IL1B and Cognitive impairment: Consistently, Clive Holmes, Barrientos et al. (18) and Bartynski et al. (19) found that basal IL-1β protein levels in the hippocampus did not differ between younger and older rats and that 4 days of lipopolysaccharide (LPS) administration produced substantial elevations in hippocampal IL-1β and caused cognitive impairment in the aged rats but not in adult rats.