CDKN1A and memory impairment: Chen and colleagues intraperitoneally injected d-galactose into mice to mimic age-related cognitive impairment and simultaneously administered HBOT, which significantly reversed d-galactose-induced learning and memory impairment and decreased p16Ink4a, p21Cip1/Waf1, and p53 expression in the hippocampus (Chen et al., 2016).