Can at-home brain stimulators make you feel better?

Mint

2 days ago

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 it is developing a headband that can 'improve focus, impulse control and memory" in people with attention deficit and hyperactivity disorder (ADHD).
The makers of these wonder-products claim that they work via neuromodulation: artificial stimulation of the brain designed to alter its activity. Doctors have used similar techniques in clinical settings for decades to treat such conditions as depression, schizophrenia and tinnitus. Selling devices directly to consumers offers the promise of treatment in the comfort of one's own home.
The theory suggests they should do some good. People's thoughts and feelings are governed by the electrochemical signals passed between neurons in the brain, which means externally applied electric currents and magnetic fields can be used to encourage or suppress neural activity. Neurons that are repeatedly primed to fire (or fall silent) together should become more likely to do so at other times—which can, in principle, cause long-term cognitive changes. Electroconvulsive therapy (ECT), for example, lessens depression by inducing seizures in the brain.
Neuromodulation takes a gentler approach. The best-studied type is repetitive transcranial magnetic stimulation (rTMS), which involves a magnetic coil placed on the scalp that is turned on and off. Several randomised controlled trials have shown that rTMS can alleviate clinical depression when other forms of treatment have failed. But guidelines require the procedure to be performed by trained professionals: the repetitive pulses can cause seizures if not administered correctly, and the machines are clunky and expensive.
Other techniques are gentler still. Transcranial direct current stimulation (tDCS)—the method used in both Flow Neuroscience's and Neurode's devices—passes a continuous electric current between electrodes placed on the head. The amount of electrical current used is very small: 1-2 milliamps, less than 0.2% of that used in ECT. That, combined with the fact that there is no need to keep switching equipment on and off, makes tDCS a simple and safer approach to neuromodulation.
Nurosym's device is equally user-friendly, making use of a similar device to stimulate the vagus nerve—which links the brain, heart and digestive tract—to lower stress (by regulating heart rate and breathing), reduce inflammation and potentially boost mood.
The potential of such at-home devices could be enormous. Britain's National Health Service is already offering access to Flow's headset as part of a pilot scheme to treat depression. But most randomised controlled trials thus far have produced inconclusive results.
That may change. One long-standing difficulty in collecting good data has been finding an effective placebo to compare with an operating neuromodulation device. A study published in Nature Medicine in October reported on an experiment that overcame this hurdle by using sham headsets that felt like the real thing. Its authors found that, among 174 patients, those treated with tDCS for ten weeks reported a significant reduction in depression symptoms. Other studies may follow its lead.
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