A Spanish study using monkeys has shed light on how sound waves can deliver drugs to the brain, for diseases such as Alzheimer’s, Parkinson’s and glioblastoma.

Researchers at HM CINAC Comprehensive Neurosciences Centre, in Madrid, explored a technology called low-intensity focused ultrasound (LIFU) – involving non-invasive sound waves – to understand how it can be used to make openings in the blood-brain barrier (BBB).

It is challenging to open up the BBB because the cells that line the blood vessels are tightly packed together, providing a protective layer that keeps foreign substances, including medicines, from entering the brain from the bloodstream.

While LIFU has previously shown promise in temporarily allowing drugs to pass through the BBB, it was not known how LIFU affects the part of the brain that regulates its blood flow (known as the neurovascular unit), or what happens after the BBB is opened to deliver drugs.

By tracking the brains of macaques given the treatment, the study showed that initially mild brain inflammation is triggered and key immune cells activated, but after a week the brain starts to repair itself and new blood vessels grow.

After 30 days, the team found that the neurovascular unit had fully recovered with no signs of lasting damage. It confirmed that LIFU can be a safe way to open the BBB and improve drug delivery for different brain conditions.

In an article for Science X Dialog first author, Tiziano Balzano, said: “LIFU is not just a breakthrough in our understanding of the BBB – it represents a transformative step in how we approach brain treatment as a whole.”