Can You “Catch” Alzheimer’s?

A recent claim made major news around the world, stating that you can “catch” Alzheimer’s disease. Take a closer look at the claim, the study behind the claim and why that study did not prove Alzheimer’s can pass between people.Can You "Catch" Alzheimer's?

Examining the Claim: Can You “Catch” Alzheimer’s?

As the world becomes more aware of the growing Alzheimer’s epidemic and new studies become major news headlines, it is not surprising that every now and then study results become exaggerated.

That is exactly what happened last month when major headlines around the world claimed that: “You Can Catch Alzheimer’s.” Claims like this do more than spread fear. They can perpetuate stereotypes and increase the stigma that surrounds Alzheimer’s, creating an environment of isolation for people living with a  diagnosis that already leaves them feeling isolated.

Examining the study that led to this claim quickly debunks any merit behind the claim. A neurologist at the Mayo Clinic in Minnesota, David Knopman, MD, was appalled by the claims. When asked if people should be worried about catching Alzheimer’s he responded:

“No… and then I would repeat, ‘No.’ Again, ‘No.’” 

A Closer Look at the Study Behind the Claim

The study that launched this claim was actually a study on prion diseases. Prions cause a number of neurodegenerative conditions likes Creutzfeldt-Jakob disease (CJD), also known as mad cow disease, when present in cows. Prion diseases involve rapid memory loss, a loss of hand and eye coordination, behavioral changes and cause death. Prions can pass through blood and human tissue transplants and damage other proteins just by touch.

Before 1985, some shorter children were injected with a growth hormone taken from human tissue to help them grow taller. Unfortunately, some of this tissue was contaminated with prions and so some children who received the contaminated injections went on to develop CJD. In a new study, researchers conducted autopsies on eight people between the ages of 26-51 who had been treated with the contaminated growth hormone and had died from CJD.

In the autopsies, researchers noted that four of the eight people had a significant amount of beta-amyloid build up, like that commonly seen in the brains of people with Alzheimer’s. After ruling out any genetic disposition that would lead such young people to have such high amounts of beta amyloid in the brain and any link between CJD and amyloid build up, researchers concluded that the growth hormone shots must have also had beta amyloid in them that worked their way to the brain, acting like a prion, damaging other beta amyloid proteins and growing plagues.

This would mean that beta-amyloid could be passed from person to person, similar to prions

Lack of Evidence Calls for More Research

Researchers caution that there is a lot to learn about beta amyloid proteins and Alzheimer’s before claiming that the disease is contagious. Important things to note about this study include:

  1. The participants did not have Alzheimer’s disease. There was no presence of the tau protein in the brain and both tau and beta amyloid are involved in the development of Alzheimer’s. Knapman says, “You have to have both (beta amyloid and tau) to have Alzheimer’s disease, and they didn’t see that. None of these articles or press releases should say ‘Alzheimer’s”.
  2. The relationship between beta amyloid plagues and Alzheimer’s is still unknown. While people who have Alzheimer’s have beta amyloid plagues in their brains, researchers do not know if these plagues are a cause or a consequence of Alzheimer’s.
  3. There is no proof that the beta amyloid present in the brains of the four participants came from the growth hormone injections. As researcher, neurologist and head of the department of neurodegenerative disease at University College London John Collinge noted, “This is an observational study. We’re simply describing what we see in these patients and trying to explain that. It doesn’t prove that it was the growth hormone injections that caused their Alzheimer’s pathology.”

While this study certainly does not prove that Alzheimer’s is contagious, it does raise questions about the pathology of the disease that merit more research.

What do you think about claims that Alzheimer’s is contagious? How do irresponsible claims damage the progress made in the fight against Alzheimer’s?  Share your thoughts with us in the comments below.

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