The role of positron emission tomography imaging in understanding Alzheimer’s disease

Abstract

PET is a non-invasive imaging technique which allows the visualization and quantification of molecular processes, offering sensitive and early disease detection. Alzheimer’s disease (AD) is a progressive neurodegenerative disorder leading to memory loss and other functional impairments. By employing different tracers targeting neurodegeneration, amyloid and tau aggregates, cholinergic neurotransmission, neuroinflammation and other processes, PET imaging enhances our understanding of the potential triggers of AD, the chronology of molecular events in AD, the detection of early AD, differentiation of AD dementia from other dementia disorders and the development of better drugs to treat AD. As such, PET imaging at different disease stages (asymptomatic, prodromal and dementia stages) is on its way to becoming a valuable routine clinical biomarker and a drug testing and research tool in AD.

Keywords:

• Alzheimer’s disease
• amyloid
• mild cognitive impairment
• nicotine
• positron emission tomography
• tau

Financial & competing interests disclosure

H Barthel and O Sabri have served as consultants and received honoraria and travel expenses from Bayer Healthcare and Piramal Imaging. J Seibyl has served as a consultant to Pirimal Imaging, Navidea Biopharmaceuticals and GE Healthcare, and has equity in Molecular Neuroimaging. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• Alzheimer imaging by PET has recently gained increased interest mainly due to newly developed amyloid and tau tracers.

• PET imaging of amyloid has provided insights into the nature and time course of brain amyloid accumulation.

• PET detection of brain amyloid has consistently been demonstrated to be either indicative or prognostic of future cognitive impairment, although longitudinal studies remain to be performed in healthy populations in particular.

• Genotypes resulting in greater brain amyloid burden have been studied with amyloid PET to confirm the phenotype; greater PET standard uptake value ratio scores are associated with cognitive impairment.

• Especially for more holistic disease severity evaluation, estimation of glucose consumption by PET imaging using [¹⁸F]fluorodeoxyglucose and (in the future) tau PET imaging are valuable add-ons to amyloid imaging.

• Amyloid (and potentially in the future tau, neuroinflammation, cholinergic neurotransmission) PET imaging is a valuable tool to improve Alzheimer drug testing, mainly as eligibility criterion for patient inclusion and for therapy monitoring.

Notes