Australian researchers have shown that bacteria can travel through the olfactory nerve in the nose and into the brain of mice, where it creates markers that are a telltale sign of Alzheimer’s disease.

“We’re the first to show that Chlamydia pneumoniae can go directly up the nose and into the brain where it can set off pathologies that look like Alzheimer’s disease,” said James St John, who heads the Clem Jones Centre for Neurobiology and Stem Cell Research at Griffith University.