Can neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease be transmitted via blood transfusion? Researchers aimed to investigate this possibility in a new retrospective cohort study published in Annals of Internal Medicine

Some neurodegenerative disorders involve the aggregation of misfolded proteins in the brain. Researchers attempted to study possible transfusion transmission of neurodegenerative disorders using data from nationwide registers of transfusions in Sweden and Denmark. They analyzed 1,465,845 patients who received transfusions between 1968–2012. Hazard ratios for dementia of any type, Alzheimer’s disease, and Parkinson’s disease were estimated in patients receiving blood transfusions from donors who were later diagnosed with any of these diseases vs. patients who received transfusions from healthy donors. Study authors also evaluated whether excess occurrence of neurodegenerative disease occurred among those who received blood from a subset of donors. Transmission of chronic hepatitis prior to and after implementation of hepatitis C virus screening was also investigated. 

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Of the include patients, 2.95% received a transfusion from a donor diagnosed with one of the evaluated neurodegenerative diseases. The study found no evidence of transmission of any of the studied diseases regardless of approach. The hazard ratio for dementia in recipients of blood from donors with dementia vs. healthy donors was 1.04 (95% CI: 0.99–1.09). The estimates for Alzheimer’s disease and Parkinson’s disease were 0.99 (95% CI: 0.85–1.15) and 0.94 (95% CI: 0.78–1.14), respectively. Also, hepatitis transmissions was identified prior to but not after implementation of the screening. 

Overall, the study data did not demonstrate transmission of neurodegenerative diseases, and suggested that it would be rare if it does occur. Limitations to the study included an observational study design, underascertainment of the outcome, and possible insufficient statistical power. 

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