Abstract Body

Astrocytes in brain play an important role in maintaining an optimal brain function including direct regulation of synapse activity and via cross talks between glia and neurons. The respond of astrocytes to changes in brain homoeostasis are observed by defence processes named reactive astrogliosis. An increased astrogliosis is detected by PET imaging in early stages of AD as well in other non-AD dementia such as frontotemporal dementia. Reactive astrocytes seem to be closely related to both amyloid and tau in brain but also to cerebral metabolisms and microstructures, . PET data suggest that high levels of reactive astrogliosis in early presymptomatic stages of AD may precede some other pathological hallmarks of AD. Ongoing PET studies in autosomal dominant and sporadic AD individuals aim to investigate whether astrogliosis are driving the propagation of tau during disease progression with cognitive decline. Our translational in vivo / in vitro tracer imaging studies suggest the presence of ” a first and a second wave” of reactive astrogliosis in AD and with different relationship with other AD pathology biomarkers at the different stages of the disease. New promising PET tracers for visualizing reactive astrogliosis in brain provide further valuable insight to disease mechanisms for both AD and other non-AD dementia. The clinical value of new fluid astrocytes biomarkers and their relationship to brain astrogliosis as well as to other fluid and brain biomarkers represent new avenues which presently are under exploration and also might be provide new tools for evaluation of new drug targets.