Inflammatory cytokines like IL-6, IL-1, and tumor necrosis factor can signal the brain and lead to cognitive impairment and poor memory during severe illness.

“As you have an an infection for many hours or days, the amount of IL-6 and IL-1 and tumor necrosis factor, and other inflammatory cytokines is starting to increase such that the total amount in your circulation gets high enough and is communicated to the brain. And it tends to enter the brain through a particular type of tissue that's really interesting called choroid, C-H-O-R-O-I-D. The choroid starts releasing and responding to these cytokines, the inflammatory cytokines, and then the brain actually starts to experience all sorts of changes in terms of inflammation to neurons, to memory tends to get poor, your cognition tends to get poor.”