McLean Hospital's HabitWorks app targets 'interpretation bias' in anxiety and depression with five-minute daily exercises

Someone tells you your fly is unzipped. Is that humiliating, common, or something to be thankful for? Pick one, score points, and move on to the next of fifty scenarios. The whole round takes about five minutes. That is the basic mechanic of HabitWorks, a smartphone app developed at McLean Hospital in Belmont, part of Mass General Brigham, and the subject of a clinical trial whose results were published Thursday.

The app is aimed at what psychologists call interpretation bias: the habit of leaping to the worst conclusion about an ambiguous situation. A headache becomes a brain tumor. A friend's delayed text becomes rejection. Over time, the researchers say, such thoughts feed anxiety and depression and can shape mood, behavior, and overall health.

HabitWorks tries to work on that habit directly. It offers weekly mood check-ins, short mental exercises, and a habit diary for tracking symptoms. The exercises present brief, personalized scenarios, and the more positive the interpretation a user chooses, the more points they earn. Dr. Courtney Beard, the study's senior author and director of McLean's Cognition and Affect Research Education (CARE) Laboratory, said the goal is to make people aware of other possible interpretations so they are less anxious and worried all the time. Alexandra Silverman, the lead author and a McLean psychologist, described it as a skill distinct from mindfulness apps, aimed at moments like a boss saying, "meet me in my office in 10 minutes."

It is not meant for a crisis. Beard said some apps are built to change how you feel in the moment, while this one is designed to reshape underlying thinking habits, and that people reflect better when they are not overwhelmed. Users are meant to set aside a scheduled time for it, like a practice session.

The trial enrolled 340 adults across 44 states last year. Participants were randomly assigned either to use HabitWorks for four weeks or to a control group that completed self-assessment surveys tracking anxiety and depression symptoms. Both groups answered self-report questionnaires afterward. The app users showed greater improvements in overall symptom severity and daily functioning, according to the study.

Retention was a notable result, since many mental health apps lose users quickly after download. At week four, 77 percent of HabitWorks users were still active, and 84 percent completed the final assessment. Lauren S. Hallion, a psychology professor at the University of Regina in Canada who was not involved, said treatments only work if people use them, and that consistent use without payment suggests the team met that goal. Because the participants covered a range of symptom severity, she added, the app may suit people who are generally doing well but want an extra boost. She also noted this is not the first smartphone study, nor the first to look at modifying interpretation bias, but that the technology keeps improving.

The researchers framed the app against a strained care system, with long waits for appointments and many providers not accepting insurance. Beard said the aim is to complement therapy and physicians, not replace them: "There will never be enough providers for those who need treatment." The app uses no artificial intelligence, and an advisory board including people with lived experience of anxiety and depression helped shape it. A $700,000 multi-year grant from the National Institute of Mental Health funded the work.

The evaluation is still early. HabitWorks is not publicly available and has a waitlist, and Beard hopes for a release before the end of the year. The team is still seeking sustainable funding and expects a pay-to-use model. Beard said she still wants to know who it works best for, in what situations, and why, but that it is ready for release once funding and maintenance are secured.