Speech-In-Noise Perception in Alzheimer's Disease and Primary Progressive Aphasia

Area of Science:

• Neuroscience
• Audiology
• Cognitive Science

Background:

• Understanding speech in noisy environments is crucial for communication but requires significant neural processing.
• This ability is potentially vulnerable to neurodegenerative diseases, especially those involving communication deficits like primary progressive aphasia (PPA).
• The specific impact of PPA and Alzheimer's disease (AD) on speech-in-noise perception remains unclear.

Purpose of the Study:

• To investigate how speech-in-noise perception is affected in patients with Alzheimer's disease and different subtypes of primary progressive aphasia.
• To identify the neuroanatomical correlates of impaired speech-in-noise perception in these patient groups.

Main Methods:

• The study included 59 patients with AD and PPA (logopenic, nonfluent/agrammatic, semantic variants) and 24 healthy older controls.
• Speech-in-noise perception was assessed using a digit triplet test.
• Brain MRI scans were analyzed using voxel-based morphometry to correlate speech perception with grey matter atrophy.

Main Results:

• Patients with AD, logopenic PPA, and nonfluent PPA performed significantly worse on speech-in-noise perception compared to controls, even after accounting for age, hearing, and general cognition.
• The nonfluent PPA and AD groups also exhibited poorer peripheral hearing function.
• Impaired speech-in-noise perception was associated with grey matter atrophy in the right supramarginal gyrus.

Conclusions:

• Central (brain) and peripheral hearing impairments can help differentiate major dementia types.
• These findings have implications for diagnosing dementia and developing interventions to enhance communication for individuals with dementia.