• The technology described in this briefing is the Flow transcranial direct current stimulation (tDCS) headset and behavioural therapy app. It is used for treating depression.

  • The innovative aspects are that it targets the physical causes of depression and delivers medication-free treatment at home. A clinician monitors treatment and response through a remote monitoring portal.

  • The intended place in therapy would be as a first treatment for moderate to severe depression, or if the condition has not responded to other treatments.

  • The main points from the evidence summarised in this briefing are from 4 studies (1 multicentre, double-blind, superiority randomised controlled trial, 1 open-label, single-arm feasibility study, 1 acceptability study and 1 retrospective case series) including a total of 206 people. The studies show that Flow does improve symptoms of depression. There are also many published studies on tDCS systems other than Flow.

  • A key uncertainty around the evidence is that it is yet to be published in peer-reviewed papers.

  • Experts advised that Flow is an innovative technology, which would particularly benefit people whose symptoms have not improved with existing interventions or who have side effects with commonly prescribed medicines, such as antidepressants. They said that it can also be used as a first treatment. The clinical experts also said that Flow could be used at home rather than people needing to attend primary and secondary care appointments, which would further reduce the cost of treating depression.

  • The cost of the Flow headset is £399, which includes a 6‑week supply of electrode pads. There is also an option for rental, which is £79 per month including the headset and a month's supply of electrode pads. The Flow app is free.