Tiny gas bubbles, embedded in a layer of fat molecules, can turn out to be the answer to a difficulty researchers have been struggling with for decades — the delivery of drugs to the brain. The method uses ultrasound to force the drug-containing bubbles over the barrier that prevents most substances from entering the brain. Although human trials using this approach are not yet in sight, the method offers a way of manipulating drugs so that they're likely to reach the brain of patients with Alzheimer’s disease and other brain conditions. Such treatments would have the benefit of increased efficacy with a lower risk of side effects. The study, "Lipid microbubbles as a vehicle for targeted drug delivery using focused ultrasound-induced blood-brain barrier opening," was published in the Journal of Cerebral Blood Flow and Metabolism. Using ultrasound to open up the impenetrable lining of blood cells in the brain — called the blood-brain barrier — has been experimented with for years. The sound waves are known to temporarily loosen the cellular connections making up the barrier, so as to let drugs inside, but that knowledge didn't make them an adequate drug delivery method. When a drug that is intended for the brain circulates in the blood, it has the potential to enter other tissues — causing unwanted side effects. Researchers at Columbia University in New York seem to have bypassed the problem. They designed tiny gas bubbles with the outer layer composed of fat molecules. When the drug is inserted into the fat layer, it stays in the bubbles as they circulated in the blood.