has a clear association with cerebrovascular changes.
Neurocognitive disorder due to another medical condition (e.g., neurodegenerative
disorders). When a diagnosis of major or mild NC D due to Parkinson’s disease is being
considered, the distinction must also be made from other brain diso rders, such as progres-
sive supranuclear palsy, corticobasal degeneration, multiple system atrophy, tumors, and
hydrocephalus. 
Neuroleptic-induced parkinsonism. Neuroleptic-induced parkinsonism can occur in
individuals with other NCDs, particularly when dopamine-blocking drugs are prescribed
for the behavioral manifest ations of such disorders
Other medical conditions. Delirium and NCDs due to side effects of dopamine-blocking
drugs and other medical conditio ns (e.g., sedation or impair ed cognition, severe hypothy-
roidism, B12 deficiency) must al so be ruled out. 
Comorbidity 
Parkinson’s disease may coexist with Alzheimer’ s disease and cerebrovascular disease, espe-
cially in older individuals. The compounding of  multiple pathological features may diminish
the functional abilities of individuals with Pa rkinson’s disease. Moto r symptoms and frequent
co-occurrence of depression or apathy can make functional impairment worse.
Major or Mild Neurocognitive Disorder
 Due to Huntington’s Disease
Diagnostic Criteria  
A. The criteria are met for major or mild neurocognitive disorder.
B. There is insidious onset and gradual progression.
C. There is clinically established Huntington’ s disease, or risk for Huntington’s disease
based on family history or genetic testing.