Major or Mild Neurocognitive Disorder Due to Prion Disease 635
D. The neurocognitive disorder is not attribut able to another medical condition and is not
better explained by another mental disorder.
Coding note:  For major neurocognitive disorder due to prion disease, with behavioral dis-
turbance, code first 046.79 (A81.9)  prion disease, followed by 294.11 (F02.81)  major
neurocognitive disorder due to prion disease,  with behavioral disturbance. For major neu-
rocognitive disorder due to prion disease, without behavioral disturbance, code first
046.79 (A81.9)  prion disease, followed by 294.10 (F02.80)  major neurocognitive disorder
due to prion disease, without behavioral disturbance.
For mild neurocognitive disorder due to prion disease, code 331.83 (G31.84).  (Note:  Do
not use the additional code for prion disease. Behavioral disturbance cannot be coded but
should still be indicated in writing.)
Diagnostic Features
The classification of major or mild neurocogni tive disorder (NCD) due to prion disease in-
cludes NCDs due to a group of subacute sp ongiform encephalopathies (including Creutz-
feldt-Jakob disease, variant Creutzfeldt-Jakob disease, kuru, Gerstmann-Sträussler-
Scheinker syndrome, and fatal insomnia) ca used by transmissible agents known as prions.
The most common type is sporadic Creutzfeld t-Jakob disease, typically referred to as
Creutzfeldt-Jakob disease (CJD). Variant CJD is  much rarer and is associated with trans-