Transcranial direct current stimulation (tDCS), an affordable and portable way to stimulate the brain, can help induce normal neural activity and make thought processes more flexible in people with schizophrenia, according to a study published online June 29th in Proceedings of the National Academy of Sciences.
“This paper is one of the best examples of using tDCS to improve cognitive deficits in a mental disorder,” said Kevin Spencer, Ph.D., of Harvard University, who was not involved in the study. “This shows the promise of these non-invasive stimulation methods.”
The study suggests a drug-free and safe way of treating debilitating cognitive problems, for which antipsychotics are not completely effective.
Among these cognitive impairments are problems with learning from mistakes and adapting to changing conditions. In lab tests, people with schizophrenia may stick with wrong answers or strategies even if the outcome is not successful. They do not tend to slow down to reconsider their responses after making a mistake. These difficulties can interfere with learning at all levels.
“In order to optimally interact with our complicated environment, we constantly adjust our behavior,” explained 2012 NARSAD Distinguished Investigator, Sohee Park, Ph.D., who led the study with Geoffrey Woodman, Ph.D., both at Vanderbilt University. “Normally we do it automatically,” she said, “but people with schizophrenia have difficulty adjusting ongoing behavior. This results in inflexibility of actions and thoughts. Importantly, they may not even notice their errors when they make them.”
Twenty minutes of low-voltage tDCS applied to the scalp over the medial prefrontal cortex improved error-monitoring and accuracy in a test of adaptive control in people with schizophrenia. In addition, after stimulation, specific brain waves measured by scalp electrodes were observed to “normalize,” by showing greater synchrony, in this way more resembling patterns seen in healthy controls.
In a commentary accompanying the paper, Foundation Scientific Council Member and 2007 NARSAD Distinguished Investigator Cameron Carter, M.D., of the University of California in Davis, wrote that “these findings reinforce our growing understanding that the disordered brain is not locked away inside the skull as we once thought, but is indeed within our reach and accessible for neuromodulation.”