Transcranial Magnetic Stimulation (TMS) for Depression, OCD: What to Know

It isn’t a part of the brain most people know about, but the dorsolateral prefrontal cortex is an important region linked to the state of rumination (or dwelling on negative feelings and thoughts)—a common symptom of depression, which affects an estimated 8.3% of adults in the United States.

This area of the brain, therefore, is one medical researchers are targeting for the treatment of certain mental health conditions, including depression and obsessive-compulsive disorder (OCD). A noninvasive procedure called transcranial magnetic stimulation (TMS) has become more popular in recent years as a treatment for these and other mental health conditions.

With TMS, the dorsolateral prefrontal cortex is stimulated by magnetic pulses. Patients wear a cap fitted with a magnetic coil for a series of treatments that last from 3 to 30 minutes. The pulses induce small electric currents that reset dysfunctional brain patterns associated with depression, essentially regulating mood and bringing relief.

TMS may sound like electroconvulsive therapy (ECT), a brain-stimulating treatment that is also used to effectively treat depression, but it differs in several ways. ECT requires general anesthesia and sends electrical currents into various parts of the brain to initiate a seizure to cause changes that reverse depressive symptoms. TMS does not require anesthesia and does not induce a seizure as a way to deliver treatment. However, the idea of targeting certain areas of the brain with an outpatient procedure (rather than medication) and bringing about chemical changes that can mitigate symptoms of depression is the same.

TMS was developed in 1985 by researchers in England. The Food and Drug Administration (FDA) approved it for the treatment of major depression in 2008. Since then, it has been approved for OCD, a mental health condition that causes excessive or intrusive thoughts and repetitive behaviors, certain types of migraines, and smoking cessation. Its use is also being studied for a variety of mental health and other conditions, including anxiety, post-traumatic stress disorder (PTSD), Parkinson’s disease, multiple sclerosis, autism, and Alzheimer’s disease.

We sat down with Sherab Tsheringla, MD, a Yale Medicine psychiatrist and TMS researcher, to talk more about TMS for the treatment of depression and OCD, which is offered through Yale New Haven Psychiatric Hospital’s Interventional Psychiatry Service (IPS). IPS provides procedure-based treatments to patients who have not been helped by commonly used medications and other techniques.

TMS uses an electromagnetic coil as a noninvasive device to target underlying brain regions. Noninvasive means there is no need for any surgery or even breaking the overlying skin to reach the brain.

During a treatment session, the TMS coil, which is connected to the TMS machine, is placed by the treating team on top of a specific part of your scalp. The TMS machine passes a current through the insulated TMS coil, which then generates magnetic pulses that penetrate into underlying brain structures, stimulating small electrical currents in your neurons.

While we do not know the exact mechanism by which TMS acts in the brain, we know from neuroscience research that there are changes to specific brain regions after TMS, and those changes are helpful in treatment-resistant depression—a type of depression that has not responded to treatment with multiple antidepressant medications—and as an adjunct treatment for OCD.

Before we start TMS, we first find your "motor threshold," which we combine with our first treatment session. During that visit, you meet the psychiatrist, who will do the threshold mapping and oversee treatments. We answer any questions you may have, and then you would sit in a comfortable reclining chair.

Then, we have you put on a cap on which we mark specific locations on your scalp using standardized measurements. We proceed with finding your “motor hotspot,” which translates to finding the part of your brain that controls the movement of your thumb. We send a magnetic pulse to that brain area and see your thumb twitch. Following this, we determine the minimum dose needed to elicit that response. This is your motor threshold.

We also use your motor hotspot to estimate the location of the dorsolateral prefrontal cortex. While its general location is the same for everyone, there can be some individual variability due to differences in the size and shape of the brain.

The motor threshold procedure takes 10 to 45 minutes, and we may need to repeat it later over weeks of treatment for some individuals. Because there are different protocols for TMS that vary in the individual stimulation parameters we set on the machine, the actual treatment, depending on the protocol we use, can range from around 3 to 30 minutes.

For OCD, the treatment includes incorporating “stimulation provocation,” and, on average, treatments last from 18 to 30 minutes. In this protocol, your treating psychiatrist will review your OCD symptoms and collaborate with you on generating a list of stimuli that provoke your OCD symptoms prior to starting treatment. We then use these provocations to activate a specific brain region just as TMS is administered there.

To help patients understand what TMS is like, we often have them first feel a pulse from the magnetic coil in their hand so they can experience the sensation.

When the coil is on the scalp, the stimulation feels like a light-to-moderate intensity tapping on your head. These usually come as fast bursts of pulses, followed by a gap, or pause. The 3-minute protocol that we often use for depression is called the intermittent theta burst protocol. For some individuals, we also use something called a high- or low-frequency repetitive TMS protocol, which involves a more continuous tapping and lasts about a half-hour.

