Direct Current Stimulation Boosts Cognition in Schizophrenia

Transcranial direct current stimulation (tDCS) may improve short-term memory in people with schizophrenia, a small study suggests.

Cognitive impairment is nearly ubiquitous in patients with schizophrenia, and effective ways to address it are lacking. "If tDCS could remediate the neurocognitive dysfunction that afflicts most patients with schizophrenia, it could prove to be an enormously important adjunctive treatment for the disease," David J. Schretlen, PhD, with the Departments of Psychiatry and Behavioral Sciences and Radiology and Radiological Science at Johns Hopkins University, in Baltimore, Maryland, told Medscape Medical News.

He noted that tDCS has "no known side effects other than some mild discomfort (itching, tingling, or burning sensations) at the site of the scalp electrodes. And I do mean 'mild.' I've worn a tDCS device many times, and it's barely detectable. In fact, many people can't feel it at all."

The study was published online in Clinical Schizophrenia and Related Psychoses.

Enhanced Cognition

Because tDCS has been shown to enhance cognitive functioning in healthy adults, Dr Schretlen and colleagues explored its value and tolerability in patients with schizophrenia. The study included 11 participants - five adults meeting DSM-IV criteria for schizophrenia, and six first-degree relatives who were free of schizophrenia or other Axis I mental disorders. First-degree relatives of patients with schizophrenia often show some of the same cognitive problems as their relatives with schizophrenia, albeit to a lesser degree.

Each participant completed tasks thought to be mediated by the prefrontal cortex during two 30-minute tDCS treatment sessions. In these sessions, the participants were provided with a constant current of 1.5 mA that targeted the left and right dorsolateral prefrontal cortex (DLPFC).

All participants tolerated tDCS well, the researchers report. They further observed that anodal stimulation over the left DLPFC improved performance relative to cathodal (control) stimulation on measures of working memory and aspects of verbal fluency relevant to word retrieval. The effects were "surprisingly strong," Dr Schretlen said. The effects of tDCS were "slightly stronger" in the first-degree relatives.

"Our findings are consistent with other studies showing that tDCS applied over the left dorsolateral prefrontal cortex can enhance working memory in other populations," said Dr Schretlen.

Durable Effect?

Reached for comment on the study, Georgios Petrides, MD, with the Division of Psychiatry Research, the Zucker Hillside Hospital, which is part of the North Shore–LIJ Health System, Glen Oaks, New York, said that the study results are promising but that the challenge is to determine whether the effects last. "," he noted.