Neuromodulation is the artificial stimulation of the brain designed to alter its activity. Doctors have used the technique in clinical settings for decades to treat conditions such as depression, schizophrenia and tinnitus.
The brain's thoughts and feelings are governed by electrochemical signals passed between neurons. Externally applied electric currents and magnetic fields can encourage or suppress neural activity. Neurons that are repeatedly primed to fire (or fall silent) together become more likely to do so at other times, which can cause long-term cognitive changes.
Electroconvulsive therapy (ECT) lessens depression by inducing seizures in the brain, using large amounts of electrical current.
Repetitive transcranial magnetic stimulation (rTMS) 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 treatments have failed, but guidelines require it to be performed by trained professionals: the repetitive pulses can cause seizures if not administered correctly, and the machines are clunky and expensive.
Transcranial direct current stimulation (tDCS) passes a continuous electric current of 1–2 milliamps (less than 0.2% of that used in ECT) between electrodes placed on the head. Its simplicity and relative safety have made it a candidate for consumer devices. A study published in Nature Medicine in October 2024 used sham headsets as a placebo and found that, among 174 patients, those treated with tDCS for ten weeks reported a significant reduction in depression symptoms.
Vagus nerve stimulation targets the vagus nerve, which links the brain, heart and digestive tract. It is used to lower stress by regulating heart rate and breathing, reduce inflammation and potentially boost mood.
Several companies sell at-home neuromodulation devices: Flow Neuroscience (Sweden) makes a tDCS headset for depression; Nurosym (Britain) makes an earpiece for vagus nerve stimulation; and Neurode (Australia) is developing a tDCS headband for ADHD. Britain's NHS is piloting Flow's headset as part of a scheme to treat depression, though most randomised controlled trials of consumer devices have so far produced inconclusive results.
Most people need some of their problems to help take their mind off some of the others.