Impairments of auditory scene analysis in posterior cortical atrophy

Abstract

Although posterior cortical atrophy is often regarded as the canonical ‘visual dementia’, auditory symptoms may also be salient in this disorder. Patients often report particular difficulty hearing in busy environments; however, the core cognitive process—parsing of the auditory environment (‘auditory scene analysis’)—has been poorly characterized. In this cross-sectional study, we used customized perceptual tasks to assess two generic cognitive operations underpinning auditory scene analysis—sound source segregation and sound event grouping—in a cohort of 21 patients with posterior cortical atrophy, referenced to 15 healthy age-matched individuals and 21 patients with typical Alzheimer’s disease. After adjusting for peripheral hearing function and performance on control tasks assessing perceptual and executive response demands, patients with posterior cortical atrophy performed significantly worse on both auditory scene analysis tasks relative to healthy controls and patients with typical Alzheimer’s disease (all P < 0.05). Our findings provide further evidence of central auditory dysfunction in posterior cortical atrophy, with implications for our pathophysiological understanding of Alzheimer syndromes as well as clinical diagnosis and management.

Primary Progressive Aphasia: Toward a Pathophysiological Synthesis

“…One parsimonious explanation for the phonemic errors made in speech output in lvPPA is that these relate to a general impairment in phonemic representation, though the association between phonemic input and output errors is yet to be explored experimentally. Patients with lvPPA also show pronounced difficulties understanding degraded speech [52••], which may reflect a more general deficit in terms of parsing the auditory environment ('auditory scene analysis')-this has not been tested experimentally but accords with findings in typical Alzheimer's disease and posterior cortical atrophy (a visuospatial form of Alzheimer's disease) suggesting that damage to posteromedial cortices may underpin these deficits across the AD spectrum [79,80].…”

Processing of Degraded Speech in Brain Disorders

“…During the perception of their own name over background babble (the classical “cocktail party effect”), patients with AD were shown to have abnormally enhanced activation relative to healthy older controls in right supramarginal gyrus [ 90 ]. Auditory scene analysis deficits are most striking in posterior cortical atrophy, the variant AD syndrome led by visuo-spatial impairment, further suggesting that posterior cortical regions within the core temporo-parietal network targeted by AD pathology play a critical pathophysiological role [ 198 ]. Speech-in-noise processing deficits may precede the onset of other symptoms in AD and may be a prodromal marker [ 199 , 200 , 201 ].…”

A systematic review of atypical Alzheimer's disease including behavioural and psychological symptoms

“…Uncommonly, patients may present as Gerstmann syndrome (acalculia, right–left disorientation, agraphia, and finger agnosia) 66,67 . PCA patients also experience difficulty in hearing in busy environments because of a problem with sound source segregation and sound event grouping 74 . Dyslexia could occur because of an inability to recognize words or an inability to generate eye movements from word to word or from one sentence line to the next resulting in comprehension difficulties 66,67 .…”

“…66,67 PCA patients also experience difficulty in hearing in busy environments because of a problem with sound source segregation and sound event grouping. 74 Dyslexia could occur because of an inability to recognize words or an inability to generate eye movements from word to word or from one sentence line to the next resulting in comprehension difficulties. 66,67 They may also have ideomotor apraxia in which patients are unable to pantomime the use of tools, for example brushing one's teeth.…”