For years, many sufferers of Parkinson's They have benefited from the possibility of stimulating their brain with electrical impulses. Many doctors have tried to use similar techniques to change the mood of depressed people, but attempts to prove their effectiveness on a large scale have had limited effects. When deep brain stimulation is applied in small groups of patients, in phases of initial study, the results are promising, sometimes even surprising, because in a short time they can make people who have been depressed for years feel better. In fact, according to the agency SINC Daamian Denys, a researcher at the University of Amsterdam (Netherlands), the main problem of treatment may be its effectiveness. "Imagine that you are a father of a family with a wife and children and that you have been depressed and prostrate on the sofa for the past 30 years. You start the treatment and suddenly one day you arrive home and you are active, you are interested in everything, you go out and buy tickets to Paris for the whole family because you want to see the Louvre. The symptoms disappear and people really change a lot in a very short time. For the family, work and the environment in general, this change is so brutal that it can even produce a sense of threat, "he argued. When the treatment is tested in large trials, however, the difficulties to prove its effectiveness they are still important.
Today, a team of researchers from the University of California at San Francisco (UCSF), in the United States, once again show promising results against depression in a small group of patients treated with electrical stimuli. In an article that is published in the magazine Current Biology, explain how they stimulated Orbitofrontal cortex lateral, a region that is located on the eye sockets and that is related to the processing of emotions and reward. As explained by the authors, the electrical impulses improved the mood of the patients and produced an activity similar to that observed in a person who experiences a good mood. In some way, the stimulation returned the circuits related to the mood to its proper functioning.
Deep brain stimulation is invasive and only applies in people who do not respond to other treatments for depression
To improve the mood of depressed patients, we have searched for the most appropriate regions for each type of patient, but, according to Kristin Sellers, UCSF researcher and co-author of the study, "our understanding of depression is not good enough even to achieve that kind of personalization ", although it is hoped that it will be. At the moment, "there are multiple targets for stimulation that could help with the symptoms." "This can be like entering a highway. There are several ramps that can take you to the road you want to reach, "he explains.
Studying the effects of electrical stimulation has important limitations. On the one hand, to implant the electrodes with which to apply it, it is necessary that patients undergo surgery, an invasive intervention that leaves this option only for people with depressions that do not respond to more conventional treatments such as drugs. In the study published today, to explore the orbitofrontal cortex as a target for electrical stimulation, the researchers took advantage of a group of 25 people with epilepsy who had already been implanted electrodes to find the source of their outbreaks and, in addition, of schizophrenia, suffered from depression. "A question we must answer is whether the stimulation of this region also relieves the symptoms of people with depression but without epilepsy." In addition, they should propose trials in which patients are followed for a long period of time and not only observe the relief for a week or two, as was done with this study.
While the areas of the brain are better understood and which are ideal for stimulation, devices are being developed that allow it to be applied without surgery. Finding more accessible regions will also facilitate the implementation of this less invasive technology.
In Spain, there are few centers in which surgery is performed to place electrodes and treat depression with electrical impulses. Marta Navas, neurosurgeon at the Hospital de la Princesa, in Madrid, explains that along with her partner Cristina Torres they have operated three people. Two of them had a surprising recovery and a third responded well to the surgery, but is still in the follow-up period. "These patients require significant vigilance, often need adjustments and surgeons have to cooperate with psychiatrists to perform them," says Navas. "One of these patients, for example, started to feel bad and it was because he had run out of the device's battery," he says. Although he considers that this type of treatment is effective, Navas points out some reluctance on the part of psychiatrists to leave patients in their hands. "Patients have to be well selected and must meet appropriate criteria, but the therapy is safe," concludes Navas.