conditions. Among older adults, onset of neur ocognitive decline rela ted to cerebrovascular
disease or neurodegeneration (e.g., major or mild NCD due to Alzheimer’s disease) may
need to be differentiated. In general, stable, fluctuating (without progression) or improving
neurocognitive status would favor an HIV et iology, whereas steady or stepwise deter-
ioration would suggest neurodeg enerative or vascular etiolo gy. Because more severe im-
munodeficiency can result in opportunistic in fections of the brain (e.g., toxoplasmosis;
cryptococcosis) and neoplasia (e.g., CNS lymphoma), sudden onset of an NCD or sudden
worsening of that disorder demands acti ve investigation of non-HIV etiologies.
Comorbidity
HIV disease is accompanied by chronic systemic  and neuro-inflammation that can be as-
sociated with cerebrovascular disease and metabolic syndrome. These complications can
be part of the pathogenesis of major or mild NCD due to HIV infectio n. HIV frequently co-
occurs with conditions such as substance use disorders when the substance has been in-
jected and other sexually  transmitted disorders. 
Major or Mild Neurocognitive Disorder
 Due to Prion Disease
Diagnostic Criteria  
A. The criteria are met for major or mild neurocognitive disorder.
B. There is insidious onset, and rapid progression of impairment is common.
C. There are motor features of prion disease, such as myoclonus or ataxia, or biomarker
evidence.