Abstract
The cognition of nonverbal sounds in dementia has been relatively little explored. Here we undertook a systematic study of nonverbal sound processing in patient groups with canonical dementia syndromes comprising clinically diagnosed typical amnestic Alzheimer's disease (AD; n=21), progressive nonfluent aphasia (PNFA; n=5), logopenic progressive aphasia (LPA; n=7) and aphasia in association with a progranulin gene mutation (GAA; n=1), and in healthy age-matched controls (n=20). Based on a cognitive framework treating complex sounds as ‘auditory objects’, we designed a novel neuropsychological battery to probe auditory object cognition at early perceptual (sub-object), object representational (apperceptive) and semantic levels. All patients had assessments of peripheral hearing and general neuropsychological functions in addition to the experimental auditory battery. While a number of aspects of auditory object analysis were impaired across patient groups and were influenced by general executive (working memory) capacity, certain auditory deficits had some specificity for particular dementia syndromes. Patients with AD had a disproportionate deficit of auditory apperception but preserved timbre processing. Patients with PNFA had salient deficits of timbre and auditory semantic processing, but intact auditory size and apperceptive processing. Patients with LPA had a generalised auditory deficit that was influenced by working memory function. In contrast, the patient with GAA showed substantial preservation of auditory function, but a mild deficit of pitch direction processing and a more severe deficit of auditory apperception. The findings provide evidence for separable stages of auditory object analysis and separable profiles of impaired auditory object cognition in different dementia syndromes.
Highlights
Rivastigmine 6mg b.d. Memantine 10mg b.d. Donepezil 5mg nocte
Background neuropsychologyPIQ BPVS RMT RMT Naming Arithmetic Object decision Stroop StroopStroopDigit span
Six key cerebral regions implicated in auditory processing (Heschl's gyrus, planum temporale, superior temporal gyrus anterior to Heschl's gyrus, inferior temporal lobe, mesial temporal lobe, parietal lobe) were rated as either: unaffected; atrophied bilaterally with no strong asymmetry (+); atrophied bilaterally with more severe damage in the left or right hemisphere (L or R)
Summary
Rivastigmine 6mg b.d. Memantine 10mg b.d. Donepezil 5mg nocte
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