Typically, treatments are five days a week, Monday through Friday, for six weeks. Most insurance companies cover that basic series of 30 treatment sessions for the treatment of depression. We also offer continued “preservation TMS” sessions that taper off to fewer visits per week after completion of the initial course, depending on clinical need—this would also depend on continued insurance coverage for extending treatments.

There's a real hope that TMS treatments are durable, which means that, once you respond well to them, you can stay in remission, or experience a significant reduction in symptoms, for a significant period of time.

TMS is an effective intervention for treatment-resistant depression and OCD. About 60% of people who didn’t respond to other depression treatments respond to standard TMS protocols, and more than half of these patients stay in remission at six-month follow-up appointments after stopping TMS.

In order to keep our patients in remission, we encourage them to keep up with the rest of their psychiatric management. For example, if they are in therapy or on medication, we encourage them to consult with their psychiatrist to determine if they should continue these treatments or change them.

TMS is as safe as having an MRI [magnetic resonance imaging], and it does not involve radiation.

Because the TMS coil is placed on your scalp, there can be discomfort and pain in that area. People can also develop headaches or migraines, which usually go away by the next day. That’s because the magnetic pulses stimulate neurons in the brain, which can alter normal brain activity. This stimulation can affect the blood flow and neurotransmitter levels, potentially triggering headaches or migraines in some individuals.

Others may have some discomfort in other parts of their body during the treatments—for example, around the eyes or with their jaw because the magnetic fields used in the treatment can stimulate nerves and muscles near the treatment area. This stimulation can lead to muscle contractions or twitching, which might be mildly painful for some people.

Another potential side effect involves hearing loss because the process of generating the magnetic pulses used during the treatment creates an acoustic feedback or a loud “clicking” sound. Tinnitus, a condition characterized by the perception of noise or ringing in the ears when no external sound is present, can also occur after TMS. However, these risks are minimized with the short duration of exposure to these sounds and the use of ear plugs.

Syncope, or fainting, is a known side effect related to TMS, which can also occur because of psychological factors, such as anxiety around procedure, and physiological factors, such as inadequate hydration. Your treating team will work with you to feel relaxed and comfortable prior to the procedure. Making sure you’re adequately hydrated and in good physical health will also help in having an uneventful treatment session.

And finally, there is a very low risk of seizures—about 0.1%. This is more likely in people who have underlying risk factors that were not addressed, a history of a seizure disorder, or being on medications, such as tricyclic antidepressants or certain neuroleptic medications that make you more likely to have seizures.

At IPS, we offer TMS to anyone ages 18 and older with treatment-resistant depression or OCD. So, if you are depressed or you have OCD and other treatments haven’t been helpful, our team is available for consultation. We require a referral from your psychiatrist or mental health prescriber.

We also offer consultation for adolescents. With evolving FDA guidance on TMS use in adolescents and our own research at Yale into adolescent depression, we would encourage parents to reach out to us with further questions.

The contraindications to TMS are like those for getting an MRI, which is having anything in your head or scalp that could heat up, move, or be disrupted by TMS, which includes metal objects, surgical clips, or shrapnel, and also devices like deep brain stimulators, cochlear implants, or implanted pacemakers. Patients with a history of head injury, seizure disorder, or substance use disorder may be at higher risk for side effects such as seizures with TMS and will need careful review before considering TMS.

The initial and subsequent motor threshold procedures are done by an IPS physician. The day-to-day treatments are done by TMS-trained technicians. They train on the specific device we use, and they're also trained in psychiatric symptom monitoring. They perform rating scales at scheduled intervals with the patient to see how their depression or OCD symptoms are doing. The physician will check in with the patient at least once a week and throughout the course of treatment.

By virtue of being around for such a long time, ECT has a much larger body of evidence to support it. It is a very effective treatment for severe depression with suicidal ideation, psychotic depression, and catatonia, which presents with features such as mutism, decreased physical movements, or abnormal posturing. If someone has psychotic depression, we would not consider TMS but suggest ECT instead.

At this point, we don't yet have any clinical evidence based on head-to-head trials between TMS and ECT that can help us answer which is better for certain kinds of depression. But we discuss all options with our patients to see what they've tried and what they would like to try as we attempt to match, to some degree, the treatment modality to the severity of clinical presentation and clinical features of the patient.

One big difference between ECT and TMS, however, would be cognitive side effects. A common feature of ECT is having short-term memory loss, even though this is temporary and patients usually can expect recovery from those symptoms once the ECT has been stopped. But with TMS, there is no or very little concern for cognitive side effects.

One of the greatest advantages of TMS in the context of other psychiatric procedures, such as ECT, is that you drive yourself to and from the appointment, and, when finished, you are able to return to work.

TMS offers hope to individuals who have not felt like they had any after trying several treatments that have not been effective. There is also an opportunity here, even from a neuroscience perspective, to better understand different parts of the brain, how they function, and how we can then modulate them to guide future treatment.

It’s always exciting in a field where medicines have remained stagnant for such a long time to develop interventions such TMS. The future looks really promising.