The abnormal form differs in shape from the normal prions and is not susceptible to enzymes that normally break down proteins. In the brain, abnormal prions appear to increase their number by directly converting normal prions to the abnormal form. When the abnormal prion proteins attack the brain tissue, the neurological problems may begin. Patients affected by CJD are most often between the ages of 50 and 75. Affected individuals eventually lose the ability to speak and move, and enter a coma.
Diagnosis is based on symptoms, electroencephalograms, and neuropathological tests.
A neurologic test and spinal tap are usually performed on suspected cases to rule out other treatable causes of dementia such as encephalitis or meningitis. However, the only way to confirm a diagnosis of CJD is by brain biopsy or autopsy. Since a correct diagnosis of CJD does not help the patient, a brain biopsy is discouraged because of dangerous risks unless it is needed to rule out a treatable disorder. Researchers have tested many drugs, including amantadine, steroids, interferon, acyclovir, antiviral agents, and antibiotics. However, none of these treatments has shown any consistent benefit.