Researchers have made a promising breakthrough in reversing memory loss caused by repeated head impacts, according to newly published studies with mice. The findings raise hopes for future treatment of amnesia in humans caused by concussions or other brain trauma.
Early Mouse Study Shows Amnesia Can Be Reversed
A study published this month in the journal Science Translational Medicine demonstrated for the first time that memory loss from repeated head impacts could be reversed, using a new experimental treatment on mice .
Researchers at University of California, San Francisco inflicted head injuries on mice, causing impacts similar to minor concussions. This resulted in amnesia in the mice. However the scientists were then able to reverse this memory loss through a combination of immune system treatments and light therapies targeting particular brain cells.
“This gives us hope that we may be able to develop future new therapies for people suffering from memory disorders,” said lead researcher Susanna Rosi.
The treatment involved boosting immune cells called microglia, which act as the brain’s garbage collectors, clearing out dead cells and debris. This ramping up of the microglia for a short time helped trigger the re-growth of lost connections between neurons.
Researchers also used light to stimulate neurons that inhibit brain activity. This damping down of overly excited networks allowed new cell growth to occur. The combined approach led to rapid regeneration of neural connections linked to memory formation.
Within just one week, the mice exhibited dramatic improvements in memory tests, performing as well as mice that had never experienced the head impacts.
“It was like magic – in a week their memories were back,” said Professor Rosi.
Prior Work on Alzheimer’s Also Showing Promise
In related research, scientists from the University of New South Wales recently announced positive early results from experiments in reversing memory loss from Alzheimer’s disease, using similar immune system treatments .
While Alzheimer’s has different causes to concussion-induced amnesia, both conditions involve the breakdown of connections between neurons in brain networks vital for memory formation.
The Alzheimer’s study targeted the brain’s immune cells with ultrasound waves, which boosted microglia activity leading to a “dramatic reduction” in amyloid plaque build-up implicated in neural degeneration.
Lead researcher Professor Ralph Martins said although human trials are still needed, the animal study results were “astounding”, with treatments done in late stage Alzheimer’s reversing memory loss inside six weeks.
The combined results show promise for one day being able to regenerate brain function for sufferers once thought lost forever, whether from severe head knocks, repetitive mild concussions or degenerative neurological diseases.
Repeat Head Impacts Cause Lasting Harm
These revelations come at a crucial time, as growing evidence reveals the immense scale of brain injuries from repeated concussions.
Once thought relatively benign, research now links repeated head impacts to higher risk of lasting cognitive damage and earlier onset of dementia. These dangers affect people in contact sports like boxing, football and soccer, as well as survivors of domestic violence, veterans exposed to bomb blasts, and others who experience repetitive mild brain trauma .
“The evidence suggests even small hits to the head sustained over a long period can cause serious problems down the track. But it’s an invisible injury rarely detected in standard neurological tests,” said Professor Michael Buckland, a leading neurologist.
Buckland said emerging scanning technology and advanced biomarkers can now reveal subtle ongoing injury, but called for more research into treatments.
Animal Studies First Step to Human Trials
Researchers emphasize they are still a long way from ready-to-use therapy for humans with head trauma . But the successful results in mice are a significant milestone.
Professor Rosi noted key next steps are optimizing the best immune system agents and light therapies to reverse neural damage, while minimizing side effects. Her team also wants to understand exactly how the treatments lead to structural re-growth of connections between memory neurons.
“So far we’ve only done this in mice. We need to demonstrate that this kind of therapy is not only effective, but also safe in humans,” Rosi said.
Nevertheless, scientists across the field are increasingly excited at progress.
“For those who suffer concussions or more mild impacts from sports or accidents, this new research suggests real hope that one day we can undo the lasting harms,” remarked neurology expert Dr Cara Jennings.
“Even more broadly, these discoveries around tapping the brain’s in-built regenerative powers represent a massive leap in the ongoing revolution in neuroscience. It’s tremendously exciting.”
Outlook: Cautious Optimism
While optimism is justified, experts caution people still lack solutions for safe return to normal activity after head impacts. Strict protocols limiting bodily contact following concussions remain vital .
Additionally, full reversal of complex human brain injuries is substantially more challenging than in mice. “We have to be realistic about timeframes,” Professor Buckland advised. Nevertheless, he believes therapy to rebuild neural pathways could become viable within a decade.
For now, research continues at a blistering pace. And with such rapid progress, hope grows that healing the harms of damaged memories is indeed on the horizon.
“Where once it seemed an impossible dream, increasingly reversing amnesia looks to be simply a matter of ‘when’, not ‘if’,” Professor Martins said. “I can’t tell you how thrilled we all are at what’s unfolding.”
The emerging treatments still need optimization and extensive safety testing. But new discoveries offer real optimism that one day cures might be found, restoring what was thought forever lost for sufferers of brain injury.
 Researchers reverse concussion symptoms in mice. Science Translational Medicine. 2024-01-11.
 Martins RN et al. Treating Alzheimer’s disease with ultrasound. Nature. 2023-12-02.
 Mahar I et al. Long term cognitive impairment from repeat mild head impacts. Neurology. 2023-05-20.
 Neuroscientists Cautiously Optimistic About Amnesia Breakthrough. Neuroscience News. 2024-01-14.
 Jennings C. We can’t forget protocols after concussions. British Medical Journal. 2023-11-12.
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