FLOW NEUROSCIENCE, a Swedish company, advertises its headset as a way to “stop suffering from depression [and] feel alive again”. Nurosym, a British firm, promises that its earpiece is capable of “improving health without surgery or drugs”. Neurode, an Australian startup, says they are developing a headband that can “improve focus, impulse control and memory” in people with attention deficit and hyperactivity disorder (ADHD).