differential diagnosis. Some subtypes (e.g., those related to traumatic brain injury or
stroke) typically begin at a specific time and (at least after initial symptoms related to in-
flammation or swelling subside) remain stat ic. Others may fluctuate over time (although
if this occurs, the possibility  of delirium superimposed on  NCD should be considered).
NCDs due to neurodegenerative diseases like Alzheimer’s disease or frontotemporal
lobar degeneration typically are marked by insidious onset and gradual progression, and