Posts Tagged tACS
[NEWS] Brain stimulation improves depression symptoms, restores brain waves in clinical study — ScienceDaily
Date: March 11, 2019
Source: University of North Carolina Health Care
Summary: With a weak alternating electrical current sent through electrodes attached to the scalp, researchers successfully targeted a naturally occurring electrical pattern in a specific part of the brain and markedly improved depression symptoms in about 70 percent of participants in a clinical study.
With a weak alternating electrical current sent through electrodes attached to the scalp, UNC School of Medicine researchers successfully targeted a naturally occurring electrical pattern in a specific part of the brain and markedly improved depression symptoms in about 70 percent of participants in a clinical study.
The research, published in Translational Psychiatry, lays the groundwork for larger research studies to use a specific kind of electrical brain stimulation called transcranial alternating current stimulation (tACS) to treat people diagnosed with major depression.
“We conducted a small study of 32 people because this sort of approach had never been done before,” said senior author Flavio Frohlich, PhD, associate professor of psychiatry and director of the Carolina Center for Neurostimulation. “Now that we’ve documented how this kind of tACS can reduce depression symptoms, we can fine tune our approach to help many people in a relatively inexpensive, noninvasive way.”
Frohlich, who joined the UNC School of Medicine in 2011, is a leading pioneer in this field who also published the first clinical trials of tACS in schizophrenia and chronic pain.
His tACS approach is unlike the more common brain stimulation technique called transcranial direct stimulation (tDCS), which sends a steady stream of weak electricity through electrodes attached to various parts of the brain. That approach has had mixed results in treating various conditions, including depression. Frohlich’s tACS paradigm is newer and has not been investigated as thoroughly as tDCS. Frohlich’s approach focuses on each individual’s specific alpha oscillations, which appear as waves between 8 and 12 Hertz on an electroencephalogram (EEG). The waves in this range rise in predominance when we close our eyes and daydream, meditate, or conjure ideas — essentially when our brains shut out sensory stimuli, such as what we see, feel, and hear.
Previous research showed that people with depression featured imbalanced alpha oscillations; the waves were overactive in the left frontal cortex. Frohlich thought his team could target these oscillations to bring them back in synch with the alpha oscillations in the right frontal cortex. And if Frohlich’s team could achieve that, then maybe depression symptoms would be decreased.
His lab recruited 32 people diagnosed with depression and surveyed each participant before the study, according to the Montgomery-Åsberg Depression Rating Scale (MADRS), a standard measure of depression.
The participants were then separated into three groups. One group received the sham placebo stimulation — a brief electrical stimulus to mimic the sensation at the beginning of a tACS session. A control group received a 40-Hertz tACS intervention, well outside the range that the researchers thought would affect alpha oscillations. A third group received the treatment intervention — a 10-Hertz tACS electrical current that targeted each individual’s naturally occurring alpha waves. Each person underwent their invention for 40 minutes on five consecutive days. None of the participants knew which group they were in, and neither did the researchers, making this a randomized double-blinded clinical study — the gold standard in biomedical research. Each participant took the MADRS immediately following the five-day regimen, at two weeks, and again at four weeks.
Prior to the study, Frohlich set the primary outcome at four weeks, meaning that the main goal of the study was to assess whether tACS could bring each individual’s alpha waves back into balance and decrease symptoms of depression four weeks after the five-day intervention. He set this primary outcome because scientific literature on the study of tDCS also used the four-week mark.
Frohlich’s team found that participants in the 10-Hertz tACS group featured a decrease in alpha oscillations in the left frontal cortex; they were brought back in synch with the right side of the frontal cortex. But the researchers did not find a statistically significant decrease in depression symptoms in the 10-Hertz tACS group, as opposed to the sham or control groups at four weeks.
But when Frohlich’s team looked at data from two weeks after treatment, they found that 70 percent of people in the treatment group reported at least a 50 percent reduction of depression symptoms, according to their MADRS scores. This response rate was significantly higher than the one for the two other control groups. A few of the participants had such dramatic decreases that Frohlich’s team is currently writing case-studies on them. Participants in the placebo and control groups experienced no such reduction in symptoms.
“It’s important to note that this is a first-of-its kind study,” Frohlich said. “When we started this research with computer simulations and preclinical studies, it was unclear if we would see an effect in people days after tACS treatment — let alone if tACS could become a treatment for psychiatric illnesses. It was unclear what would happen if we treated people several days in a row or what effect we might see weeks later. So, the fact that we’ve seen such positive results from this study gives me confidence our approach could help many people with depression.”
Frohlich’s lab is currently recruiting for two similar follow-up studies.
Other authors of the Translational Psychiatry paper are co-first authors Morgan Alexander, study coordinator and graduate student, and Sankaraleengam Alagapan, PhD, a postdoctoral fellow, both in the department of psychiatry at UNC-Chapel Hill; David Rubinow, MD, the Assad Meymandi Distinguished Professor and Chair of Psychiatry at the UNC School of Medicine; former UNC postdoctoral fellow Caroline Lustenberger, PhD; and Courtney Lugo and Juliann Mellin, both study coordinators at the UNC School of Medicine.
