While Alzheimer's is closely associated with abnormal clumps and tangles of proteins damaging neurons inside the brain, their findings suggest the initial trigger for the disease could be an outside intruder slipping through a compromised brain boundary.

As well as helping to prevent the disease, researchers say their findings could support healthy brain aging in general.

Lithium levels in human and mouse brains influence Alzheimer’s disease effects, but targeted replacement therapy may hold the key to intervention.