BDNF and Cognitive impairment: However, one recent study showed that prolonged exposure of postnatal day 7 (P7) rat pups to ketamine (20 mg/kg per dose) decreased BDNF expression and the phosphorylation of AKT and ERK and increased apoptosis in the developing rat hippocampus, which corresponded with later cognitive impairments (Meng et al., 2020).