FDG-PET and amyloid-PET imaging: the diverging paths

Area of Science:

• Neuroimaging
• Molecular Biology
• Neuropathology

Background:

• Alzheimer's disease (AD) diagnosis and clinical trials face challenges due to in-vivo assessment tools for metabolic dysfunction and amyloid burden.
• Positron emission tomography (PET) neuroimaging, including amyloid-PET and fluorodeoxyglucose-PET (FDG-PET), provides critical molecular insights into AD.
• Neuropathological hallmarks of AD, such as senile plaques and neurofibrillary tangles, are targets for therapeutic interventions and in-vivo imaging biomarkers.

Purpose of the Study:

• To review the distinct molecular information provided by amyloid-PET and FDG-PET in Alzheimer's disease.
• To highlight the diverging molecular pathways in AD progression.
• To explore new research and clinical applications for PET imaging in AD.

Main Methods:

• Review of existing literature on PET neuroimaging in Alzheimer's disease.
• Analysis of molecular information from amyloid-PET and FDG-PET.
• Examination of current understanding of AD pathophysiology and its relation to PET biomarkers.

Main Results:

• PET imaging reveals that Alzheimer's disease progression involves distinct, potentially parallel, molecular pathways.
• Neuronal injury biomarkers and tau pathology can be independent of beta-amyloid (Aβ) deposition, challenging the 'amyloid cascade hypothesis'.
• Amyloid and neuronal injury pathways may diverge and relate differently to AD symptoms and clinical phenotypes.

Conclusions:

• The molecular events in AD, including Aβ and tau deposition, neuronal injury, and neurodegeneration, can occur in parallel.
• Diverging amyloid and neuronal injury pathways have implications for AD diagnosis and drug development.
• Understanding these parallel paths is crucial for developing novel therapeutic strategies to slow or prevent dementia.