Transcranial direct-current stimulation

Transcranial direct current stimulation (tDCS) is a form of neuromodulation that uses constant, low direct current delivered via electrodes on the head. It was originally developed to help patients with brain injuries or neuropsychiatric conditions such as major depressive disorder. It can be contrasted with cranial electrotherapy stimulation, which generally uses alternating current the same way, as well as transcranial magnetic stimulation. Research shows increasing evidence for tDCS as a treatment for depression. There is mixed evidence about whether tDCS is useful for cognitive enhancement in healthy people. There is no strong evidence that tDCS is useful for memory deficits in Parkinson's disease and Alzheimer's disease, non-neuropathic pain, nor for improving arm or leg functioning and muscle strength in people recovering from a stroke. There is emerging supportive evidence for tDCS in the management of schizophrenia - especially for negative symptoms. In 2015, the British National Institute for Health and Care Excellence (NICE) found tDCS to be a safe and effective treatment modality for depression, though further investigation was needed. Since then, several studies and meta-analyses have demonstrated tDCS to be a safe and effective treatment for depression. A meta-analysis published in 2020 found moderate- to high-quality evidence for tDCS as a treatment for depression with only low to moderate clinical efficacy. Active tDCS was significantly superior to sham for response (30.9% vs. 18.9% respectively), remission (19.9% vs. 11.7%) and depression improvement. According to a 2016 meta analysis published in the British Journal of Psychiatry, 34% of tDCS-treated patients showed at least 50% symptom reduction (compared to 19% placebo) across 6 randomised controlled trials. Recent research on tDCS has shown promising results in treating other mental health conditions such as anxiety and PTSD. More research is required on the topic. There is also evidence that tDCS is useful in treating neuropathic pain after spinal cord injury.