https://www.scientificamerican.com/article/could-medical-procedures-transmit-alzheimers/

The seeds of Alzheimer’s disease may have been transmitted along with human growth hormone into eight British patients treated decades ago, according to a study published Thursday in Nature. If supported by further research, the findings imply Alzheimer’s could potentially be transmitted via close contact with the brain tissue of someone who has the disease.

That does not mean Alzheimer’s is contagious, researchers are quick to note. These eight patients all received doses of human growth hormone from the pituitary glands of numerous cadavers—a very unusual transmission route.