Description of the HEAD Cohort

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The HEAD study aims to enroll 620 individuals, including young healthy controls, individuals who are cognitively unimpaired, individuals with mild cognitive impairment, and individuals with AD dementia.

Data collection in the HEAD study is currently ongoing at all performance sites. The HEAD study includes a baseline visit and an 18-month follow-up visit, at which 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. Further assessments include the Mini-Mental State Examination (MMSE) as well as measures of socioeconomic status and female reproductive health.

• 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), NAV4694 (40-70 min), Neuraceq, or 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).