CJD does not cause any symptoms at first. The first symptoms include slow thinking, difficulty concentrating, impaired judgment and memory loss. These symptoms also occur with other diseases, such as Alzheimer's disease, so CJD can be hard to diagnose, at first.
Soon, however, begins a severe, progressive dementia. People neglect themselves, become apathetic or irritable, and start having strong muscle spasms. Then people become completely bedridden, and eventually lapse into coma. Comatose patients may die as a result of infection associated with being immobile, such as pneumonia.