CJD is caused by an infectious protein known as a prion. One theory suggests that Alzheimer's disease may also be triggered by proteins that have gone rogue.

The presence of plaque in patients aged 36 to 51 is rare, and scientists involved in the study suspect that seeds of the amyloid protein may have transferred to the patients from the hGH injections they received, according to Nature.

If the results prove to be true after further study, it could have major implications in the surgical room. Specialized surgical tools and equipment might be required to undergo expensive decontamination procedures.

But skeptics warn that the study's sample size of just eight subjects is too small to draw any solid conclusions. Health experts encourage everyone to continue undergoing any medical procedures they've been advised to have.

Alzheimer's disease and related dementias affect approximately 47 million people worldwide, according to the Alzheimer's Association.

Alzheimer's most often begins in people over 65, although about 5 percent of cases are early-onset Alzheimer's.

For more information, read the study FAQ published by The Washington Post.