In the past week, you may have seen a few news headlines that talked about the idea that Alzheimer’s disease may be contagious. I’ve seen headlines like “Alzheimer’s Disease Contagious Like Mad Cow,” “Some Cases of Alzheimer’s May Be Transmitted,” and “Can You ‘Catch’ Alzheimer’s Disease?” Those all sound pretty scary, like something out of a sci-fi movie about a looming global Alzheimer’s pandemic. But when you look at the finding that spawned these sensational headlines, you may be comforted to know that the research does not show anything quite so dire.
The study involved injecting human brain tissue into mice, a condition which researchers admitted was highly artificial. The summary version of the study is that researchers took proteins from the brain of humans with Alzheimer’s and put them into the brains of healthy mice. The mice then developed Alzheimer’s. The conclusion, that injecting diseased brain tissue into a healthy brain causes disease, led to this notion that the mice “caught” the disease from the human tissue. But how often do you inject tissue from one brain into another, outside of an experiment? And do I need to point out that this was a case of inter-species brain tissue injection, an even more unlikely scenario? If you decode what the paper actually reports, it’s even less scary. The paper, entitled De novo induction of amyloid-ß deposition in vivo, looks at just one associated (not causal) factor of AD, which is amyloid-β proteins.
The researchers who were interviewed mentioned that there was a resemblance to Mad Cow disease from the standpoint of how the proteins in the brain were affected, but they did not imply a similarity in how it was transmitted. Unfortunately some journalists have chosen to interpret this by making dramatic statements like “Imagine having to deal with an elderly loved one wearing a moon suit? Terrible.” In my opinion, this type of reporting is incredibly irresponsible. As with so many journalistic distillations of complex scientific findings, headlines like these don’t get at the real story, choosing instead to extrapolate from the actual finding to craft a more sensational story.
I do not wish to denigrate the significance of this preliminary finding, because I believe it could help us get closer to understanding the underlying mechanisms of AD. However, I am deeply troubled by the misrepresentation of the reporting in these articles. Could aspects of Alzheimer’s be infectious under certain but limited circumstances involving tissue transplantation? Maybe. Should you be scared to give grandma a hug because you’re going to “catch” AD from her? No. While these kinds of studies are crucial to our growing understanding of AD, representing them inaccurately with sensationalized headlines is fear-mongering at its worst.