Visual and Auditory Sensory Impairments Differentially Relate with Alzheimer's Pathology

Area of Science:

• Neuroscience
• Gerontology
• Ophthalmology
• Audiology

Background:

• Sensory impairments, including visual sensory impairment (VSI) and auditory sensory impairment (ASI), are common in older adults.
• These impairments have been anecdotally linked to cognitive decline, but the underlying neuropathological mechanisms remain unclear.
• Investigating the relationship between sensory deficits and specific brain pathologies is crucial for understanding cognitive aging.

Purpose of the Study:

• To investigate the association between VSI and ASI and brain pathological changes, specifically beta-amyloid (Aβ) deposition and brain atrophy, in cognitively unimpaired older adults.
• To determine if these sensory impairments predict future AD pathology or brain structural changes over a 2-year period.
• To differentiate the neuropathological correlates of VSI versus ASI in the context of cognitive aging.

Main Methods:

• Cross-sectional and longitudinal analyses were conducted on cognitively unimpaired older adults.
• VSI and ASI were assessed at baseline using self-report questionnaires.
• Brain [11C]Pittsburgh Compound B PET scans assessed Aβ deposition, MRI evaluated brain structure and white matter hyperintensity volume, and clinical assessments were performed at baseline and 2-year follow-up.

Main Results:

• VSI was significantly associated with higher baseline Aβ deposition and increased Aβ deposition over 2 years.
• VSI was also linked to greater atrophy in AD-related brain regions over the follow-up period.
• No significant associations were found between ASI and Aβ deposition, brain atrophy, or cerebrovascular injury.

Conclusions:

• VSI is likely associated with Alzheimer's disease-specific pathological changes (Aβ deposition and atrophy), potentially mediating its link to cognitive decline.
• ASI does not appear to be associated with AD pathologies but may contribute to cognitive decline through alternative mechanisms.
• These findings highlight the distinct neuropathological pathways through which different sensory impairments may influence cognitive aging.