An increasingly popular device that's thought to improve cognition by delivering low-intensity electrical current to the front of the brain via electrodes could actually do more harm than good, according to a small, preliminary new study.

It's a new technology called trans-cranial direct current stimulation (tDCS) and it's advertised in the media and available online, and even the prestigious  John's Hopkins Medical School praises the technology online.

They describe it as "a non-invasive, painless brain stimulation treatment that uses direct electrical currents to stimulate specific parts of the brain," citing studies that concluded in the technology's favor, suggesting it could treat depression, anxiety, Parkinson's disease and chronic pain.

In the current study, psychologists from the Netherlands worked with 24 healthy participants, attaching tDCS electrodes to their foreheads as recommended for stimulating the cortex.

They used a commercial tDCS headset called "foc. us" that offers gamified and non-gamified stimulation and claims it can increase athletic endurance in addition to cognition.

Participants visited the laboratory two times and were each given -- unbeknownst to them -- both a real stimulation session and a placebo-like service.

During and after all stimulation sessions, the researchers asked their subjects to complete a working memory task.

Upon receiving active stimulation, participants demonstrated impaired memory performance, according to the study, which was published in the journal Experimental Brain Research.

"Even if preliminary, these results show the fundamental critical and active role of the scientific community in evaluating the sometimes far-reaching, sweeping claims from the brain training industry with regard to the impact of their products on cognitive performance," says study co-author Lorenza Colzato.

Colzato's co-author, Laura Steenbergen, says they spotted potential risks and misuses of the technology and conducted the study to learn more about it, for little research exists.

In January, neuroscientist Jared Horvath of the University of Melbourne in Australia conducted a meta-analysis of studies examining tDCS and working memory and concluded that findings were too diverse and therefore inconclusive.