1 Scientific RepoRts | 5:16404 | DOI: 10.1038/srep16404 www.nature.com/scientificreports early astrocytosis in autosomal dominant Alzheimer’s disease measured in vivo by multi-tracer positron emission tomography Michael schöll 1,2 , stephen F. Carter 1,3 , eric Westman 4 , elena Rodriguez-Vieitez 1 , ove Almkvist 1,5,6 , steinunn thordardottir 5,7 , Anders Wall 8 , Caroline Graf 5,7 , Bengt Långström 9 & Agneta Nordberg 1,5 studying autosomal dominant Alzheimer’s disease (ADAD), caused by gene mutations yielding nearly complete penetrance and a distinct age of symptom onset, allows investigation of presymptomatic pathological processes that can identify a therapeutic window for disease-modifying therapies. Astrocyte activation may occur in presymptomatic Alzheimer’s disease (AD) because reactive astrocytes surround β-amyloid (Aβ) plaques in autopsy brain tissue. positron emission tomography was performed to investigate fbrillar Aβ, astrocytosis and cerebral glucose metabolism with the radiotracers 11 C-pittsburgh compound-B (pIB), 11 C-deuterium-L-deprenyl (DeD) and 18 F-fuorodeoxyglucose (FDG) respectively in presymptomatic and symptomatic ADAD participants (n = 21), patients with mild cognitive impairment (n = 11) and sporadic AD (n = 7). Multivariate analysis using the combined data from all radiotracers clearly separated the diferent groups along the frst and second principal components according to increased PIB retention/decreased FDG uptake (component 1) and increased DED binding (component 2). Presymptomatic ADAD mutation carriers showed signifcantly higher PIB retention than non-carriers in all brain regions except the hippocampus. DeD binding was highest in presymptomatic ADAD mutation carriers. this suggests that non-fbrillar Aβ or early stage plaque depostion might interact with infammatory responses indicating astrocytosis as an early contributory driving force in AD pathology. the novelty of this fnding will be investigated in longitudinal follow-up studies. Alzheimer’s disease (AD) is a progressive brain disorder with gradually occurring cognitive decline. Te time course of the underlying pathological changes remains largely veiled. Increasing evidence argues that these changes start decades before the onset of clinical symptoms. Te order and magnitude of these processes are hitherto not well understood. Te typical histopathology of AD includes the presence of 1 Department nVS, center for Alzheimer Research, Division of translational Alzheimer neurobiology, Karolinska Institutet, 141 57 Huddinge, Sweden. 2 MedTech West and the Department of Clinical Neuroscience and Rehabilitation, University of Gothenburg, 413 45 Gothenburg, Sweden. 3 Wolfson Molecular Imaging Centre, University of Manchester, Manchester, M20 3LJ, UK. 4 Department nVS, center for Alzheimer Research, Division of Clinical Geriatrics, Karolinska Institutet, 141 57 Huddinge, Sweden. 5 Department of Geriatric Medicine, Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden. 6 Department of Psychology, Stockholm University, 106 91 Stockholm, Sweden. 7 Department nVS, center for Alzheimer Research, Division of neurogeriatrics, Karolinska Institutet, 141 57 Huddinge, Sweden. 8 Department of Surgical Sciences, Section of Nuclear Medicine & PET, Uppsala University, 751 85 Uppsala, Sweden. 9 Department of Chemistry, Uppsala University, 701 05 Uppsala, Sweden. Correspondence and requests for materials should be addressed to A.N. (email: agneta.k.nordberg@ ki.se) Received: 01 July 2015 Accepted: 13 October 2015 Published: 10 November 2015 opeN