A few years ago while working on my undergrad I helped proctor a study involving a similar technology--transcranial direct current stimulation (tDCS)--and it's impact on working memory. Although neither the tech nor the desired outcome in OP's article is identical to my undergrad project, the researchers are likely facing similar challenges which seem universal for low-current brain stimulation experiments:

- Effects are measurable but very very small

- Frequent stimulation is required to achieve the desired effect

- The desired effect diminishes over time

This seems really promising, particularly because they're changing the treatment for specific patients rather than using a one-size-fits-all model. I hope their trials go well.