US scientists undo memory loss in brain-damaged mice

By Barry Eitel

SAN FRANCISCO

Scientists for the first time have completely reversed memory loss resulting from traumatic brain injuries (TBI) in mice, a team of researchers announced Monday.

Researchers hope the breakthrough will lead to new therapies for humans suffering from head trauma.

An experimental new drug, ISRIB, restored the ability to learn and remember in brain-damaged mice. More strikingly, the drug appeared to work even when the injuries were a month old.

Approcimately 2 million Americans sustain a TBI every year, according to statistics from the Centers for Disease Control and Prevention, but the number is likely much higher because many sufferers do not go to the emergency room.

While about 52,000 die annually from TBI, about 80 percent are released and can suffer longstanding mental health effects. Brain injuries are a leading risk factor for Alzheimer’s disease and dementia.

In a paper published in the journal The Proceedings of the National Academy of Sciences, scientists at the University of California in San Francisco (UCSF) believe ISRIB, which was discovered in 2013, may help many sufferers.

“This is extraordinarily exciting,” said Peter Walter, who discovered ISRIB and is co-senior author of the UCSF study, in a statement. “We think that ISRIB may uncover an untapped reservoir in the brain that allows damaged memory circuits to be repaired.”

Researchers found ISRIB was effective in reversing the effects of two different types of brain injuries: localized brain injuries, in which only certain regions of the brain are damaged, and concussive brain injuries, when the trauma effects the entire brain.

The former can result in issues with spatial memory essential for conducting everyday tasks, while the latter can damage “working memory” – sort-term thinking that is crucial for reasoning.

“In general, animals with these injuries never learn well again,” Susannah Rosi, the other co-senior author, said in a statement. “So it’s remarkable that ISRIB could restore the ability to form new memories even when we delayed giving the drug for four weeks after the injury. This has not been considered possible.”

Rosi and Walter plan to do more research on mice before attempting a clinical trial of ISRIB on humans with TBI.