Study Suggests That Alzheimer’s Disease is Transmissible in Rare Circumstances

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A study published in Nature Medicine suggests that in rare circumstances, Alzheimer’s Disease can be transmissible. This goes against the current understanding of the disease, which is considered either a genetic or spontaneously occurring condition.

The new evidence suggests, however, that certain patients developed medically acquired Alzheimer’s disease. This occurred decades after the patients had been treated with a since discontinued human growth hormone (HGH) treatment. According to researchers, the HGH may have been tainted and allowed the patients to be exposed to amyloid beta protein (AB).

Alzheimer’s Disease symptoms, such as dementia, are a result of AB deposits in the brain.

The study is titled “Iatrogenic Alzheimer’s Disease in Recipients of Cadaveric Pituitary-Derived Growth Hormone.” It explains that between the years 1959 to 1985, about 1,848 patients were cadaveric pituitary derived HGH. It is believed that several batches of this medicine were tainted with AB. Researchers studied still living patients during routine medical visits and also conducted post mortem research on patients who had received the treatment and had since passed away.

Researchers were able to use similarly tainted HGH samples to transmit AB to mice in laboratory settings.

The study does not suggest that Alzheimer’s Disease is contagious, but it does suggest that exposure to certain substances can cause a patient to develop it due to iatrogenic reasons. In these circumstances, the evidence shows that there would be a significant period of latency between exposure and the development of symptoms. The evidence also suggests that it would take multiple instances of exposure for there to be a risk.

The patients researched for the study tended to develop symptoms at a younger age than typical for the disease. According to the report, four of the patients had developed symptoms between the ages of 38- to 49-years-old.

There is no evidence that Alzheimer’s can be transmitted during typical, daily life activities.

The study does not raise any concerns, as the treatments linked to the development of Alzheimer’s were long ago discontinued (due to the development of brain conditions in patients). However, it does provide researchers with a new understanding of the condition. Specifically, it shows that proteins linked to Alzheimer’s can behave like prions.

“This should further emphasize that the principles of prion biology have relevance for other neurodegenerative diseases involving the accumulation of diverse assemblies of misfolded host proteins, which may have propagating and neurotoxic forms,” researchers wrote in the study. “Our cases suggest that, similarly to what is observed in human prion diseases, iatrogenic forms of Alzheimer’s disease differ phenotypically from sporadic and inherited forms, with some individuals remaining asymptomatic despite exposure to AB seeds due to protective factors that, at present, are unknown.”

The study goes on to say that the results should lead to certain health considerations. For example, it notes the importance of effectively decontaminating surgical equipment for these proteins. It also notes the importance of care when treating disease related AB deposits.

Source

Banerjee, G., Farmer, S.F., Hyare, H. et al. Iatrogenic Alzheimer’s disease in recipients of cadaveric pituitary-derived growth hormone. Nat Med (2024). Accessed Jan. 30, 2024. https://doi.org/10.1038/s41591-023-02729-2