POINTER Imaging

POINTER Imaging is the neuroimaging ancillary study of U.S. POINTER, a two-year randomized trial run by the Alzheimer's Association that compares a self-guided and a structured multidomain lifestyle intervention (nutrition, exercise, cognitive and social stimulation, health monitoring) in older adults at risk of cognitive decline. The imaging study, led from UC Berkeley and funded by the National Institute on Aging, asks whether amyloid, tau, hippocampal volume and white matter hyperintensities at baseline predict the cognitive response to the intervention, and whether the intervention changes these markers. Images are distributed through the LONI Image and Data Archive after an approved data use application.

Composition

Imaging enrollment ran from August 2020 to March 2023 and took in 1052 of the 2111 trial participants, recruited around five sites in Northern California, North Carolina, Chicago, Houston and Rhode Island. Trial participants were 60 to 79 years old, sedentary, on a suboptimal diet and without significant cognitive impairment; the imaging cohort has a mean age of 68.4 years, 63% women and 31% from underrepresented ethnoracial groups. Sixty-eight enrollees withdrew before any scan. At baseline 937 had amyloid PET, of whom 271 were amyloid positive.

Acquisition

PET used [18F]florbetaben for amyloid and [18F]MK-6240 for tau, each acquired 90 to 110 minutes after injection on GE, Siemens or Philips scanners, at baseline and after two years. MRI ran on Siemens 3T systems at baseline, year 1 and year 2: 3D MPRAGE following the ADNI3 protocol, 3D FLAIR, diffusion-weighted imaging, arterial spin labeling at three sites and a three-echo T2* gradient echo. Baseline counts are 962 T1-weighted, 958 FLAIR, 962 T2*, 692 diffusion, 526 ASL, 937 amyloid and 923 tau scans.

Annotations

No voxel-level annotations are described. Microbleeds and superficial siderosis were rated visually on the T2* images and confirmed by neuroradiologists, and the study team derived amyloid status, regional tau, hippocampal and white matter hyperintensity volumes, diffusion and blood flow measures.

Known limitations

• The data use agreement warns that processed data may be preliminary and change between versions.
• Imaging participants differ from the rest of the trial: more men and higher cardiovascular risk.
• Diffusion and ASL parameters differ by site, and two sites have no ASL.
• Follow-up scan counts are not yet published.