Brain stimulation using gentle electricity may boost short-term memory in people with schizophrenia, suggests a new study.
The procedure is referred to as transcranial direct current stimulation, and it involves locating electrodes on the head and passing a weak electrical current between them. It is regarded as safe by researchers.
David Schretlen, professor of psychiatry and behavioral sciences at Johns Hopkins University, explains:
“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.”
Researchers focused on a brain area called the left dorsolateral prefrontal cortex. It plays an important role in short-term, or working memory, and is altered in those with schizophrenia.
Curiously, children, parents, siblings of people with schizophrenia show similar abnormalities, although to a lesser degree.
The study involved 11 participants, five adults diagnosed with schizophrenia, and six of their close relatives.
Each particpant received two 30-minute treatments. One treatment used a negative electrical charge, which the researchers thought might prove beneficial. The other treatment used a positive charge, as a control.
During and following each treatment, participants completed cognitive tests. On tests of verbal and visual working memory, participants performed significantly better after receiving a negative charge, and the effects were surprisingly strong, Schretlen said.
The study also investigated verbal fluency, or word retrieval. Those with schizophrenia often struggle to find the right words.
Since the prefrontal cortex contains a brain region responsible for word retrieval, researchers thought transcranial direct current stimulation might be of help.
To test the idea, participants were given a minute to list things they could buy in a supermarket. Most people taking the test rattle off items in categories, for example, naming types of fruits, then vegetables, then dairy products.
While the study participants did not come up with more words, they did better after a negatively charged treatment at the challenging task of switching between categories.
The stimulation was associated with better performance on working memory and subtle changes in word retrieval, Schretlen says:
“What’s nice about transcranial direct current stimulation is that it’s so benign. There are no bad side effects. If it enables people with schizophrenia to think more clearly, it would make a huge contribution to the treatment of this devastating illness.”
David J. Schretlen, Joseph J. van Steenburgh, Mark Varvaris, Tracy D. Vannorsdall, Megan A. Andrejczuk, and Barry Gordon
Can Transcranial Direct Current Stimulation Improve Cognitive Functioning in Adults with Schizophrenia?
Clinical Schizophrenia & Related Psychoses doi: http://dx.doi.org/10.3371/CSRP.SCST.103114