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Preserved stimulus deviance detection in Alzheimer's disease
E Pekkonen1, L P Jääskeläinen, T Erkinjuntti
1Department of Neurology, University of Helsinki, and Medical Engineering Centre, Helsinki University Central Hospital, Finland.
Neuroreport
|June 21, 2001
Summary
Aging impairs auditory discrimination to duration changes, but this automatic process may be preserved in early Alzheimer's disease (AD). Magnetic mismatch negativity (MMNm) showed delayed responses in the left hemisphere of AD patients, not attenuated discrimination.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Cognitive Neuroscience
Background:
- Aging typically impairs automatic auditory discrimination, particularly to duration changes.
- Frequency change detection remains relatively intact in aging and Alzheimer's disease (AD).
- The impact of AD on auditory duration discrimination is not fully understood.
Purpose of the Study:
- To investigate if cortical auditory discrimination to duration change, measured by magnetic mismatch negativity (MMNm), is impaired in individuals with Alzheimer's disease (AD).
Main Methods:
- Utilized a whole-head magnetometer to record MMNm responses.
- Presented frequent standard tones with occasional shorter duration deviants monaurally.
- Compared MMNm in 20 AD patients (mild to moderate impairment) and 18 age-matched healthy controls.
Main Results:
- MMNm showed a significant delay in the left hemisphere, ipsilateral to the stimulated ear, in the AD patient group.
- MMNm amplitudes were comparable between AD patients and healthy controls across both hemispheres.
- These findings suggest preserved automatic auditory discrimination in the early stages of AD.
Conclusions:
- Cortical auditory discrimination to duration change, as indicated by MMNm, is not attenuated in the early stages of Alzheimer's disease.
- A delay in MMNm in the left hemisphere suggests potential subtle processing alterations rather than a complete deficit.