 PKR knockout mice or inhibition of PKR in mice enhances memory and learning.First report in 2002 has been shown that immunohistochemical marker for phosphorylated PKR and eIF2α was displayed positively in degenerating neurons in the hippocampus and the frontal cortex of patients with Alzheimer's disease (AD), suggesting the link between PKR and AD.Additionally, many of these neurons were also immunostained with an antibody for phosphorylated Tau protein.