Neuroinflammation in Neurodegenerative Disorders—a Review

The potential for positron emission tomography (PET) to detect neuroinflammation in vivo has sparked a remarkable interest in various disciplines of neuroscience. Early PET radioligands, such as [11C]PK(R)-11195 for the 18-kDa translocator protein (TSPO) and [11C]L-deprenyl for monoamine oxidase B, have been used in studies designed to clarify the role of neuroinflammation in a variety of psychiatric and neurological disorders. Recent years have witnessed the development of several second-generation PET radioligands for TSPO and radioligands to measure endogenous targets that are active in various stages of the inflammatory cascade, such as cyclooxygenase and arachidonic acid. Here, we discuss some of the biomarkers for neuroinflammation that are available for quantification with PET, as well as recent findings from studies where neuroinflammation has been assessed in neurodegenerative disorders. In addition, we highlight the challenges to accurate interpretation of PET studies of neuroinflammation.