EPAD LCS

EPAD LCS is a European cohort that followed adults aged 50 or over without dementia to describe the earliest, preclinical and prodromal stages of Alzheimer's disease and to provide a pool of well-characterised people for prevention trials. It ran from 2016 to 2020 as an Innovative Medicines Initiative public-private partnership. The final data release, V.IMI (30 October 2020), holds all 2,096 participants who consented, including screen failures.

Composition

Of the participants available for analysis, about 57% are women and the mean age is about 66 years. Screening was enriched for amyloid: 37% were CSF amyloid positive at enrolment, and 358 meet criteria for preclinical Alzheimer's disease. Visits took place at baseline, 6 months and then yearly for up to three years, with MRI at every visit except the 6-month one. The release links images to cognition, CSF biomarkers, APOE genotype, demographics and vital signs. Image counts per sequence are published only for the earlier V1500.0 baseline release.

Acquisition

Baseline scans came from 21 sites with seven scanner models from Siemens, Philips and GE using a common protocol. Core sequences, run at all sites, are 3D T1w, 3D FLAIR, axial 2D T2w and axial 2D T2*-weighted gradient echo (0.9 x 0.9 x 3 mm, TE 20 ms) meant for microbleed reading. Thirteen sites with 3 T scanners added SWI with phase, resting-state fMRI, diffusion MRI and ASL. Images are offered as raw NIfTI, processed NIfTI and image-derived phenotype tables.

Annotations

A central reader (IXICO) reported radiological reads for eligibility and follow-up, including microbleed counts, lacunes and infarcts. White matter hyperintensity masks come from BaMoS segmentation of FLAIR. FreeSurfer volumes, automated quality metrics and visual quality grades of T1w images are also released. No voxel-level microbleed labels are described.

Known limitations

• Most ASL scans from older Philips software show fat-saturation artefacts and are left out of the processed data.
• Advanced sequences exist only for participants scanned at the 3 T advanced sites.
• Few participants reached the 2- and 3-year visits because the study closed in 2020.
• Ethnicity is not collected at French sites and only year of birth at Swiss sites.