What Is TMS Treatment? A Psychiatrist’s Guide

What is TMS therapy?

Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation treatment. A magnetic coil placed against the scalp produces brief pulses that induce small electrical currents in the outer regions of the brain. Repeated TMS, often called rTMS, aims to influence brain networks involved in mood and other psychiatric symptoms.

TMS does not involve surgery, an implanted device or a general anaesthetic. Patients remain awake during treatment and can usually resume ordinary activities afterward. It is most strongly established for major depressive disorder, especially when standard treatments have not provided enough improvement.

How does TMS work?

Depression involves distributed brain networks rather than one isolated “depression centre.” TMS is commonly directed toward areas of the prefrontal cortex that connect with networks involved in emotion, motivation and cognitive control. Its effects may extend through these connections beyond the area directly beneath the coil.

The precise antidepressant mechanism remains under study. Evidence suggests that repeated stimulation can alter cortical excitability, network connectivity and synaptic plasticity—the brain’s capacity to change how nerve cells communicate.

TMS differs from antidepressant medication, which acts through chemical receptors and signalling systems throughout the body. Psychotherapy works through learning, behaviour, relationships and emotional processing. These approaches are not necessarily competitors: depending on the person, TMS may be used alongside medication and psychotherapy.

Why is TMS used for depression?

The largest evidence base is for major depressive disorder. TMS may be considered when antidepressant medication or psychotherapy has not helped enough, when medication has caused difficult side effects, or when a psychiatrist determines that brain stimulation is an appropriate option.

“Treatment-resistant depression” generally describes depression that has not improved adequately after appropriate treatment attempts. Definitions vary, so the label should not be applied without clinical assessment. Our guide to treatment-resistant depression explains this topic in more detail.

Specific TMS approaches have also been studied for conditions such as obsessive-compulsive disorder (OCD). Targets and procedures can differ by condition, and evidence from one protocol should not automatically be applied to another.

What happens during TMS treatment?

Treatment begins with a psychiatric assessment. The clinician reviews symptoms, previous treatments, medications, substance use, neurological and medical history, and factors that could affect safety. Metal or electronic implants in or near the head require careful screening.

Before treatment, the team determines the motor threshold—the minimum stimulation needed to produce a small movement in a hand muscle. This helps personalize stimulation intensity. Head measurements or another targeting method are then used to position the coil over the intended brain region.

During a session, the patient sits in a supported chair while the coil rests against the scalp. The machine makes clicking sounds, so hearing protection is used. Pulses may feel like tapping against the scalp and can briefly contract nearby scalp or facial muscles. The patient stays awake and is monitored throughout.

• A course commonly involves sessions on multiple weekdays over several weeks.
• Session length ranges from a few minutes to roughly half an hour, depending on the protocol.
• Symptoms and tolerability are monitored during the course and at follow-up.
• Some people who benefit may later discuss repeat, rescue or maintenance TMS, but the best approach varies and remains an area of research.

Are there different types of TMS?

Yes. Protocols differ in stimulation frequency, pulse pattern, brain target, intensity and schedule. Common approaches include high-frequency stimulation, low-frequency stimulation and patterned treatment such as intermittent theta-burst stimulation (iTBS). Some protocols stimulate one side of the prefrontal cortex, while others use sequential bilateral stimulation.

These approaches do not all have identical evidence or suit every patient. For example, a large randomized trial found a brief iTBS protocol non-inferior to a longer high-frequency protocol for treatment-resistant depression, but that result does not mean every shortened or accelerated schedule is equivalent. Protocol selection requires clinical judgement.

How effective is TMS for depression?

Randomized sham-controlled trials and meta-analyses support TMS as an effective treatment for major depressive disorder, including treatment-resistant depression. The evidence is strongest for well-studied prefrontal protocols delivered repeatedly over a course of treatment.

Results vary with the population, protocol, number of sessions and degree of prior treatment resistance. Large naturalistic studies suggest that approximately 60% with treatment-resistant depression may achieve a clinically meaningful response, while remission accounts for about 30%. Real-world registries and controlled trials answer different questions, however, and individual benefit cannot be predicted from an average.

Some people improve gradually or later in the course, while others do not benefit. A psychiatric assessment can place the evidence in the context of a person’s diagnosis, previous treatments, health history and goals.

TMS side effects and safety

TMS is generally well tolerated when delivered according to established safety procedures. The most common side effects are temporary discomfort at the stimulation site, scalp or facial muscle twitching, and headache. These effects often lessen as the patient becomes accustomed to treatment, and adjustments may improve comfort.

Seizure is the principal serious risk, but it is rare when treatment follows safety guidelines. Risk can be affected by the protocol and by individual factors such as certain medical conditions, medications, substance use, withdrawal or severe sleep deprivation. Screening and reporting health or medication changes are therefore essential.

• Temporary light-headedness or dizziness can occur.
• The clicking sound can affect hearing without appropriate protection; earplugs or headphones are used.
• Mood elevation or hypomania/mania is uncommon but requires prompt clinical review.
• Some metal or electronic implants may make treatment unsuitable or require additional assessment.

Does TMS cause memory loss? How is it different from ECT?

Available evidence does not suggest that standard depression-focused TMS causes the characteristic memory difficulties that can occur with electroconvulsive therapy (ECT). TMS does not intentionally cause a seizure and ordinarily requires no anaesthesia.

ECT uses a controlled electrical stimulus under anaesthesia to produce a therapeutic seizure. It has an important role, particularly for some severe, urgent or psychotic depressions. TMS and ECT differ in procedure, evidence, speed of response and potential adverse effects; the appropriate choice depends on clinical circumstances.

Who may be a candidate for TMS?

TMS may be considered for an adult with major depressive disorder whose symptoms remain significant despite appropriate treatment attempts, or who has been unable to tolerate standard treatments. Diagnosis alone does not establish suitability.

Assessment is particularly important where there is a history of seizures, bipolar disorder or possible mania, neurological illness, substance withdrawal, pregnancy, or implanted metal or electronic devices. This article provides general education and cannot determine whether TMS is appropriate for an individual.

NeuroLinks provides psychiatrist-led TMS care in Nanaimo for appropriately selected patients from Vancouver Island and elsewhere in British Columbia. To discuss assessment or referral options, contact NeuroLinks without sending confidential clinical details through general website forms.