It was invented in Sheffield the 1980s and has been used to treat a number of mental and physical health conditions, including OCD, anorexia, tinnitus and fibromyalgia — but studies suggest up to 70% of people with clinical depression could benefit from it.
Treatments usually centre around talking therapies, such as cognitive behavioural therapy (CBT) and antidepressant medicines.
For severe depression that hasn’t improved with other treatments, electroconvulsive therapy (ECT), where an electric current is applied to the brain under general anaesthetic, is sometimes used.
“TMS is a much more acceptable intermediary treatment between medication and ECT,” says consultant psychiatrist Dr Leigh Neal, medical director of the Smart TMS clinic in London.
“It involves a sea change of how we’ll treat people in the future and the outcomes for depression.”
TMS simply involves a magnetic head, which converts electricity into a magnetic field, being placed against the scalp.
The magnetic field sets up electrical circuits in the brain, affecting only a tiny area.
The region of the brain targeted depends on the condition being treated — for depression, it’s the left dorsolateral prefrontal cortex (DLPFC), where there’s reduced activity in people with the condition.
“Scans find that the beneficial effects of TMS propagate through to the deeper areas, so all the depression circuit is beneficially affected,” says Dr Neal, who explains the electrical stimulation causes changes within the brain related to chemicals and neuroplasticity (the ability of neurons to connect to each other).
“It causes more connectivity between nerves in the brain, an increase in the amount of neural activity, and an increase in the amount of neurotransmitters like serotonin.”
One treatment lasts about 40 minutes, and is given daily for between 10 and 30 sessions.
TMS is not considered a treatment for temporary low mood, however; rather clinical depression diagnosed by a GP or psychiatrist, and mainly for people who’ve had at least two courses of antidepressants
Any effect of TMS on depression is gradual, and there are some people for whom it doesn’t work at all.
However, trials show a recovery or remission rate after TMS of 30-40%, and another 30% get a substantial reduction in symptoms.
A review of 40 randomised controlled trials, including 1,592 patients with depression treated by repetitive TMS or sham stimulation, showed a significant effect in favour of TMS.
Patient responses were positive, describing significant benefits to their quality of life.
Dr Neal notes that people become more positive and sociable after a course of TMS: “You’re not just seeing a reduction in mood, you’re seeing people brighten up and become more energised — a qualitative difference you don’t see with antidepressants.”