Nose-picking is a habit that is generally seen as unpleasant, but harmless.

The authors suggest that nose-picking damages the nasal mucosa, making it easier for the bacteria to reach the olfactory nerve and enter the brain.

A study from Australia has found that one bacterium, Chlamydia pneumoniae, enters the brain via the olfactory nerve from the nose leading to the development of amyloid beta plaques which are characteristic of Alzheimer’s.

Alzheimer’s disease is the most common form of dementia, and it is thought that both environment and genetics play a part in its development.

The olfactory nerve leads directly from the nasal cavity to the brain. Bacteria that enter the olfactory nerve can, therefore, bypass the blood-brain barrier that usually stops them from reaching the brain.

The habit of nose-picking may have some other health risks, including:  1. Introducing viruses, bacteria, and other contaminants into the nose 2. Spreading bacteria and viruses from the nose onto surfaces in the environment 3. Damaging the tissues and structures inside the nose