Are some cases of Alzheimer’s disease caused by infection?

Some scientists believe that microbes might play a part in Alzheimer’s disease development. They say it could be that certain viruses or bacteria that infect the brain aren’t completely eradicated by the immune system, which leads to neuroinflammation and brain cell death. It could also be that microbes trigger the release of protein deposits—amyloid-beta plaques and tau tangles—which kill neurons, further increase neuroinflammation, and lead to more neuron death.