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Published on: December 26, 2016
Microglial responses partially mediate the effect of Aβ on cognition in Alzheimer's disease
Lasse S Madsen1, Rola Ismail2, Peter Parbo3
1Department of Clinical Medicine, Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark.
Introduction:
Microglial responses are an integral part of Alzheimer's disease (AD) pathology and are associated with amyloid beta (Aβ) deposition. This study aimed to investigate the effects of Aβ and microglial responses on global cognitive impairment.
Methods:
In this longitudinal study, 28 patients with mild cognitive impairment and 11 healthy controls underwent 11C-PK11195 and 11C-Pittsburgh compound B positron emission tomography (PET), structural magnetic resonance imaging scans, and global cognitive ratings at baseline and 2-year follow-up. Correlations between PET uptake and global cognition were assessed. Additionally, the mediation effect of the microglial response on the association between Aβ load and global cognition was assessed.
Results:
Aβ load and the microglial response were both independently detrimental to global cognitive performance at baseline; however, at 2-year follow-up the association between Aβ load and global cognitive ratings was partially mediated by the microglial response.
Discussion:
As AD progresses, the associated microglial response partially mediates the detrimental effect of aggregated Aβ on cognition.
Highlights:
This was a longitudinal study of amyloid beta (Aβ), microglial responses, and global cognitive performance. Aβ and microglial responses both affect cognition in early Alzheimer's disease. Microglial response partially mediates the effect of Aβ on cognition in later stages.
Insights
In Alzheimer's disease, amyloid beta (Aβ) and microglial responses independently harm cognition. Over time, microglial responses partially mediate Aβ's negative impact on cognitive function.
Area of Science:
- Neuroscience
- Neurology
- Alzheimer's Disease Research
Background:
- Microglial activation is a key component of Alzheimer's disease (AD) pathology, closely linked to amyloid beta (Aβ) accumulation.
- Investigating the interplay between Aβ, microglial responses, and cognitive decline is crucial for understanding AD progression.
Purpose of the Study:
- To examine the longitudinal effects of amyloid beta (Aβ) deposition and microglial responses on global cognitive impairment in patients with mild cognitive impairment.
- To determine if microglial responses mediate the relationship between Aβ load and cognitive decline over a 2-year period.
Main Methods:
- Longitudinal study involving 28 mild cognitive impairment patients and 11 healthy controls.
- Utilized positron emission tomography (PET) with 11C-PK11195 and 11C-Pittsburgh compound B, structural MRI, and cognitive assessments at baseline and 2-year follow-up.
- Statistical analyses assessed correlations between PET uptake, cognitive ratings, and the mediation effect of microglial response on the Aβ-cognition association.
Main Results:
- Both amyloid beta (Aβ) load and microglial response were independently associated with poorer global cognitive performance at baseline.
- At the 2-year follow-up, the association between Aβ load and global cognition was partially mediated by the microglial response.
- This indicates a dynamic interaction where microglial activity influences how Aβ impacts cognition over time.
Conclusions:
- Microglial responses play a significant role in mediating the neurotoxic effects of amyloid beta (Aβ) on cognition as Alzheimer's disease progresses.
- These findings highlight the microglial response as a potential therapeutic target for mitigating cognitive decline in AD.
- The study underscores the importance of considering neuroinflammation in the context of Aβ pathology for understanding and treating Alzheimer's disease.
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