A new discovery allows doctors to inject drugs straight into people's brains, a breakthrough that overcomes a major obstacle to treating Alzheimer's, brain cancers, and other diseases that affect the central nervous system, such as multiple sclerosis and Parkinson's.

The blood-brain barrier (BBB) is protective, filtering out chemicals and microbes that might cause us harm. But it's also a major problem for treating diseases because it filters out drugs that are meant to heal. Very few molecules are allowed to cross the BBB.

A group of researchers from the Canadian National Research Council has developed special molecules that can penetrate the BBB by using the same mechanism that allows nutrients to enter the brain. Scientists hope the molecules can be used as a carrier to deliver special drugs called biologics (peptides, antibodies, and enzymes) straight to the brain and release them exactly where they are needed.

Animal trials have already shown the molecules have "highly potent" therapeutic effects on brain diseases, and the scientists are hoping to advance to human trials.