Neuroimaging of Primary Progressive Aphasia

Review Article

Neuroimaging of Primary Progressive Aphasia

Jonathan D Rohrer and Nick C Fox

Affiliation: Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, UK

Submission date: 17th July 2009, Revision date: 20th August 2009, Acceptance date: 1st September 2009

ABSTRACT

In this review, we discuss the neuroimaging features of primary progressive aphasia (PPA), a group of neurodegenerative disorders characterized by an initial speech and language deficit. The PPA syndromes, semantic dementia (SD), progressive non-fluent aphasia (PNFA), and logopenic/phonological aphasia (LPA), are defined clinically, but there are emerging patterns of clinico-imaging–pathological correlation. Each of the PPA subtypes has a distinctive initial pattern of atrophy or hypometabolism affecting the left hemisphere language network that is consistent with the speech  and language and other cognitive/behavioral deficits present: SD is associated with disease affecting the anteroinferior temporal lobes, PNFA with the left insula and inferior frontal lobes, LPA with the left posterior superior temporal and inferior parietal lobes, and familial PPA caused by mutations in the progranulin gene with the left frontal, temporal, and parietal lobes. As we stand on the verge of clinical trials in PPA, the combination of structural, functional, and molecular imaging holds the promise of defining in vivo cohorts that are likely to have a common pathological target for disease-modifying treatments.

Keywords: primary progressive aphasia, frontotemporal dementia, frontotemporal lobar degeneration, logopenic aphasia, semantic dementia, progressive non-fluent aphasia
Correspondence: Nick Fox, Dementia Research Centre, Institute of Neurology, Queen Square, London WC1N 3BG, UK; Tel: +44-207-829-8773; fax: +44-207-676-2066; e-mail: nfox@dementia.ion.ucl.ac.uk