Does Microglial Activation Influence Hippocampal Volume and Neuronal Function in Alzheimer's Disease and Parkinson's
Grazia D Femminella1, Siddharth Ninan1, Rebecca Atkinson1
1Neurology Imaging Unit, Imperial College London, London, UK.
Background:
The influence of neuroinflammation on neuronal function and hippocampal atrophy in Alzheimer's disease (AD) and Parkinson's disease dementia (PDD) is still unclear.
Objectives:
Here we investigated whether microglial activation measured by [11C]PK11195 PET is associated with neuronal function measured by cerebral glucose metabolic rate (rCMRGlc) using FDG-PET and hippocampal volume measurements.
Methods:
We enrolled 25 subjects (9 PDD, 8 AD, and 8 controls) who underwent PET scans with [11C](R)PK11195, [18F]FDG, and volumetric MRI scanning.
Results:
SPM correlation analysis in AD and PDD showed a negative correlation between hippocampal volume and microglial activation within hippocampus or parahippocampus and with cortical and subcortical areas of projections from hippocampus, while there was a positive correlation between rCMRGlc in cortical and subcortical areas of projections from hippocampus and hippocampal volume. Hippocampal volume was significantly reduced in AD compared to controls but not in PDD.
Conclusions:
These findings indicate that microglial activation inversely correlated with hippocampal volume and hippocampal rCMRGlc in neurodegenerative diseases with dementia, providing further evidence for the central role of microglial activation in neurodegenerative diseases.
Insights
Neuroinflammation, measured by microglial activation, is linked to reduced hippocampal volume and function in Alzheimer's disease (AD) and Parkinson's disease dementia (PDD). This highlights neuroinflammation's key role in these neurodegenerative conditions.
Area of Science:
- Neuroscience
- Neurology
- Medical Imaging
Background:
- The impact of neuroinflammation on neuronal function and hippocampal atrophy in Alzheimer's disease (AD) and Parkinson's disease dementia (PDD) remains incompletely understood.
- Microglial activation is a key indicator of neuroinflammation.
Purpose of the Study:
- To investigate the association between microglial activation, neuronal function (cerebral glucose metabolic rate - rCMRGlc), and hippocampal volume in AD and PDD.
- To utilize Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) for comprehensive assessment.
Main Methods:
- Enrolled 25 participants: 9 with PDD, 8 with AD, and 8 healthy controls.
- Conducted PET scans using [11C](R)PK11195 (for microglial activation) and [18F]FDG (for rCMRGlc).
- Performed volumetric MRI scans to measure hippocampal volume.
Main Results:
- A negative correlation was observed between hippocampal volume and microglial activation in AD and PDD patients.
- Hippocampal volume was significantly reduced in AD patients compared to controls, but not in PDD patients.
- Positive correlation found between hippocampal volume and rCMRGlc in related cortical and subcortical areas.
Conclusions:
- Microglial activation inversely correlates with hippocampal volume and function in neurodegenerative diseases with dementia.
- These findings underscore the significant role of microglial activation in the pathophysiology of neurodegenerative diseases like AD and PDD.