This research was funded through grants from the Brain Behavior Research Foundation, National Institutes of Health, the BRAIN Initiative, and the Foundation of Hope.
Frohlich holds joint appointments at UNC-Chapel Hill in the department of cell biology and physiology and the Joint UNC-NC State Department of Biomedical Engineering. He is also a member of the UNC Neuroscience Center.
- Morgan L. Alexander, Sankaraleengam Alagapan, Courtney E. Lugo, Juliann M. Mellin, Caroline Lustenberger, David R. Rubinow, Flavio Fröhlich. Double-blind, randomized pilot clinical trial targeting alpha oscillations with transcranial alternating current stimulation (tACS) for the treatment of major depressive disorder (MDD). Translational Psychiatry, 2019; 9 (1) DOI: 10.1038/s41398-019-0439-0
[Abstract] Basic and functional effects of transcranial Electrical Stimulation (tES)—An introduction
[REVIEW] TRANSCRANIAL DIRECT CURRENT STIMULATION (tDCS) AND TRANSCRANIAL CURRENT ALTERNATING STIMULATION (tACS) REVIEW – Full Text PDF
This literature review is aimed to explore the main technical characteristics of both transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) using the latest research on both healthy and impaired subjects. These techniques have no oﬃcial standards developed yet. Our intent is to underline the main properties and problems linked with the application of those techniques which show diverse, and sometimes even opposite, results depending mainly on electrode positioning and underlying brain activity.
Among diﬀerent impairments that can aﬀect standard brain functions, we choose to focus primarily on stroke, because it is one of the most prevalent and severe disability worldwide . It is known that after a cerebrovascular accident, reorganization of neural tissues takes place . If the ischemic event occurs on the motor area and it is severe enough to block the spontaneous neural reorganization, it could lead to paresis or even paralysis of one or more body parts .
In order to ameliorate stroke rehabilitation, diﬀerent approaches have been carried out. Over the last decade, within the ﬁeld of functional rehabilitation, transcranial current stimulation (tCS) has garnered considerable attention. It is assumed to improve, above other, motor functions in both healthy and stroke individuals , , .
There are three diﬀerent types of tCS: transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS) and random noise stimulation (tRNS). All of them are non-invasive and involve low intensity current induction into the brain. Some studies have investi
gated the physiological basis of tDCS and tACS in order to get the picture of standard pattern that can be used for future research , .
This paper is oriented towards a broad audience who wants to understand the basic mechanisms of tDCS and tACS techniques. The main parameters of each type of stimulation and the implications related to its application on healthy subjects, stroke patients and individuals with unusual brain oscillations are discussed.
Low-intensity transcranial electrical stimulation (tES) methods are a group of noninvasive brain stimulation techniques, whereby currents are applied with intensities typically ranging between 1 and 2 mA, through the human scalp. These techniques have been shown to induce changes in cortical excitability and activity during and after the stimulation in a reversible manner. They include transcranial direct current simulation (tDCS), transcranial alternating current simulation (tACS), and transcranial random noise stimulation (tRNS).
Currently, an increasing number of studies have been published regarding the effects of tES on cognitive performance and behavior. Processes of learning and increases in cognitive performance are accompanied by changes in cortical plasticity. tES can impact upon these processes and is able to affect task execution. Many studies have been based on the accepted idea that by increasing cortical excitability (e.g., by applying anodal tDCS) or coherence of oscillatory activity (e.g., by applying tACS) an increase in performance should be detected; however, a number of studies now suggest that the basic knowledge of the mechanisms of action is insufficient to predict the outcome of applied stimulation on the execution of a cognitive or behavioral task, and so far no standard paradigms for increasing cortical plasticity changes during learning or cognitive tasks have been established.
The aim of this review is to summarize recent findings with regard to the effects of tES on behavior concentrating on the motor and visual areas…
Is transcranial current stimulation (tCS, including direct current, tDCS, alternating current, tACS, or random noise stimulation tRNS) effective for the treatment of depression?
Under what conditions? With what montages? We focus here on a review of the recent literature on this topic. We have relied on Google Scholar and also PubMed to carry out the search, including the terms of tDCS, tACS, tRNS as well as Depression (from March 2012 and till Sep 2013).
As you can read below, there quite a few encouraging results in this area, and study group sizes (the famous N) are moderately large. We try to indicate group size and the use of a sham-controlled, double-blind experimental technique. Most studies are careful about these crucial aspects. In addition, it is worth mentioning that there continues to be a lack of bad news from the safety point of view. This seems to be a common pattern of tDCS research (or tCS, in fact). I will discuss this further in a future post on an update on tCS Safety.
The typical target for treatment is anodal on the left DLPFC (F3 in the 10-20 EEG system) with the cathode over the contralateral orbit or, sometimes, over the right DLPFC. As in prior posts, in what follows we concentrate on relevant, study-oriented papers with patients, and leave reviews to the end. In order to make the reading lighter, we have edited the abstracts a bit (please click on the title link if you are interested in the paper)… Full Text PDF