PSEN1 and Alzheimer disease: To determine whether EVs isolated from biological fluids of AD patients and animal models exhibited Aβ-related neurotoxic properties similar to EVs released from cultured cells expressing mutant PS1, we measured the concentrations of Aβ42 and Aβ40 in EVs isolated from plasma samples from six transgenic APP/PS1 double-mutant transgenic mice,42 five 3xTgAD mice43 and nine age-matched wild-type mice.