Reacción a "Reactions: five cases of Alzheimer's described that may have been transmitted by growth hormone treatments from cadavers"

This study looked at whether people can develop Alzheimer’s disease as a result of a growth hormone treatment that is no longer used. As the authors of this study mention, there is no suggestion that Alzheimer’s pathology can be transmitted between individuals in activities of daily life. There is also no evidence that would provoke worry about current surgical procedures carrying any risk of transmitting Alzheimer’s disease. This current paper is a description of 8 people who received several years of injection of growth hormone extracted from human cadavers during childhood, 5 of whom went on to develop dementia 30-40 years later.  The scientists attribute these symptoms to possible transmission of Alzheimer’s-related amyloid pathology from the growth hormone that started clumping of this amyloid in the brains of these people.  While this is possible based on this paper and their previous data, it is not something for people to worry about as that type of growth hormone treatment is no longer used and even in people treated with that growth hormone, this outcome is very rare.  Further, it is not possible to know for sure whether these people developed dementia due to their growth hormone treatment for several reasons: this study only looked at 8 people (a very small sample size), several of the people also had other risks for dementia like intellectual disability (in 2 cases) or a gene that substantially increase risk of Alzheimer’s (1 case), and the pathology shown in the paper for the people who donate post-mortem brain tissue is much milder than is found in people who died from Alzheimer’s disease.