Berkeley Aging Cohort Study (BACS) – Data sharing

Introduction: BACS data are available for sharing with the scientific community. If you visit the GAAIN (https://gaain.org) website, you can explore available data from our study and then return to this site for a data request. The data request requires completion of a data use agreement (DUA) that is available below. Please download the DUA, have it signed by your institutional official and upload it to this site. After review of the DUA we will directly share study numerical data as csv files or a data set of images, along with a data dictionary. The data dictionary is also available below for download.

The DUA will ask you to specify which data you would like, and the purpose of your research. Data are available as a csv file with all available numerical results for amyloid and tau PET, MRI, and demographic and cognitive/behavioral variables for all participants at all visits. If you would like images you will need to specify the nature of the image data set you require and this can include any combination of modality and timepoints.

Overview: BACS is an ongoing study that is comprised of individuals from the San Francisco Bay Area, largely from Berkeley and nearby communities. Individuals were recruited by flyers, advertisements, word of mouth and as such are not representative of any particular group – BACS is a convenience sample. All individuals are cognitively unimpaired and largely adults over the age of 65 although there is a small sample of young adults (age >20) who have participated as young controls over the years. The project began recruiting participants in 2005, and initial studies included cognitive testing, 1.5T structural MRI and [¹¹C]Pittsburgh compound B (PIB) PET. Over time, the neuropsychological battery has changed slightly and tau PET imaging and higher field MRI were added after the study began (details below). The main available measures are a standard battery of neuropsychological tests, PIB-PET, tau PET scans using [¹⁸F]Flortaucipir (FTP) and structural MRI. Basic demographic details, ApoE genotype, and a number of lifestyle and other questionnaires were also included in the evaluation. Participants are followed approximately every 2 years with repeat neuropsychological tests, PET scans and MRIs.

All dates in the database are provided as the number of days since the index date, which is the date of the first PIB-PET scan.

Available data includes:

• Basic demographics
• APOE genotype
• Numerical data for PIB-PET as SUVrs in Desikan-Killiany ROIs and a cortical summary ROI with SUVR and Centiloid values (used to define amyloid positive/negative or as a continuous variable).
• Numerical data for Flortaucipir PET as SUVrs in Desikan-Killiany ROIs
• Numerical data for MRI volumes and cortical thickness in Desikan-Killiany ROIs
• PET and MR images

The data dictionary lists labels for all numerical data and is available below.

Available Scans: PET data were collected on a Siemens Biograph 6 PET CT with the exception of PIB-PET data collected prior to 2012 that was collected on a Siemens ECAT HR. MR data were collected on a Siemens Avanto 1.5T scanner or Siemens 3T trio or Prisma scanner.

T1 MPRAGE MR images were converted to nu.mgz using FreeSurfer. This file was converted to nu.nii that was coregistered and resliced to the baseline MRI to create the rnu.nii file that is available for download.

PET images are available as 50-70 min after injection for PIB and 80-100 in after injection for FTP. DICOM or ECAT files were converted to NIFTI format that are then realigned, resliced and averaged. The averaged file is coregistered and resliced to the MRI (rnu.nii) nearest in time using SPM12. These images are intensity normalized to the cerebellar grey matter for PIB and inferior cerebellar grey matter for FTP. The images can also be normalized using other reference regions taken from the table of SUVRs if you prefer. The shared files have suvr_cereg.nii descriptors.

Numerical image data: Numerical PET SUVrs (50-70 min post injection for PIB and 80-100 min post injection for FTP) are obtained using the Berkeley PET Imaging Pipeline (BPIP). All images are processed with the MRI-dependent pipeline. Further information is available in this publication:

Landau SM, Harrison TM, Baker SL, Boswell MS, Lee J, Taggett J, Ward TJ, Chadwick T, Murphy A, DeCarli C, Schwarz CG, Vemuri P, Jack CR, Jr., Koeppe RA, Jagust WJ, Group USPS, for the Alzheimer's Disease Neuroimaging I. Positron emission tomography harmonization in the Alzheimer's Disease Neuroimaging Initiative: A scalable and rigorous approach to multisite amyloid and tau quantification. Alzheimers Dement 2025; 21:e14378.

https://alz-journals.onlinelibrary.wiley.com/doi/full/10.1002/alz.14378

In addition to regional SUVRs, the downloadable csv files contain summary ROIs as a global amyloid SUVR and centiloid value for PIB and a summary temporal meta-ROI for flortaucipir.

Cognitive data: BACS participants have cognitive assessments approximately every 2 years. The instruments used for cognitive testing are below. Abbreviations are listed as used in the data dictionary. The data dictionary provides a description of each variable but further information is provided in the reference articles describing the tests.

TEST	CITATION
Wisconsin Card Sorting Task (WCST)	Heaton, RK (1993). Wisconsin Card Sorting Test Manual. Psychological Assessment Resources, Inc.
Mini Mental State Examination (MMSE)	Folstein MF, Folstein SE, McHugh PR. (1975). "Mini- Mental State" A practical method for grading the cognitive state of patients for the clinician. J Psychiat Res, 12: 189- 198. Also patented and sold by Psychological Assessment Resources, Inc (www.minimental.com)
California Verbal Leraning Test, Second Ed. (CVLT-II)	Delis, D.C., Kramer, J.H., Kaplan, E., & Ober, B.A. (2000). California Verbal Learning Test: Second Edition. San Antonio, TX: Psychological Corporation.
Visual Reproduction	Wechsler, D. (1997) The Wechsler Memory Scale - Third Edition: Administration & Scoring Manual. San Antonio, TX: The Psychological Corporation.
Trail Making	Reitan, R. M., & Wolfson, D. (1985). The Halstead–Reitan Neuropsychological Test Battery: Therapy and clinical interpretation. Tucson, AZ: Neuropsychological Press.
Digit Span (ds)	Wechsler, D. (1997) The Wechsler Memory Scale - Third Edition. San Antonio, TX: The Psychological Corporation.
Stroop Task	Golden, 1978 C.J. Golden, Stroop Color and Word Test: A Manual for Clinical and Experimental Uses, Skoelting, Chicago, IL (1978), pp. 1–32.
Digit Symbol Task (Symbol-Digit)	Smith, A. (1982). Symbol Digit Modalities Test: Manual. Los Angeles: Western Psychological Services.
Boston Naming Task	Mack, W.J. et al. (1992). Boston Naming Test: shortened versions for use in Alzheimer's disease. , 47(3), 154-8.
Listening Span	Salthouse T, Babcock R (1991). Decomposing adult age differences in working memory. Dev Psychol 27:763-776. Discontinued 2019
Mental Control	Wechsler, D. (1997) The Wechsler Memory Scale - Third Edition. San Antonio, TX: The Psychological Corporation.
Verbal Paired Associates (vpa)	Wechsler, D. (1997) The Wechsler Memory Scale - Third Edition. San Antonio, TX: The Psychological Corporation.
Vocabulary	Wechsler, D. (1997) The Wechsler Adult Intelligence Scale - Third Edition: Administration & Scoring Manual. San Antonio, TX: The Psychological Corporation.
FAS/Controlled Word Association	Spreen, O., & Benton, A. L. (1977). Neurosensory Center Comprehensive Examination for Aphasia: Manual of instructions (NCCEA) (rev. ed.). Victoria, BC: University of Victoria..
Logical Memory (lm)	Wechsler, D. (1997) The Wechsler Memory Scale - Third Edition. San Antonio, TX: The Psychological Corporation.
Famous faces (nufface)	Gefen T, Wieneke C, Martersteck A et al. (2013) Naming vs knowing faces in primary progressive aphasia. Neurology 81:658-664. Discontinued 2023
Physical Activities Questionnaire	Siscovick DS, et al. (1997) Exercise Intensity and Subclinical Cardiovascular Disease in the Elderly, The Cardiovascular Health Study. Am J Epidemiol 145:977-86.
AMNART (American version of National Adult Reading Test)	Grober, E. & Sliwinski, M. (1991). Development and validation of a model for estimating premorbid verbal intelligence in the elderly. Journal of Clinical and Experimental Neuropsychology, 13, 933-949.

