ITHACA, N.Y. -- Scientists have spent the last century studying a defense system in our bodies called the blood brain barrier.

Special cells safeguard the brain allowing only vital elements in or out through blood vessels. 

However, some experts say that same safeguard could also be keeping out medicines that could fight Alzheimer s and some Brain Cancers. 

Cornell University Microbiologist Dr. Margaret Bynoe has been studying FDA approved Lexiscan.

She says it essentially takes down the blood brain barrier defenses, allowing the drugs needed to treat diseases into the brain. 

"We found that the blood brain barrier returns to normal like within an hour after it has been permeabalized, it has been open," said Dr. Margaret Bynoe, Assoc. Professor Microbiolgy Cornell University. "So that adds a measure of safety for the patient. 

The research must still be presented to pharmaceutical companies with the hope of launching clinical trials in human patients with brain conditions.