Novel techniques, including optogenetic activation of amyloidogenic pathways, viral vector-mediated delivery of mutated human genes (e.g., APP, MAPT), and synthetic tau fibril analogs, induce AD-like pathology, including amyloid-beta plaques, tau hyperphosphorylation, neuroinflammation, and synaptic loss in diverse species, ranging from transgenic rodents to cephalopods and cannies. The gene discussed is APP; the disease is Alzheimer disease.