HEAD Cohort

March 31, 2025: Please refer to the Notice on the Home page.

Description of the HEAD Cohort

The HEAD study has enrolled N=749 individuals, including young healthy controls, individuals who are cognitively unimpaired, individuals with mild cognitive impairment, and individuals with AD dementia.

Cross-sectional (baseline) data collection in the HEAD study is currently completed. Longitudinal (18-month) data collection is currently ongoing at performance sites. At all HEAD study visits, the following data collection procedures are performed:

Cognitive and Health Assessments: Assessments are harmonized with the National Alzheimer’s Coordinating Center’s (NACC) Uniform Data Set (UDS) Visit Battery (version 3.0, currently transitioning to version 4.0 at most performance sites). Further assessments include the Mini-Mental State Examination (MMSE) as well as measures of socioeconomic status, female reproductive health, and adult ADHD symptoms.

Collection of Biological Samples: The National Centralized Biorepository for Alzheimer's Disease and Related Dementias (NCRAD) provides the blood collection protocols and biorepository service for HEAD study biological samples. Whole blood is collected and processed into various components including serum, plasma, and buffy coat fractions.

Neuroimaging Data:
- Collection of MR and PET imaging data is performed at specialized imaging centers at each site. All imaging data is deposited into a dedicated study database at the Laboratory of Neuroimaging (LONI).
- MRI Scans: All participants undergo 3T MRI scans following complete ADNI4 acquisition protocols, including MPRAGE, FLAIR, multi-echo GRE, rsfMRI, DTI, and ASL sequences.
- PET Scans: Amyloid and head-to-head tau PET data are collected in all participants with the following tracers with the respective acquisition windows:
  - Amyloid PET with [11C]PiB (40-60 or 50-70 min), [18F]NAV4694 (40-70 min), Neuraceq, or [18F]Flutemetamol (90-110 min).
  - Tau PET with [18F]Flortaucipir (80-100 min).
  - Tau PET with [18F]MK-6240 (90-110 min).
  - Tau PET with [18F]PI-2620 (45-75 min; subset of participants, N=175).
  - Tau PET with [18F]RO948 (70-90 min; subset of participants, N=175).

Progression of the HEAD study cohort

From the initiation of the study in November 2022 to May 2025 (30 months), participating sites in HEAD have cumulatively enrolled N=749 participants across all study groups. This enrollment effort surpassed our proposed target population for this study (N=620) by 20%.

Currently, enrolled participants have undergone clinical assessment, MRI acquisition, blood collection, amyloid PET imaging, and head-to-head tau PET imaging with at least 2 tau PET tracers (MK-6240 and Flortaucipir). Overall, N=740 participants have completed all baseline PET/MR imaging. A growing subset of participants, currently 22% of the HEAD population (N=165), have undergone head-to-head tau PET with four tau PET tracers, including additional agents PI-2620 and RO948.

All participants are currently returning for longitudinal 18-month follow-up visits at which all of the above procedures will be repeated.

Learn more about our current progress in data collection in the figures below.

Description of the HEAD Cohort

Progression of the HEAD study cohort

Summary of Participant Enrollment and Measure Collection