Akili Interactive Labs, a Boston and San Francisco Bay Area company created by PureTech Health, said Monday that AKL-T01, an experimental video game it has been developing as a digital medicine for attention-deficit/hyperactivity disorder (ADHD), hit its main goal in a pivotal trial. Children and adolescents diagnosed with ADHD before starting the 348-patient study who utilized AKL-T01 for four weeks showed statistically significant improvement on a psychiatric test used to measure their attention and screen for ADHD, the company said. Patients in a control group who played another video game showed no improvement on the test, known as the Attention Performance Index. The study was the first of its kind.

There are a few outstanding questions, however. Akili only provided a snapshot of the data; it said it will present the full study details at a future medical meeting and submit them to a peer-reviewed journal in the future, so the magnitude of the benefit provided is unclear. In addition, AKL-T01 failed to separate from control on a range of secondary measures tracking behavioral changes. There were no serious side effects: 11 were reported in the study, mainly headache and frustration. One patient dropped out of the study, Akili said.

Nonetheless, Akili will seek FDA approval for AKL-T01 as treatment for children and adolescents with ADHD, which the American Psychiatric Association has estimated affects 5 percent of children. ADHD can be treated with behavioral therapy or medication, though medical treatments can come with side effects.

Akili’s news comes at a time when the very definition of a medical treatment has been evolving. Within the next few years, medicines using gene therapy, RNA interference, and a genetically modified, living cell therapy, could all be approved by the FDA. Digital medicines—in which electronics like smartphone apps serve as the therapy—are also starting to break through. In September, the FDA approved an app from Pear Therapeutics to treat substance abuse disorders.

That ruling was the first of its kind, and it helps set the stage for Akili, which has been conducting clinical trials of its software in patients with ADHD and other neurological diseases like Parkinson’s, major depressive disorder, Alzheimer’s disease, and traumatic brain injury. The idea behind the company’s products is that they might help better track the progression of each disease and potentially help treat it in its early stages. The technology, based on research at the University of California, San Francisco, helps measure how the brain responds in a goal-directed environment when multi-tasking. When tailored to ADHD, for instance, the product is supposed to help improve attention and working memory.

There is still so much to learn about the human brain, and that mystery sets up an interesting dynamic with Akili: even as the company accumulates more evidence that its software can have a positive effect on ADHD patients, its leaders can’t fully explain how or why.

The basic idea is that Akili’s software algorithms render sensory stimuli on the screen that are meant to “activate” specific neural networks, said president and CEO Eddie Martucci (pictured) in a phone interview. In the case of AKL-T01, the software tries to impact neurons in the front of the brain related to attention, impulse behavior, and cognitive control. “Instead of receptor-based pharmacology, we go right to the source—how the brain processes information,” he said, referencing ADHD drugs that act on brain chemicals.

Repeatedly activating these neurons might improve brain function in some patients. “But exactly how that happens, I would honestly say that’s still something we—and the world of neurology—are still figuring out,” Martucci said.

Four pharma companies—Merck, Shire, Amgen, and Pfizer—have each aligned with Akili either via investments or partnerships. Most recently, in 2016, Merck and Amgen backed a $42 million Series B round for the company. AKL-T01 could be its first product.

“We’re really excited,” Martucci said.

Akili plans to file for FDA approval sometime next year, Martucci said. He declined to share more details about the magnitude of the benefit patients experienced in the pivotal trial, or about what happened with the secondary measures of the study. The company plans to analyze the results more deeply in the coming weeks, with the goal of publishing more information in early 2018, he said.

Even though the trial didn’t hit all of its goals, Martucci is optimistic about the case Akili will make to the FDA. “Nothing in the trial jumped out and was concerning or a red mark in any way,” he said.

As AKL-T01 moves closer to the market, Martucci said other items on Akili’s agenda include determining the most effective “dosages” of the product and learning which types of ADHD patients it benefits the most.

Akili envisions patients using AKL-T01 over an extended period of time, although there is some early, limited evidence that the effects can be maintained in patients after they stop using the game regularly, Martucci said. “It’s a little too early to say we’ve validated that,” Martucci said. “We don’t hold some sort of promise to the marketplace like this will be a one-month cure.”

Akili plans to pitch AKL-T01 as an alternative to traditional ADHD medications. Its target patients include those whose parents don’t want to put their children on drug therapies, or those who haven’t had success with ADHD pharmaceuticals, Martucci said.

If AKL-T01 gets approved, patients would access it via a doctor’s prescription. It’s too early to talk about how much the product would cost, Martucci said.