...Great links xT........Any
infection in the elderly can cause altered mental status. They are considered immunocompromised.. so they may not spike high fever or have a significant increase in the wbc. Thats why even 2 degrees higher is significant on elderly pts. Left shift granulocytes can be helpful in identifying infection.
Often infections are something you want to rule out when elderly presents with AMS. UTI being the common one for elderly, its checked by running a urinalysis and subsquent urine culture. The ability to respond to irregularities is weakend in the elderly and that makes small changes difficult with the system to deal with the stress...the proverbial straw that breaks the camels back.
As for pathophysiology, few things to think about
1) weakened immune system (to begin with) is put to the test with the infection which adds stress to the body.
2) Having fever.. results in diaphoresis.. could result in dehydration. they're usually dehydrated to begin with.
3) Metabolic changes
4) decreased O2 delivery to the brain during infection