The Pathology, Alzheimer’s and Related Dementias Study (PARDoS): Design and Characteristics of the First 4700+ Brazilian Participants

Abstract The Pathology, Alzheimer’s and Related Dementias Study (PARDoS) is a community-based clinical-pathologic study of aging and dementia in a large and diverse sample of Brazilians. Its long-term objective is to identify the environmental, genetic and molecular drivers of common conditions across the adult life span with an emphasis on Alzheimer’s Disease and Related Disorders clinical and neuropathologic traits. From July 31st 2021 through February 11th, 2025, more than 4,700 brains were collected at two autopsy centers and a major hospital system in the State of Sao Paulo, Brazil. Samples of other organs are also being collected. Their mean age was 71.7 years (range 18-106), 40.2% were Black/Mixed, 52.7% were male, their mean education was 6.3 years (range 0-25). Among those aged 65+, 32.9% had dementia and 18.8% had mild cognitive impairment. Neuropathologic data collection is ongoing. PARDoS fills several major gaps among clinical-pathologic studies given the large numbers and its unique age and education range, and socioeconomic status, race, sex, and other organ collection. Here we present the study design, demographic characteristics of the first 4,790 autopsied participants, and clinical characteristics of the first 4,283 with informant interviews. Competing Interest Statement The authors have declared no competing interest. Funding Statement PARDoS is supported by NIA grants R01AG54058 and R01AG075927. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Comissão Nacional de Ética em Pesquisa (CONEP), the Brazilian national ethics committee gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes