First, participants donned EEG monitors and performed a challenging cognitive control task specifically designed to trip them up. “We saw a beautiful burst of low-frequency activity [from the medial-frontal cortex] right after someone made a mistake,” said Reinhart. “But it was deficient in our patients with schizophrenia.”
In healthy individuals, these theta waves were steady and synchronized, but in people with schizophrenia, the waves were weak and disorganized, suggesting that they were having a harder time processing the mistake. And the subjects’ behavior bore that out—the healthy subjects slowed down by a few milliseconds when they made mistakes and did better in the next round, while the subjects with schizophrenia did not.
After tDCS, the picture was dramatically different. The electrical stimulation to the scalp significantly improved the strength and synchrony of the brain waves in both groups but most notably in people with schizophrenia. “The results of our study clearly indicate that it is possible to restore error-monitoring in people with schizophrenia with tDCS,” said Park.
Known as transcranial direct current stimulation (tDCS), the process involves attaching electrodes to the skull and targeting specific areas of the brain with calculated jolts of electricity.
“The brain is an electrical organ, so it makes sense to try to manipulate what’s going on in the brain with electricity,” explains neuroscientist Dr. Michael Weisend.
One unusually well-designed study, he said, was from the University of Lyon in France, in which 30 people with schizophrenia reported that after TDCS, they heard voices about 30 percent less than before. The researchers followed up with the patients, and the treatment was still working, even after three months.
Frohlich decided that the schizophrenia study was so potentially life-changing for patients that it had to be replicated — and improved upon — as quickly as possible. According to the National Institutes of Health, about 1 percent of Americans have schizophrenia; many of them are too sick to work or even talk lucidly with their doctors about treatment. Antipsychotic medication helps some, but it has serious side effects. A 2013 study estimated that the costs of schizophrenia — from treatment to caregiving and unemployment — are about $4 billion a year in the U.S.
Neurobiological Effects of Transcranial Direct Current Stimulation: A Review
The purpose of this systematic review is to summarize the current knowledge regarding the neurobiological mechanisms involved in the effects of tDCS.
Neuroenhancement of the aging brain: restoring skill acquisition in old subjects.
The main finding was that old participants experienced substantial improvements when training was applied concurrent with tDCS, with effects lasting for at least 24 hours.
Examining transcranial direct-current stimulation (tDCS) as a treatment for hallucinations in schizophrenia.
Auditory verbal hallucinations were robustly reduced by tDCS relative to sham stimulation…
Modulation of training by single-session transcranial direct current stimulation to the intact motor cortex enhances motor skill acquisition of the paretic hand.
tDCS facilitated the acquisition of a new motor skill compared with sham stimulation…
Interactions between transcranial direct current stimulation (tDCS) and pharmacological interventions in the Major Depressive Episode: Findings from a naturalistic study.
tDCS over the DLPFC acutely improved depressive symptoms…
Amelioration of cognitive control in depression by transcranial direct current stimulation.
Deficient cognitive control over emotional distraction is a central characteristic of major depressive disorder (MDD)
The present study demonstrates that anodal tDCS applied to the left dlPFC improves deficient cognitive control in MDD.
Transcranial direct current stimulation of the motor cortex in the treatment of chronic nonspecific low back pain: a randomized, double-blind exploratory study.
No significant effect was seen in the primary outcomes between active and sham stimulation
Comparing immediate transient tinnitus suppression using tACS and tDCS: a placebo-controlled study.
…bifrontal tDCS modulates tinnitus annoyance and tinnitus loudness, whereas individual alpha-modulated tACS does not yield a similar result.
Review of transcranial direct current stimulation in poststroke recovery.
In this review, we summarize characteristics of tDCS (method of stimulation, safety profile, and mechanism) and its application in the treatment of various stroke-related deficits, and we highlight future directions for tDCS in this capacity.
Results: Auditory verbal hallucinations were robustly reduced by tDCS relative to sham stimulation, with a mean diminution of 31% SD=14; d=1.58, 95% CI=0.76–2.40. The beneficial effect on hallucinations lasted for up to 3 months. The authors also observed an amelioration with tDCS of other symptoms as measured by the Positive and Negative Syndrome Scale d=0.98, 95% CI=0.22–1.73, especially for the negative and positive dimensions. No effect was observed on the dimensions of disorganization or grandiosity/excitement.
Conclusions: Although this study is limited by the small sample size, the results show promise for treating refractory auditory verbal hallucinations and other selected manifestations of schizophrenia.