One unusually well-designed study, he said, was from the University of Lyon in France, in which 30 people with schizophrenia reported that after TDCS, they heard voices about 30 percent less than before. The researchers followed up with the patients, and the treatment was still working, even after three months.
Frohlich decided that the schizophrenia study was so potentially life-changing for patients that it had to be replicated — and improved upon — as quickly as possible. According to the National Institutes of Health, about 1 percent of Americans have schizophrenia; many of them are too sick to work or even talk lucidly with their doctors about treatment. Antipsychotic medication helps some, but it has serious side effects. A 2013 study estimated that the costs of schizophrenia — from treatment to caregiving and unemployment — are about $4 billion a year in the U.S.