See the entry for differential diagnosis of delirium (acute change in mental status). It’s more detailed and includes a differential that applies for this entry.
Vascular – stroke, TIA, subarachnoid hemorrhage
Infectious + inflammation– meningitis, encephalitis, sepsis
Neoplastic – primary brain tumor or metastasis
Drugs – narcotics, alcohol intoxication or withdrawal
Iatrogenic /idiopathic-
Congenital – AVM that is grown in size/ruptured.
Autoimmune – CNS lupus, etc.
Traumatic – traumatic brain injury, traumatic epidural or subdural hematoma
Endocrine/metabolic – hypoglycemia, Hyperglycemic hyperosmolar state, DKA, hypo- or hyperthyroidism, hypo- or hypernatremia, hypercalcemia, hepatic or uremic encephalopathy
Musculoskeletal and rheumatologic.
Environmental
Neuropsychiatric: Neurologic disorders – epilepsy (post-ictal state), Alzheimer’s disease, Huntington’s disease, other dementias. Psychiatric disorders: Psychosis, etc.