CJD is a degenerative brain disease, meaning it causes damage to your brain that worsens over time. Experts classify it as a “transmissible spongiform encephalopathy” (TSE). The incubation period, which is the time it takes from when you first get the disease to when it starts causing symptoms, can range from months to years.
TSE conditions cause small pockets, or clusters, of damage throughout your brain. This damage causes your brain to look like a sea sponge or to have many holes or hollows like Swiss cheese.
As this brain damage happens, you lose the abilities controlled in the affected area. Overall, people with CJD develop a wide range of symptoms, including memory loss, problems thinking, uncontrolled muscle spasms or movement difficulties, and more. CJD is ultimately fatal because of how much damage it causes.