In-home questionnaires

"Big 5" Personality inventory (b5)	John, O. P., Naumann, L. P., & Soto, C. J. (2008). Paradigm Shift to the Integrative Big-Five Trait Taxonomy: History, Measurement, and Conceptual Issues. In O. P. John, R. W. Robins, & L. A. Pervin (Eds.), Handbook of personality: Theory and research (pp. 114-158). New York, NY: Guilford Press.
Cognitive Activity Interview (CAI)	Wilson, R. S., Bennett, D. A., Gilley, D. W., Beckett, L. A., Barnes, L. L., & Evans, D. A. (2000). Premorbid reading activity and patterns of cognitive decline in Alzheimer disease. Archives of Neurology, 57(12), 1718-1723. Discontinued 2019
Lifetime Experiences Questionnaire (LEQ)	Valenzuela MJ, Sachdev P (2007) Assessment of complex mental activity across the lifespan: development of the lifetime of experiences questionnaire. Psychological Medicine 1015-25
Geriatric Depression Scale (GDS)	Yesavage, JA, et al. (1983) Development and Validation of a Geriatric Depression Screening Scale: A Preliminary Report. J. psychiat. Res., Vol. 17, No. 1, 37-49
CES-D (replaces GDS for young participants)	Radloff, L. S. (1977). The CES-D scale: a self-report depression scale for research in the general population. Applied psychological measurement, 1(3), 385-401.
Pittsburgh Sleep Questionnaire (PSQI)	Buysse, D. J., Reynolds, C. F., Monk, T. H., Berman, S. R., & Kupfer, D. J. (1989). The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Research, 28(2), 193-213.

BACS methods are described in greater detail in a number of publications some of which are listed below:

Giorgio J, Adams JN, Maass A, Jagust WJ, Breakspear M. Amyloid induced hyperactivity in default mode network drives medial temporal hyperactivity and early tau accumulation. Neuron 112:676-686, 2024

Pezzoli, S, Giorgio J, Chen X, Ward TJ, Harrison TM, Jagust WJ. Cognitive aging outcomes are related to both tau pathology and maintenance of cingulate cortex structure. Alzheimers Dement 2025, https://doi.org/10.1002/alz.14515

Bhade M, Pezzoli S, Giorgio J, Ward TJ, Winer JR, Harrison TM, Landau SM, Jagust WJ. Modifiable risk factor profiles moderate the effect of beta-amyloid pathology on cognition in aging. Neurobiol Aging 2025; 152:54-63.

Ziontz J, Harrison TM, Fonseca C, Giorgio J, Han F, Lee J, Jagust WJ. Connectivity, pathology and ApoE4 interactions predict longitudinal tau spatial progression and memory. Human Brain Mapping Dec 1;45(17):e70083. doi: 10.1002/hbm.70083. PMC11626484

Filling out the Data Use Agreement: Please have the form reviewed and signed by an individual at your institution who has the authority to enter into contracts. Most of this form should be self explanatory. If you use this form without modification, it can most likely be approved in a week or so. Modifications will introduce the need for local review that could extend the time for approval significantly.

Exhibit A is crucial information that requires a description of the science. Please explain the hypotheses you intend to test and provide a broad, high-level description of the analyses you intend to run. Most importantly provide a list of the data elements that you require, specifically whether you want images themselves or just the numerical results of image analyses, cognitive data, and longitudinal data. Specifying the exact fields on the data dictionary would be most helpful.