San Diego (California), Feb 20 (DPA) Researchers at 17 US medical centres plan to start using a hormone to treat serious brain injuries on a trial basis, according to a presentation Friday at an annual US gathering of scientists.

Initial studies have showed that progesterone, a steroid hormone involved in the female menstrual cycle and pregnancy, can cut the death rate from traumatic brain injury (TBI) in half.

The final phase of the clinical trials, which is to begin in March, is being funded by the National Institutes of Health through Emory University in Atlanta, Georgia, it was announced at the annual gathering of the American Association for the Advancement of Science (AAAS) in San Diego.

David Wright, professor of emergency medicine at Emory’s Medical School, is leading the clinical trial, which will enroll 1,140 people over the next three to six years starting in March.

“No new treatment for severe TBI has been approved in over 30 years,” Wright said in a statement. He said he hoped the trial would prove that progesterone, along with standard medical trauma care, “works better than standard medical care alone” in reducing brain damage from TBI.

An earlier trial on about 100 patients showed a 50-percent drop in death in patients treated with progesterone. The hormone also reduced long-term disability, and disability in patients with milder brain injuries.

Donald Stein, another emergency medicine professor at Emory, pioneered studies into the neuro-protective properties of progesterone 25 years ago in testing on laboratory animals.

He found that male rats suffered more from brain trauma than female rats, especially when the female rats were in the reproductive phase when their body was producing more progesterone.

Stein then injected progesterone into male rats recovering from brain trauma and found their death rate sank drastically and they returned to full mobility much sooner.

Progesterone is naturally present in small but measurable amounts in the brains of males and females, and human brain tissue has a large amount of receptors for the hormone.

An estimated 2 million adults and children suffer traumatic brain injuries every year in the US, leading to 50,000 deaths and 80,000 cases of long-term disability, according to the Centers for Disease Control and Prevention.