MAPT and Alzheimer disease: At present, α-synuclein has been found to be correlated with a variety of neurodegenerative diseases, and has different expression in different diseases.[25] Garcia et al found a significant positive correlation between alpha-synuclein and tau in cerebrospinal fluid of AD patients, and both showed similar changes in AD episodes, which was also confirmed in animal experiments.[26] Consistent with the changes in tau, α-synuclein was significantly upregulated in cerebrospinal fluid of AD patients.[21] The neurotoxicity of α-synuclein mainly lies in the alteration of synaptic function.