In the U.S. alone, roughly 20 million people suffer from depression. Far too many of them don't have access to proper mental health treatment.

Would it surprise you to know there's an app for that? In fact, there are hundreds of apps aimed at helping people deal with depression and anxiety, and they're being hailed by some mental health professionals as a way to spread otherwise-unavailable treatment to those in need. "There are a lot of problems with reaching people in rural and poor areas," says Tchiki Davis, a PhD student studying psychology at the University of California, Berkeley. "Apps are a great way to reach people who aren't currently getting services."

Some "depression" apps are good, or at least mostly benign, offering guided meditation, tips for stress relief, and even uplifting daily quotes. But others dubiously claim to evaluate symptoms or provide advice on various depression medications. And as more of these tools flood the market, a question looms: Do they actually work? After all, it doesn't take a degree in psychology or psychiatry to build and market a mobile app.

"There are so many — we're talking hundreds and hundreds of apps — that don't have any research, support, or evidence," says Kathryn Noth, a clinical psychologist with the Center for Behavioral Intervention Technologies at Northwestern University. The FDA has caught wind of this, and in February announced plans to regulate apps that "MAY meet the definition of medical device." But that definition is a loose one and is bound to overlook many apps marketed as depression tools.

Meanwhile, researchers see an opportunity to create apps rooted in science, putting effective mobile therapy in the palms and pockets of the masses. Noth is part of a team at Northwestern testing a new tool called IntelliCare, a suite of 12 apps, each focusing on a different skill or strategy proven effective for treating depression or anxiety in a therapy setting. For example, the "Daily Feats" app lets users track their daily achievements, while the "Worry Not" app uses worry management techniques to reduce anxiety. The suite comes with a "hub" app that sends users encouragement and recommends specific apps based on a user's symptoms and needs, just like a real therapist.

"These apps were developed by clinical psychologists using the same strategies that we know have research support in face-to-face therapy," Noth says.

But can an app do the nuanced work of a therapist? Jay Lebow, a clinical psychologist from The Family Institute at Northwestern University, is wary. "They're not a replacement for a mental health provider," he says. "Psychotherapy is about forming a relationship with somebody and in that context using that relationship as the base for setting goals."

Davis is skeptical of the argument that in-person therapy is the gold standard for treatment. "There are a lot of types of therapy that don't work at all," she says. "Our culture kind of thinks a one-on-one interaction where we talk about ourselves is something that's supposed to help us when that's not always true. There are all these skill-building techniques that are helpful that can be done online." She's trying to create mobile tools that make therapy fun, not a chore, because one of the biggest problems in mental health is motivating people to actually get help. "If you could figure out a way to help people help themselves where they don't deliberately have to walk down the self-help aisle or call up a therapist and go to their office, then I think the whole motivation problem will be improved a lot."

Could these apps deter people who really need face-to-face therapy from seeking it out? Noth says the goal of tools like IntelliCare is to bridge that gap, not widen it, giving people an introduction to treatment. If they need more than what the app has to offer, they'll already have a foot in the world of therapy.

"I definitely think these things will be integrated into therapy more and more, and that's a good thing," she says. "I don't think this will in any way take the place of therapy. I think it's an adjunct, an add-on, that will increase access to people who wouldn't be able to walk through my door."