Electrical Stimulation Helps Improves Cognition In Individuals With Schizophrenia
According to a new study from Vanderbilt University, individuals with schizophrenia show improved cognition after receiving mild electrical stimulation to the brain. Specifically, after receiving a small zap, the participants in the study were able to recognize recent errors and make appropriate corrections in ways individuals without the condition can.
Schizophrenia is characterized by poor cognitive control which can create difficulties in working memory, attention, focus, and error-monitoring. Error monitoring can be measured by “post-error slowing” or the almost undetectable pause healthy individuals take after making an error, such as a typo.
“It has been known for decades that error-monitoring is reduced in individuals with schizophrenia,” said Dr. Sohee Park, Gertrude Conaway Vanderbilt Professor of Psychology, who contributed to the research. “This impairment has been extremely difficult to remediate.”
Past research has indicated post-error slowing can be improved by applying low-voltage electrical currents called transcranial direct stimulation (tDCD) to the medial-frontal cortex, a region of the brain linked with cognitive control.
In this study, published in the Proceedings of the National Academy of Sciences, participants performed a challenging cognitive control task while wearing EEG monitors. “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.”
When healthy participants performed the task their theta waves appeared steady and synchronized, but for individuals with schizophrenia the waves were weak and disorganized. The researchers say this suggests the individuals were having trouble processing the mistake.
The scientists say the difference was also noticeable in physical behavior. When healthy subjects made mistakes, they slowed down by a few milliseconds and performed better in the following test. Individuals with schizophrenia did not.
After administering electrical stimulation, however, the results were different. Both groups showed strengthened and more organized brain waves, but the effect was particularly pronounced in individuals with schizophrenia.
“We found that medial-frontal stimulation resulted in normalization of patients’ post-error slowing such that their performance was identical to that of healthy control subjects at baseline,” the researchers wrote.
“The global burden of schizophrenia is greater than that of untreated AIDS, metastatic cancer or severe dementia,” said Park. “The results of our study clearly indicate that it is possible to restore error-monitoring with tDCS.”
According to the researchers, the results could have big implications for treatment of schizophrenia.
“Cognitive deficits in people with schizophrenia are treated with drugs, without significant success,” Park said. “But I want to emphasize that there is much work to do before we can be certain that tDCS can be used as a treatment. We need to work out why and how these changes occur, how long these effects last and whether there are other consequences.”