Brain Advance Access published online on October 1, 2009
Brain, doi:10.1093/brain/awp235
Non-verbal sound processing in the primary progressive aphasias
1 Dementia Research Centre, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK 2 Department of Neuro-otology, National Hospital for Neurology and Neurosurgery, London, UK 3 Ear Institute, School of Life and Medical Sciences, University College London, UK 4 Medical Statistics Unit, London School of Hygiene and Tropical Medicine, University College London, UK
Correspondence to:
Dr J. D. Warren, Dementia Research Centre, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK. E-mail: jwarren{at}drc.ion.ucl.ac.uk
Little is known about the processing of non-verbal sounds in the primary progressive aphasias. Here, we investigated the processing of complex non-verbal sounds in detail, in a consecutive series of 20 patients with primary progressive aphasia [12 with progressive non-fluent aphasia; eight with semantic dementia]. We designed a novel experimental neuropsychological battery to probe complex sound processing at early perceptual, apperceptive and semantic levels, using within-modality response procedures that minimized other cognitive demands and matching tests in the visual modality. Patients with primary progressive aphasia had deficits of non-verbal sound analysis compared with healthy age-matched individuals. Deficits of auditory early perceptual analysis were more common in progressive non-fluent aphasia, deficits of apperceptive processing occurred in both progressive non-fluent aphasia and semantic dementia, and deficits of semantic processing also occurred in both syndromes, but were relatively modality specific in progressive non-fluent aphasia and part of a more severe generic semantic deficit in semantic dementia. Patients with progressive non-fluent aphasia were more likely to show severe auditory than visual deficits as compared to patients with semantic dementia. These findings argue for the existence of core disorders of complex non-verbal sound perception and recognition in primary progressive aphasia and specific disorders at perceptual and semantic levels of cortical auditory processing in progressive non-fluent aphasia and semantic dementia, respectively.
Key Words: auditory perception; non-verbal sound; agnosia; dementia; environmental sounds
Abbreviations: CI, confidence interval; FA, frequency average; HFA, high frequency average; MMSE, Mini-Mental State Examination; PNFA, progressive non-fluent aphasia; PPA, primary progressive aphasias; PTA, pure tone audiometry
Received May 5, 2009. Revised July 14, 2009. Accepted August 10, 2009.