O2‐09‐06: TRAJECTORY OF LOBAR ATROPHY IN ASYMPTOMATIC AND SYMPTOMATIC GRN MUTATION CARRIERS: A LONGITUDINAL TBM‐SYN STUDY

neuropsychology testing and volumetric MRI scans. All participants were at 50% risk of carrying a pathogenic FAD mutation. Standardized uptake value ratios (SUVr) in prespecified regions of interest (ROI) (Braak stages I-VI) were obtained using cerebellar grey matter as the reference region. We compared tau PETaccumulation rates between mutation carriers (MC) and non-carriers (NC). Results: The cohort comprised three NC and sixMC; one symptomatic (Clinical Dementia Rating (CDR) Scale:0.5 and five presymptomatic (CDR:0). MCs were on average 9.2 years younger than their parental age at symptom onset. Presymptomatic MC did not appear to have greater FTP binding or rates of change compared to NC (Figure 1). In one symptomatic MC higher tau signal, and rates of accumulation, were seen across all Braak stage ROIs (Figure 1). Conclusions: Our small cohort could not detect differences in tau accumulation between presymptomatic MC and NC. However, there was widespread and rapid increases in FTP binding (Braak Stage ROIs I-VI) at the time of symptom onset in one MC. Longitudinal tau PET scanning may be useful in tracking progression in mildly symptomatic FAD.