Main cognitive impairment is that of inattention (vs memory in dementia)
Generally develops over hours to days
Symptoms are classically described as fluctuating throughout the day (ie may appear normal in between episodes)
Acute onset of mental status changes and/or fluctuating course
Inattention
Disorganized thinking
Altered level of consciousness
A patient must possess both features 1 and 2 AND either 3 or 4 to meet<unk>  criteria
Delirium
Hypoxic encephalopathy
Excited delirium
Acute toxic-metabolic encephalopathy 
Acute psychosis
Hypoglycemia
Depression
Hyperosmolar state 