Faulty proteins in your brain known as prions cause CJD. Proteins are chemical molecules that need to hold a specific shape to work (like how a lock opens for a key with the right shape).
Your cells can’t use proteins when they aren’t the right shape, and your body can’t break them down. With nowhere to go, those proteins slowly build up in your brain cells (neurons), ultimately damaging and destroying the neurons. When your body makes faulty proteins for any reason, those misshapen proteins can cause degenerative brain diseases, like Alzheimer’s disease.
But prion-based diseases have a key difference. Instead of a slow build-up of faulty proteins, prions convert normal proteins into more prions. As the number of prions grows, they turn more proteins into prions. The more prions there are, the faster the conversion happens. That’s why CJD goes from mild behavior changes to severe symptoms so quickly.
Prions are also dangerous because they’re more resilient than most microbes. Cooking temperatures don’t destroy prions like viruses or bacteria. Your immune system can’t stop prions, so there’s no way to develop an immunity to CJD or a vaccine to prevent it.
Proteins can turn to prions in your body for multiple reasons. The different reasons are what determine the type of CJD you have. The different types are:
There are two specific genetic forms of CJD: