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Systemic infection, interleukin 1beta, and cognitive decline in Alzheimer's disease
C Holmes1, M El-Okl, A L Williams
1School of Medicine and Biological Sciences, University of Southampton, Southampton, UK. ch4@soton.ac.uk
Abstract:
Activated microglia, the resident macrophages of the brain, are a feature of Alzheimer's disease. Animal models suggest that when activated microglia are further activated by a subsequent systemic infection this results in significantly raised levels of interleukin 1beta within the CNS, which may in turn potentiate neurodegeneration. This prospective pilot study in Alzheimer's disease subjects showed that cognitive function can be impaired for at least two months after the resolution of a systemic infection and that cognitive impairment is preceded by raised serum levels of interleukin 1beta. These relations were not confounded by the presence of any subsequent systemic infection or by baseline cognitive scores. Further research is needed to determine whether recurrent systemic infections drive cognitive decline in Alzheimer's disease subjects through a cytokine mediated pathway.
Insights
Systemic infections worsen cognitive decline in Alzheimer's disease (AD) patients for months. This cognitive impairment is linked to elevated interleukin-1beta levels, suggesting a cytokine-mediated pathway driving neurodegeneration in AD.
Area of Science:
- Neuroscience
- Immunology
- Gerontology
Background:
- Activated microglia are implicated in Alzheimer's disease (AD) pathology.
- Systemic infections may exacerbate neuroinflammation and neurodegeneration in AD via cytokine pathways, as suggested by animal models.
Purpose of the Study:
- To investigate the impact of systemic infections on cognitive function in AD patients.
- To explore the relationship between cognitive impairment, interleukin-1beta levels, and systemic infections in AD.
Main Methods:
- Prospective pilot study involving Alzheimer's disease subjects.
- Monitoring of cognitive function and serum levels of interleukin-1beta following systemic infections.
Main Results:
- Cognitive function remained impaired for at least two months post-infection resolution in AD subjects.
- Elevated serum interleukin-1beta levels preceded cognitive impairment.
- These findings were independent of subsequent infections or baseline cognitive scores.
Conclusions:
- Systemic infections can lead to prolonged cognitive impairment in Alzheimer's disease patients.
- Interleukin-1beta may mediate the link between systemic infections and cognitive decline in AD.
- Further research is warranted to confirm the role of recurrent infections and cytokine pathways in AD progression.