Sporadic

Form: Sporadic CJD (sCJD)
Cause: Unknown
Distinguishing Features: Affects mainly people over the age of 60. Common symptoms include ataxia and dementia. Short course. Upon tissue examination there is spongiform change, but plaques are rarely present.

Form: Sporadic Fatal Insomnia (sFI)
Cause: Unknown
Distinguishing Features: Has clinical and histopathologic features indistinguishable from those of FFI, but does not have the mutation on the prion gene that characterizes FFI.