Schizophrenia patients who receive light electrical stimulation to the brain experience an improvement in short-term memory, according to a new study at the Johns Hopkins University School of Medicine.
The technique, called transcranial direct current stimulation, involves placing sponge-covered electrodes on the head and passing a weak electrical current between them. The procedure is widely recognized as safe and is being studied as a treatment for depression, Alzheimer’s-related memory loss, and for helping people recover from strokes.
The researchers hypothesize that this type of brain stimulation might ease some of the cognitive difficulties that afflict people with schizophrenia.
“Cognitive impairment is as ubiquitous as hallucinations in schizophrenia, yet medications only treat the hallucinations. So even with medication, affected individuals often remain very disabled,” said David Schretlen, Ph.D., a professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.
He hopes that transcranial direct current stimulation could give people with schizophrenia a shot at leading a more normal life.
For the study, Schretlen and five Johns Hopkins colleagues targeted a brain region called the left dorsolateral prefrontal cortex, which plays an important role in short-term or working memory and is abnormal in schizophrenia patients. Interestingly, parents, siblings, and children of people with schizophrenia show some of the same abnormalities to a lesser degree.
The researchers recruited 11 participants: five adults with schizophrenia and six of their close relatives. Each participant received two 30-minute treatments — one using a negative electrical charge, which the researchers believed would be beneficial — and the other using a positive charge as a control.
During and after each treatment, participants were asked to complete a battery of cognitive tests. On tasks of verbal and visual working memory, participants performed significantly better after receiving a negative charge, and the effects were “surprisingly strong,” says Schretlen.
The research also tested participants’ verbal fluency, or word retrieval. People with schizophrenia often struggle to find the right words, Schretlen explains. Since the prefrontal cortex contains a brain region responsible for word retrieval, Schretlen thought transcranial direct current stimulation might help.
Schretlen gave participants a minute to list things they could buy in a supermarket. Most people taking the test rattle off items in categories, naming fruits, then vegetables, then dairy products, for example.
Schretlen found that while participants did not rattle off more words, they did better at the challenging task of switching between categories after a negative electrical charge.
The stimulation “was associated with better performance on working memory and subtle changes in word retrieval,” Schretlen said.
Schretlen is now studying transcranial direct current stimulation in a larger sample of patients using repeated sessions of stimulation, which he hopes will lead to lasting benefits.
“What’s nice about transcranial direct current stimulation is that it’s so benign. There are no bad side effects,” said Schretlen. “If it enables people with schizophrenia to think more clearly, it would make a huge contribution to the treatment of this devastating illness.”
Source: Johns Hopkins Medicine