Brain Implants Revive Cognitive Abilities Long After Traumatic Brain Injury

Moderate to severe traumatic brain injury often leave individuals struggling with challenges such as focusing, memory retention, and decision-making. While many of them manage to live independently, their cognitive impairments frequently hinder their ability to return to work, school, or social activities. Notably, these patients often recover from comas and regain a significant level of cognitive function, suggesting the preservation of brain systems responsible for attention and arousal. These systems, crucial for staying alert and focusing on tasks or conversations, involve connections between the thalamus—a central brain relay station—and the cortex, which governs higher cognitive functions. The central lateral nucleus within the thalamus, in particular, regulates numerous aspects of consciousness. Now, a device surgically implanted deep inside the brain to deliver precise electrical stimulation of the central lateral nucleus and its connections has been found to reactivate these pathways, restoring the cognitive abilities lost to brain injuries.

The new technique, developed by researchers at Stanford Medicine (Stanford, CA, USA), in collaboration with other institutions, is the first to demonstrate potential against long-lasting impairments from moderate to severe traumatic brain injuries. In the clinical trial, the research team recruited five participants aged 22 to 60, who had sustained traumatic brain injuries between three to 18 years prior. These individuals had ongoing cognitive impairments despite the time elapsed since their injuries. The primary challenge for the researchers was the precise placement of the experimental deep-brain-stimulation device within the brain, as each participant's brain was uniquely shaped and further altered by their injuries. Utilizing virtual models of each individual's brain, the researchers accurately determined the stimulation's location and intensity to activate the central lateral nucleus. This precision allowed for the successful surgical implantation of the devices in the participants.

During the trial, participants had the device turned on for 12 hours daily over a 90-day period, following a two-week titration phase to fine-tune the stimulation. Their progress was evaluated using the trail-making test, a standard measure of mental processing speed involving the connection of scattered letters and numbers. Remarkably, at the trial's conclusion, the participants had improved their test speeds by an average of 32%, surpassing the researchers' initial target of 10%. This improvement was not just a statistic; it significantly impacted their daily lives. Participants were able to resume activities like reading, watching TV, playing video games, and completing homework, felt less tired, and managed their days without the need for naps.

However, the trial participants faced a challenge in its final phase, a planned blinded withdrawal segment where half of them would unknowingly have their devices turned off. Two participants opted out, not willing to risk losing their newfound improvements. Of the three who continued, one had their device deactivated, leading to a 34% slower performance on the trail-making test after three weeks without stimulation. This clinical trial marks the first to target the brain's specific region in patients with moderate to severe traumatic brain injuries. It brings new hope to many who have seen their recovery plateau, offering a potential path to reclaim aspects of their lives affected by their injuries.

“This is a pioneering moment,” said Nicholas Schiff, MD, a professor at Weill Cornell Medicine and co-senior author of the study. “Our goal now is to try to take the systematic steps to make this a therapy. This is enough of a signal for us to make every effort.”

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