AHEAD 3-45 screening data

AHEAD 3-45 is a public-private prevention study of the Alzheimer's Clinical Trials Consortium and Eisai that tests the anti-amyloid antibody lecanemab in cognitively unimpaired people. It runs two sister trials under one protocol with a shared screening process: A3 for people with intermediate brain amyloid (about 20 to 40 Centiloids) and A45 for people with elevated amyloid (above 40 Centiloids). The shared data cover the screening stage only and are meant for research on preclinical Alzheimer's disease, amyloid screening and recruitment.

Composition

The study started in July 2020 and finished enrolment in 2024 after 20,720 screens worldwide. The accessible dataset is limited to the 16,835 screens from sites in the United States and Canada, because of data sharing rules in other countries. Screening combined a blood test of the plasma amyloid-beta 42/40 ratio, cognitive testing and amyloid PET. The portal states that imaging data are available, but it does not list which scan types are included. Data after randomization are not shared.

Acquisition

About 100 sites in North America, Japan, Singapore, Australia and Europe took part, more than 70 of them in the US and Canada. Amyloid PET used only the tracer [18F]NAV4694 and tau PET only [18F]MK6240. MRI was used to check eligibility and to monitor amyloid-related imaging abnormalities during treatment; the design paper gives no sequence details.

Annotations

No image labels are described. Eligibility for A3 or A45 was decided from quantitative amyloid PET.

Known limitations

• Screening data only, and only from North American sites.
• The public pages do not list the image series, file formats, scanners or field strengths in the release.
• Participants were 55 to 80 years old at entry and cognitively unimpaired, and plasma prescreening screened out people unlikely to have elevated amyloid before they went on to PET.