The Parkinson’s Progression Marker Initiative (PPMI) is an observational, international study designed to establish biomarker defined cohorts and identify clinical, imaging, genetic and biospecimen Parkinson’s disease (PD) progression markers to accelerate disease modifying therapeutic trials. A total of 423 untreated PD, 196 Healthy Control (HC), 64 SWEDD (scans without evidence of dopaminergic deficit) subjects, and 65 Prodromal subjects (individuals with hyposmia or REM Sleep Behavior Disorder) were enrolled. PPMI is actively enrolling affected and unaffected individuals with genetic mutations in LRRK2, GBA, or SNCA through the end of 2018. For the most up to date enrollment numbers, please visit To enroll PD subjects as early as possible following diagnosis, subjects were eligible with only asymmetric bradykinesia or tremor plus a dopamine transporter (DAT) binding deficit on SPECT imaging. Acquisition of data was standardized as detailed at

The LRRK2 Cohort Consortium (LCC) comprises three closed studies: the LRRK2 Cross-sectional Study, LRRK2 Longitudinal Study and the 23andMe Blood Collection Study. The LCC followed standardized data acquisition protocols, and clinical data and biological samples are stored in a comprehensive Parkinson’s database and biorepository, respectively. A total of 1,213 Idiopathic PD subjects, 1,168 PD subjects with genetic mutations in LRRK2, 1,123 unaffected subjects with genetic mutations in LRRK2, and 779 Healthy Controls (HC) were recruited.

The Mayo Clinic Study of Aging was designed to establish a prospective population-based cohort of subjects to study prevalence, incidence and risk factors for MCI and dementia. The study was conducted in Olmsted County, where several factors enhance the feasibility of population-based epidemiologic research. Most residents seek care within the community from essentially 2 providers, the Mayo Clinic and Olmsted Medical Center, along with their affiliated hospitals and medical facilities within the county. Both healthcare providers use a unit medical record which includes all outpatient and inpatient information for each patient. The study began October 1, 2004, and recruitment is ongoing to maintain a sample size of about 3,000 active participants. Participants are randomly selected from the Olmsted County population using a sex and age-stratified sampling scheme. Selected participants are invited to participate; exclusion criteria are persons who are in hospice or terminally ill or demented, but recruitment of persons with dementia began in 2015. Nearly 6,000 participants have been recruited to date. At the onset of the study, only 70-89 year olds were eligible. Recruitment of 50-69 year-olds began in 2012, and recruitment of 30-49 year olds began in 2014. Followup is performed every 15 months for 50 yrs and older; every 30 months if younger than 50 years by face-to-face visits in the Center, in-home, or by phone for a minority who decline either of the two but still would like to participate. Medical records are reviewed is used to identify prevalent and incident medical conditions (e.g. vascular diseases such as diabetes, hypertension) and incident dementia cases among persons lost to follow-up.

The Open Access Series of Imaging Studies (OASIS) is a project aimed at making MRI data sets of the brain freely available to the scientific community.

OASIS: Cross-sectional MRI Data in Young, Middle Aged, Nondemented and Demented Older Adults
This set consists of a cross-sectional collection of 416 subjects aged 18 to 96. For each subject, 3 or 4 individual T1-weighted MRI scans obtained in single scan sessions are included. The subjects are all right-handed and include both men and women. 100 of the included subjects over the age of 60 have been clinically diagnosed with very mild to moderate Alzheimer’s disease (AD). Additionally, a reliability data set is included containing 20 nondemented subjects imaged on a subsequent visit within 90 days of their initial session.

OASIS: Longitudinal MRI Data in Nondemented and Demented Older Adults
This set consists of a longitudinal collection of 150 subjects aged 60 to 96. Each subject was scanned on two or more visits, separated by at least one year for a total of 373 imaging sessions. For each subject, 3 or 4 individual T1-weighted MRI scans obtained in single scan sessions are included. The subjects are all right-handed and include both men and women. 72 of the subjects were characterized as nondemented throughout the study. 64 of the included subjects were characterized as demented at the time of their initial visits and remained so for subsequent scans, including 51 individuals with mild to moderate Alzheimer’s disease. Another 14 subjects were characterized as nondemented at the time of their initial visit and were subsequently characterized as demented at a later visit.

