There is new evidence that mild electrical impulses can relieve depression if they reach the right target in the brain.
A study of 25 people with epilepsy found that those with symptoms of depression felt better almost immediately when doctors electrically stimulated an area of the brain just above the eyes, a team reported Thursday. the newspaper Current biology.
These people were in hospital waiting for surgery and had wires inserted into their brains to help doctors locate the source of their seizures.
Kristin Sellers, author of the journal and postdoctoral researcher at the University of California at San Francisco, said that many of the patients had talked about the change they had felt when stimulating the lateral orbito-frontal cortex. One person replied, "Wow, I feel a lot better … What did you do?"
The stimulation lasted only a few minutes. After stopping, the effect on mood quickly faded.
To be sure the effect is real, the researchers also claimed to stimulate lateral OFCs in the same patients without passing current through the tiny wires implanted in their brains. In these fictitious treatments, there was no discernible change.
The results add to the evidence that patients with depression can be helped with an approach known as deep brain stimulation.
DBS is an approved treatment for tremors, including those associated with Parkinson's disease. But the results with depression have been less consistent and the DBS has not been approved for this purpose by the Food and Drug Administration.
The latest study represents "another piece of a very complicated puzzle, a very important piece," says Helen Mayberg, a pioneer in the use of CPS to treat depression.
The study also provides strong evidence that boosting the OFC can temporarily improve the mood of a depressed person, says Mayberg, who runs the Center for Advanced Circuit Therapeutics, part of the Mount Sinai Health System in New York.
But it's not clear if stimulation can produce lasting change, she says. In addition, the study could not answer a critical question because it only included people reporting transient symptoms of depression.
"What will happen if you do this in people who have actually failed all types of treatment for a major depressive episode and who are chronically and insecurely ill," said Mayberg.
At the same time, his own team was able to help about 80% of these patients by stimulating a different area of the brain – a region that shares many connections with the OFC.
The latest study offers "more evidence than [DBS] is something real that will work for depression, "says Al Fenoy, an associate professor of neurosurgery at the University of Texas Health Sciences Center in Houston.
Fenoy is part of a team that has successfully treated depression by stimulating another area of the brain that shares links with the OFC. "We are all working in the same direction," he says. "One of the common denominators could be this orbitofrontal area."
But it's also possible that different types of depression require different targets, Fenoy says.
All research on brain stimulation reflects an increasingly older tendency to think that depression is caused by a chemical imbalance in the brain.
"A more modern conception sees depression as a malfunction of the circuit, which means that the way brain cells talk to each other does not quite fit the right," says Dr. Vikram Rao, author of the new study and a Assistant Professor of Clinical Neurology at UCSF.
Researchers have therefore tried to identify faulty circuits and improve them by using electrical pulses. The challenge has been to find areas that have a very good connection to the faulty circuit
"What I like to think about is that we are trying to take a freeway and that there are a lot of different ramps," Sellers said.
The UCSF team has taken an innovative approach in this regard by studying patients with epilepsy who are waiting for surgery. This meant that they already had wires inserted into their brains to help doctors locate the source of their seizures.
In a previous related study, UCSF researchers had used a different group of patients with epilepsy to identify circuits in the brain indicating whether people were happy or sad. This time, they were able to use these cables not only to monitor various brain circuits involved in mood, but also to electrically stimulate some of these areas.
Researchers have been able to use this technique in many areas of the brain. And Sellers said it received an immediate response by boosting the OFC.
"What we have found is that, consistently, lateral OFC stimulation improves the mood of symptomatic patients," says Sellers. In addition, more powerful stimulation resulted in a more dramatic improvement in mood, she said. There was no problem with side effects, including mania, which was seen in some previous experiences with brain stimulation.
This is probably because the OFC offers very good access to the brain networks involved in depression, says Rao. "It seems like a crossroads to connect many areas of the brain involved in regulating our mood," he says.
And Rao says the results suggest that pacing this area improves the function of a faulty circuit, rather than making everyone happier.
"Only people who had symptoms [of depression] to start improving their mood, suggesting that the effect of what we are doing is normalizing activities that start abnormally, "said Rao.