Nose..

 

A recent study has revealed a tenuous but plausible link between picking your nose and increasing the risk of developing dementia.

In cases where picking at your nose damages internal tissues, critical species of bacteria have a clearer path to the brain, which responds to their presence in ways that resemble signs of Alzheimer's disease.

 It was demonstrated that in mice, the bacteria could travel up the olfactory nerve (joining the nasal cavity and the brain). What's more, when there was damage to the nasal epithelium (the thin tissue along the roof of the nasal cavity), nerve infections got worse.

This led to the mouse brains depositing more of the amyloid-beta protein – a protein which is released in response to infections. Plaques (or clumps) of this protein are also found in significant concentrations in people with Alzheimer's disease.