METTL3 and Alzheimer disease: METTL3 expression was significantly downregulated in the middle temporal gyrus associated with early cognitive impairment in AD patients, suggesting a key role of METTL3 in early AD [61], while METTL3 knockdown in hippocampal pyramidal neurons increased oxidative stress and abnormal cell cycle events, leading to significant reductions in the number of NeuN+ neurons and synapses, the activation of caspase-9/3, and increased apoptosis, causing cognitive deficits [61].