MAPT and Alzheimer disease: Furthermore, crossing Tat transgenic mice with APP-PS1 transgenic mice resulted in an increase in amyloid-β deposition, neurodegeneration, neuronal apoptotic signaling, and phosphorylated Tau compared with PSAPP mice79, indicating that Tat likely contributes to AD-like pathology in HIV. As the HIV-positive population ages, individuals with both HIV and canonical AD pathology are beginning to be diagnosed.