Pre- and postsynaptic GIRK1 and 2 subunit density in the CA1 hippocampus is also decreased in APP/PS1 mice at 12 months (Martin-Belmonte et al. 2022), potentially leading to dysfunction of signaling through GABABRs. Early human studies have also found reduced numbers of GABABRs in the hippocampus of individuals with AD (Chu et al. 1987). This evidence concerns the gene APP and Alzheimer disease.