Last Update 21/09/2017

The Wisconsin Longitudinal Study (WLS) is a longitudinal population cohort started in 1957, with a questionnaire administered to all Wisconsin High School seniors. In 1964, a randomly selected one-third of the members of the class of 1957 were followed up with a brief questionnaire to parents asking about their child’s post high-school education and occupation. Direct contact with the graduate began with a telephone interview in 1975, and subsequent telephone and mail surveys in 1993 2004. In 1977 a subset of graduate’s siblings were interviewed by phone and in 1995 and 2005 interviews were conducted with one sibling from each family whenever possible. Spouses of Graduates and Siblings who were married at the time of the 2004/2005 interview were also interviewed by phone. Most recently in-person interviews with a leave-behind questionnaire were administered in 2011 to both the graduate and sibling panels. Saliva was collected from both graduate and sibling participants via a mail-effort in 2008 and during the in-person 2011 interview.

Last Update 21/09/2017 

STROKOG is a consortium of longitudinal studies of cognitive disorders following stroke, TIA or small vessel disease. Developed under the auspices of VASCOG (Society for the Study of Vascular Cognitive and Behavioural Disorders), it is the first international effort to harmonise work on post-stroke dementia and is being led by CHeBA researchers.

The consortium brings together studies that have examined post-stroke or other high vascular risk cohorts longitudinally, with cognitive decline and dementia (including sub-types) as primary outcome variables. The included studies (N=27; total sample of more than 10,000 individuals, representing 17 countries) have rich neuropsychological and MRI data, and some recent studies (n=3) have included amyloid imaging in sub-samples. A number of studies have CSF and/or plasma available for biomarker studies, and participant enrolment in brain banks for neuropathology.

Last Update 21/09/2017

The Puerto Rican Elderly: Health Conditions (PREHCO) study investigates issues affecting the elderly (individuals over 60 years of age) population in Puerto Rico: health status, housing arrangements, functional status, transfers, labor history, migration, income, childhood characteristics, health insurance, use of health services, marital history, mistreat, sexuality, etc. It is an island-wide, longitudinal sample survey of target individuals and their spouses with two waves of data collection: 2002-2003 and 2006-2007.

In the first phase of the PREHCO project, 4,291 elderly persons 60 years or older and 1,442 spouses were interviewed (1,042 of the latter being 60 years or older). A second wave of the project (2006-2007) converted PREHCO in a longitudinal study. In the second wave, those same participants were asked to do a follow-up survey, in which 3,891 target interviews and 1,260 spouse interviews were completed. The deceased and institutionalized participants were also interviewed using a proxy.

Last Update 21/09/2017

The first wave of the MIDUS study collected survey data from a total of 7,108 participants. The baseline sample was comprised of individuals from four subsamples:

  1. a national RDD (random digit dialing) sample (n=3,487);
  2. oversamples from five metropolitan areas in the U.S. (n=757)
  3. siblings of individuals from the RDD sample (n=950); and (4) a national RDD sample of twin pairs (n=1,914).

All eligible participants were non-institutionalized, English-speaking adults in the coterminous United States, aged 25 to 74. Data from the above samples were collected primarily in 1995/96.

Last update – 03/02/2017

ADNI began in October 2004. The overall goal is to validate biomarkers for Alzheimer’s disease clinical trials. One aim is to find, validate and standardize more sensitive and accurate methods to detect Alzheimer’s disease at earlier stages and mark its progress through biomarkers. The study gathered and analyzed thousands of brain scans, genetic profiles, and biomarkers in blood and cerebrospinal fluid that are used to measure the progress of disease or the effects of treatment. More information on All data is publically available at USC/LONI/ADNI.

The three overarching longitudinal ADNI study goals are:

  • Validation of biomarkers, especially for amyloid and tau, for use in AD clinical trials.
  • To detect Alzheimer’s disease (AD) at the earliest stage possible and identify ways to track the disease through biomarkers.
  • To support advances in AD intervention, prevention and treatment through the application of new diagnostic methods to apply at the earliest stages technically possible – when intervention may be most effective.
  • To continually develop ADNI’s now- legendary data access policy and continuously improve and expand the unprecedented data sharing model.

Last update – 07/02/2017

The University of Michigan Health and Retirement Study (HRS) is a longitudinal panel study that surveys a representative sample of approximately 20,000 people in the United States.

Last update: 21/01/2017