[Impaired Recognition of Environmental Sounds in Patients with Dementia : I can Hear but I do Not Understand]

Background: Impairment of central auditory processing is a well-known symptom of neurodegenerative dementia; however, whilst numerous studies have examined verbal processing impairment, to date few have attempted to describe impairments of non-verbal, environmental sound recognition in patients with dementia. As these impairments may have direct implications on patient support and care, such studies are urgently necessary.

Aim Of The Study: The aim of the study was to determine whether the recognition of meaningful environmental sounds is impaired in patients with mild or early stage neurodegenerative dementia.

Patients And Methods: We developed a test of non-verbal sound recognition consisting of 16 sound sequences from the familiar and unfamiliar environments. We included 18 patients with mild cognitive impairment and mild dementia caused by Alzheimer's disease and frontotemporal dementia, as well as 20 cognitively healthy controls.

Results: Patients and controls were given the test of recognizing 16 meaningful sounds from the familiar and unfamiliar environments. Patients with dementia performed significantly worse in comparison to cognitively healthy controls. Whilst healthy controls correctly recognized on average 12.1 ± 2.2 out of 16 sounds, cognitively impaired patients recognized 9.2 ± 2.5. Correlation analysis showed that the mini mental state examination (MMSE) scores were positively correlated with the number of correctly recognized sounds (MMSE: r = 0.556, p = 0.017).

Discussion: The fact that even in mild stages of Alzheimer's disease or frontotemporal dementia patients either do not recognize or misinterpret environmental sounds must be taken into consideration not only in everyday life but in particular when patients need to leave their familiar living environment, whether temporarily (e. g. hospitalization) or permanently (e. g. nursing home admission).