Mrs Robinson is an 88-year-old aged-care resident who has been hospitalised for pneumonia. On admission she is pleasant, alert, and orientated to person, place and time. The next day Mrs Robinson awakens when her name is called but then closes her eyes during the conversation. She is distracted by voices in the hallway, and questions must be repeated. She is now slurring her words and having difficulty with word finding. Which condition best explains Mrs Robinson's symptoms?
1) Delirium
2) Alzheimer's disease
3) Depression
4) Dementia