The idea sounds outlandish at first: strap on a headset, run a faint electrical current through your skull, and feel your depression lift. Yet that’s exactly what Flow Neuroscience has built and, according to its data, it works.

Founded by two psychiatrists who grew frustrated by the limits of antidepressants, Flow began as an academic experiment and evolved into a consumer medical device used by tens of thousands of people. Its claim is pretty radical: that mental illness can be treated not with drugs but with targeted electricity. More than 80% of Flow users, the company says, experience remission from their symptoms within three weeks.

It’s an intervention that is badly needed. In England alone, over eight million people are prescribed antidepressants each year. Many report modest relief alongside a range of side effects including insomnia, fatigue and emotional blunting. Flow’s pitch is this: what if we could correct the brain’s circuitry directly, instead of medicating its chemistry?

Erin Lee, the company’s CEO, insists it isn’t fringe science. The headset uses transcranial Direct Current Stimulation (tDCS), a form of mild neuromodulation long used in clinical settings. The current targets the brain’s left dorsolateral prefrontal cortex, an area that shows reduced activity in people with depression. “We nudge those neurons back to activity,” she explains. “We’re increasing activity in a low-activity region and that reduces depressive symptoms.”

There are, of course, hurdles to negotiate. Healthcare providers tend to start with a demand: prove it. Flow’s answer is the data, including a Nature Medicine trial showing remission rates three times higher than placebo. As Lee, who we spoke to at the recent HLTH Europe conference in Amsterdam, puts it; the ambition is simple but sweeping; to raise the baseline of what patients should expect from treatment. No side effects. Greater effectiveness. And a choice beyond a pill.

For someone who’s not familiar with Flow, how do you describe it?

Flow is a wearable treatment for depression that uses mild electrical stimulation to treat the root cause of the disease.

And what might the outcome be from using it?

Over 80% of our users see full remission from their symptoms in about three weeks.

How has the product been developed? Where did it start and where are you now?

Our co-founders were actually psychiatrists by training. What they saw were the limitations of drugs for many patients who were struggling with depression. So it really came from an undergraduate research project, an evaluation of this technology, which has actually been around for a while, and then a desire to build something that was really accessible and affordable, and safe enough for home use.

Has the effectiveness of the product increased over time, or did it work from the start?

What we’re finding is that we’re getting smarter about dosage – how frequently someone should use the technology and for how long they should use it. We’re also getting a lot better at identifying the right users. But as a teaser, we do have a second-generation device coming out, and we’ve come a long way in overall effectiveness and response rates.

Is it only for people with clinical depression? Can anyone try it?

Our first device was really focused on depression, and that’s where our clinical trials sit. But over time, after looking at the results from 40,000 real-world users, we do have a subset of users who are not clinically depressed that see benefits in sleep, mood, concentration and focus. So I think you will see expansion into that area.

So it’s not just for people with low mood. Even if you’re feeling great, you could still try it?

That’s right.

How exactly does it work?

When we look at depressed brains, what you’ll see is that in an area called the left dorsolateral prefrontal cortex, you often see lower activity in that region. We use a very mild electrical current to target that region and nudge those neurons back to activity. So we’re increasing activity in a low-activity region, and that reduces depressive symptoms.

What has the reaction been from healthcare providers? How easy is it to get in front of them, and how receptive are they to what you do?

What was surprising to us is that healthcare providers understand the limitations of drugs. They do work for about 30% of people, but that leaves 70% who don’t respond. What they’ve lacked is something that’s accessible and affordable as an alternative.

So I think what we first hear is, “Show me the science. Prove to me that this isn’t woo woo.” And then when they see the results, both in our trials and in the real world from their own patients, the device kind of speaks for itself. They’ve been far more open-minded than we anticipated.

How effective do you think antidepressant drugs are in making a positive impact on the lives of people taking them?

Almost certainly, for some users, they’re life-saving and we certainly don’t want to undermine that. But I think what we can admit is that they’re ineffective for many people who use them, and many more have pretty terrible side effects. So we’re saying: can we raise the baseline on what people should expect from a treatment? No side effects and a greater level of effectiveness.

Ultimately, this comes down to choice. If drugs work for you, great. But for those they don’t work for, they deserve an alternative.

What’s the current percentage split between people using drugs as an antidepressant solution versus people using devices like yours?

Drugs have dominated the market. But I think our early users, probably not a surprise, come to us because everything else has failed, whether that’s drugs, hospitalisations, or TMS. What we’re now seeing is an expansion of people who add this to an existing antidepressant.

Over time, I think we’re getting to a place where people are saying, “Why would we wait for everything to fail? Why don’t we start here?” So I think in the next few years, you’ll see this become a frontline treatment for depression.

If we had this conversation again in a few years, what might the depression treatment or mental well-being landscape look like from the user’s point of view?

I think it’s going to be unrecognisable. We’ll look back on this period and see how immature it was. Today, treatments are really one-size-fits-all. If they don’t work for you, you’re called treatment-resistant, rather than us talking about the limitations of drugs.

I think we’re going to see highly personalised treatments. That’ll include everything from wearables for at-home, highly personalised stimulation, to implants, which we’re already seeing. So I really do think you’ll see a massive ecosystem here, and we hope to be a big part of that.

And your roadmap, how do you want the product to develop from here? Are there things you’re working on that you can share?

Our first device was really focused on highly accessible, affordable treatment, so it’s one-size-fits-all. Our second device introduces a diagnostic capability. We’ve gotten very good at identifying who might respond to our existing treatment and at personalising stimulation.

For users, we’re going to match that stimulation to your brainwaves for a more effective treatment for those who already respond, and to help people who didn’t respond to the first treatment respond to a personalised protocol. We’re really excited about that and hope to have it in the market very soon.

Erin Lee was speaking at HLTH Europe. Visit Flow Neuroscience.