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Amyloid-Beta Deposition in Basal Frontotemporal Cortex Is Associated with Selective Disruption of Temporal Mnemonic
Casey R Vanderlip1, Lisa Taylor1, Soyun Kim1
1Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697.
Summary
Early amyloid-beta (Aβ) accumulation in the brain may impair temporal memory discrimination in preclinical Alzheimer's disease (AD). This suggests Aβ selectively affects temporal processing, potentially aiding early AD detection.
Area of Science:
- Neuroscience
- Neurology
- Gerontology
Background:
- Cerebral amyloid-beta (Aβ) accumulation is a key Alzheimer's disease (AD) pathology, appearing decades before symptoms.
- Subtle memory deficits in preclinical AD are not fully understood, and Aβ's specific impact on memory domains is unclear.
- Mnemonic discrimination, crucial for episodic memory, involves distinct neural circuits that may be differentially affected by Aβ deposition.
Purpose of the Study:
- To investigate whether specific domains of mnemonic discrimination are selectively impaired by early cerebral amyloid-beta (Aβ) deposition in cognitively unimpaired older adults.
- To explore the association between Aβ positron emission tomography (Aβ-PET) levels and deficits in object, spatial, and temporal mnemonic discrimination.
- To identify brain regions where Aβ accumulation correlates with specific mnemonic discrimination deficits, particularly in temporal processing.
Main Methods:
- 108 cognitively unimpaired older adults underwent 18F-florbetapir positron emission tomography (Aβ-PET) scanning.
- Participants completed a battery of mnemonic discrimination tasks assessing object, spatial, and temporal domains.
- A control group of 35 young adults was included for comparison.
Main Results:
- A dissociation was observed: object and spatial mnemonic discrimination showed general age-related deficits.
- Amyloid-beta positron emission tomography (Aβ-PET) levels were selectively associated with deficits in temporal mnemonic discrimination.
- Higher Aβ-PET levels in the medial orbitofrontal and inferior temporal cortex correlated with greater temporal mnemonic discrimination deficits.
Conclusions:
- Amyloid-beta (Aβ) accumulation in basal frontotemporal regions may selectively disrupt temporal mnemonic discrimination in preclinical Alzheimer's disease (AD).
- These findings highlight the selective vulnerability of temporal processing circuits to early Aβ deposition.
- Assessing temporal mnemonic discrimination could potentially aid in predicting emerging AD progression.
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