Traumatic brain injuries have left more than five million Americans with permanent disabilities. They have trouble concentrating on even simple tasks and often have to quit their jobs or drop out of school.
A published study Monday has offered them a glimmer of hope. Five people with moderate to severe brain injuries had electrodes implanted in their heads. As the electrodes stimulated their brains, their performance on cognitive tests improved.
If the results hold up in larger clinical trials, the implants could become the first effective therapy for chronic brain injuries, the researchers said.
“This is the first evidence that you can turn the dial on this problem,” said Dr. Nicholas Schiff, a neurologist at Weill Cornell Medicine in New York, who led the study.
Gina Arata, one of the volunteers who received the implant, was 22 years old when a car accident left her with fatigue, memory problems and uncontrollable emotions. She abandoned her plans to study law and lived with her parents in Modesto, California, unable to hold a job.
In 2018, 18 years after the accident, Arata received the implant. His life has changed profoundly, she said. “I can be a normal human being and have a conversation,” she said. “It's amazing how I've seen myself improve.”
Dr. Schiff and his colleagues designed the trial based on years of research on brain structure. Those studies suggested that our ability to focus on tasks depends on a network of brain regions that are linked together by long branches of neurons. The regions send signals to each other, creating a feedback loop that keeps the entire network active.
Sudden jolts to the brain (in a car accident or a fall, for example) can break some of the long-distance connections in the network and lead people to fall into a coma, Dr. Schiff and his colleagues have hypothesized. . During recovery, the network may be able to turn back on. But if the brain is severely damaged, it may not fully recover.
Dr. Schiff and his colleagues identified a structure deep in the brain as a crucial hub of the network. Known as the central lateral nucleus, it is a thin sheet of neurons about the size and shape of an almond shell.
The human brain has two such structures, one in each hemisphere. They appear to help the brain calm down for sleep at night and rev it up in the morning. Stimulate neurons in these regions. can wake up a sleeping ratas Dr. Schiff's research has shown.
These studies raised the possibility that stimulation of the central lateral nuclei could help people with traumatic brain injuries regain their concentration and attention.
Surgeons regularly implant electrodes in patients with Parkinson's disease. The small electrical pulsesReleased by the implants hundreds of times per second, it directs neighboring neurons to send their own signals, restoring some of the brain's functions.
In 2018, Dr. Schiff and his colleagues began recruiting volunteers, like Ms. Arata, who suffered from chronic problems for years after her accidents. Before inserting the electrodes, the researchers gave the volunteers a series of tests to judge their ability to concentrate and switch tasks. In one test, for example, volunteers were each given a sheet of paper filled with letters and numbers and had to draw a line joining them in order as quickly as possible.
Before surgery, researchers scanned each volunteer's brain to create an accurate map. Dr. Jaime Henderson, a neurosurgeon at Stanford University, guided the electrode through the brain to the central lateral nucleus.
Dr. Henderson implanted the electrodes in six volunteers, but one of them had to leave the study after developing a scalp infection. One month after surgery, the five remaining volunteers performed follow-up tests. On the letter and number test, their scores increased between 15 and 52 percent.
To gain a broader understanding of the volunteers' experiences, Dr. Joseph Fins, a medical ethicist at Weill Cornell Medicine, conducted a interview series with them and their families. Most of the volunteers, like Ms. Arata, said the implant made them closer to who they were before.
The volunteer who saw the greatest improvement on the cognitive tests, on the other hand, had a lukewarm reaction. “I don't think it hurt,” he said. “I just don't know if it helped much.”
And yet, that patient's son observed significant changes, especially in his father's self-awareness. “It's day and night,” said the son.
Dr. Steven Laureys, a neurologist at the University of Liège in Belgium, who was not involved in the study, said the results supported the theory that attention and other forms of thinking depend on the brain network. “There's enough reason to believe it's worth pursuing,” he said of the investigation.
Dr. Schiff and his colleagues are planning a much larger study of brain implants. “We have to see how the data reflects,” he said.
The central lateral nuclei are not the only regions that show promise as hubs of the brain network, said Dr. Alex Green, a neurosurgeon at the University of Oxford who was not involved in the study.
“We still don't know where the best place to stimulate is,” Dr. Green said. He and his colleagues are setting up their own brain injury trial to test electrodes in a region called the pedunculopontine nucleus.
Dr. Laureys acknowledged that implant surgeries would be expensive, but argued that society should recognize the millions of people who suffer traumatic brain injuries. “This is a silent epidemic,” he said.
