDLINE]

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