A recent study found that not only the constitution Aβ and p-S396-tau in exosomes markedly differed between patients with AD compared to the controls, but the exosomes from patients with AD were smaller and lower in quantity, as determined by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA), contributing to the early diagnosis of AD (Sun et al., 2020). This evidence concerns the gene MAPT and Alzheimer disease.