8 upvotes, 0 direct replies (showing 0)
Often times the delirium presents **without** fever, actually, and this is kind of a well-known sign in elderly for being a red flag for infection.
As for why this happens, we don't really know, but one theory as to why is that the Blood-Brain Barrier in elderly patients has been somewhat eroded due to time; it's lost it's "rigidity" of sorts. Due to this, inflammatory cytokines can possibly pass through the BBB and cause trouble in the central nervous system.
Sometimes, the infection just jumps to the brain or CNS, and this is the cause of delirium.
And sometimes, infections cause metabolic disturbances (this would be the fever, dehydration, electrolyte imbalances, hypoxia, etc) and in elderly folks with fewer physiological reserves due to age, these can trigger way bigger responses than in young folk.
But like I said, many times delirium presents without fever in the elderly, in which case, it could be another form of metabolic disturbance (i.e, dehydration), CNS infection, or inflammatory cytokines attacking/fudging with the CNS.
There's nothing here!