an at risk stage of AD, is still poorly studied with respect to microstructural brain changes. In this study, we present first results from a multicenter DTI study using tract-based spatial statistics. Methods: We investigated FA, MD and MO in a multicentric sample of 172 participants consisting of individuals with AD, mild cognitive impairment (MCI), and SCD who were recruited in the DELCODE study, a prospective longitudinal observational study. DTI data were acquired at six sites, using homogeneous scanning parameters and protocols. We performed tract-based spatial statistics to determine alterations of FA, MD and MO in the white matter (WM). Results:In comparison to the control group, FA in the SCD group was significantly decreased in the right inferior fronto-occipital fasciculus (IFOF), bilateral corticospinal tract, bilateral internal capsule (posterior limb), and right anterior thalamic radiation (ATR; p < .05, corrected for multiple comparisons). Moreover, significant increases in MO for the AD group relative to controls was found in right IFOF and ATR. While no effect of MD emerged, trends of decreased MO in all groups compared to controls were detected in various WM regions, including the body and splenium of the corpus callosum, left anterior limb of the external capsule, as well as cingulum. Conclusions:FA and MO of controls were significantly different compared to SCD and AD, respectively. MO showed a consistent trend between all patient groups and controls in a wide range of brain tracts. In the larger DELCODE sample still to come we will include the association of DTI changes with amyloid status and cognitive decline in people with SCD. These data will help to establish the potential use of DTI as an early indicator of prodromal AD in at risk populations.