Loss of olfactory function in dementing disease.

Area of Science:

• Neuroscience
• Gerontology
• Neurology

Background:

• Alzheimer's disease (AD) involves neuropathological changes in olfactory processing areas.
• Down syndrome (DS) patients develop AD-like brain changes by middle age.
• Olfactory dysfunction may indicate early neurodegeneration and have diagnostic value.

Purpose of the Study:

• To assess olfactory function in Alzheimer's disease (AD) and Down syndrome (DS) patients.
• To investigate olfactory changes in relation to disease progression and genetic factors (APOE4).
• To compare olfactory deficits in AD, DS, and Huntington's disease (HD).

Main Methods:

• Functional olfactory testing including threshold, identification, similarity, recognition memory, recall, and fluency.
• Longitudinal assessment of olfactory measures and cognitive decline (DRS scores).
• Comparison of olfactory performance across patient groups (AD, DS, HD) and normal controls with and without APOE4 allele.

Main Results:

• Both AD and DS patients exhibited significant olfactory impairments, varying by task and disease stage.
• Longitudinal data showed declining olfactory function correlating with cognitive decline.
• APOE4 carriers had poorer odor identification than non-carriers; HD patients also showed olfactory deficits, differing from cortical dementias.

Conclusions:

• Olfactory testing reveals significant functional impairments in AD and DS patients.
• Specific olfactory measures show promise for early detection and monitoring of neurodegenerative diseases.
• Olfactory deficits are present across various neurodegenerative conditions, with distinct patterns observed.