Supplementary data

HC = healthy control, Stable = Did not develop dementia, Convert = Developed dementia at 1 year. Age_at_scan_years: Age at assessment/scan Age_base: Age as study entry time_btw_scans_years: Time between scans measured in years. Female: 0 = male, 1 = female Education: years of education FU_1year: 1 st or 2 nd scan time: assessment time, either baseline (study entry) or follow up (~ 1year). time.y : time, in years, of follow up.

GM_order.diff.and.avg : Subject order of the 4D files associated with grey matter (swarate_GM_44.nii.gz, swavg_GM_44.nii.gz). Exclude.motion.T1: T1 images excluded due to motion at Y0 or Y1. TBSS_order.diff.and.avg: Order of the 4D image files associated with DTI and TBSS.

ASL_order.diff: Subject order of the 4D image file (sdiff_wecqCBF_43.nii.gz:). ASL_order_avg.part1 : Subject order of the 4D image files (demeaned_swecqCBF_43_base_part1.nii.gz, savg_wecqCBF_43_part1.nii.gz). ASL_order_avg.part2 : Subject order of the 4D image files (demeaned_swecqCBF_43_base_part2.nii.gz, savg_wecqCBF_43_part2.nii.gz).

SIENA: % brain change between scans. Values only at baseline (first timepoint). DTI relative motion: average relative motion between adjacent diffusion volumes (see manuscript for details). mean FA/MD/L1/RD: mean FA /MD/L1/RD values along the white matter skeleton CBF_gm: mean grey matter perfusion (ml/100g/min), including cortex and subcortical grey. diff.FA.Y0-Y1 (same for MD/CBF): raw difference between mean FA at Y0 and Y1. per.diff.FA.Y0-Y1 (same for MD/CBF): percent difference between mean FA at Y0 and Y1. per.diff.year.FA.Y0-Y1 (same for MD/CBF): percent difference between mean FA at Y0 and Y1, divided by the time between Y0 and Y1.

MoCa: Montreal cognitive assessment—global cognitive screen. UPDRS Part 3: Unified Parkinson’s disease rating scale, part 3, the motor score (only scores for PD participants). LED: Levodopa equivalent dose.

Attention Total: average z score for tests in the domain of attention, working memory, and processing speed. Executive Function Total: average z score for tests in the domain of executive function. Visuo-Total: average z score for tests in the domain of visuospatial/visuoperceptual function.

Language all Domains: average z score for tests in the domain of Language. Total all Domains: global cognitive score: average z score for the domain scores (attention, executive function, learning & memory, and visuospatial/perceptual)