Overview

Transcranial magnetic stimulation (TMS) is a type of brain stimulation which consists of placing a magnet on the scalp and using electromagnetic pulses to target the activity of nerve cells in specific areas of your brain, with the hope of improving symptoms of psychological disorders. This is noninvasive, meaning that the procedure does not require surgery.¹ TMS has been approved as an effective treatment for depression, especially in patients who find medications and psychotherapies to be ineffective at alleviating their symptoms. With its success with depression, TMS is now being assessed for other psychological conditions, such as anxiety disorders. 

Anxiety disorders are a major group of mental health conditions characterised by uncontrollable feelings of worry and fear which significantly hinder a person’s quality of life, for instance affecting one’s social life, their sleep schedule and their cognitive function.² Due to the success surrounding TMS as a treatment for depression, it is believed that TMS would be effective for anxiety disorders as anxiety symptoms are also associated with depression, and are found to be alleviated when depression patients undergo TMS treatment.³ 

This article will explore how TMS works and its potential in treating anxiety disorder patients.  

How does TMS work?

You may be asking yourself how a magnet could affect how your brain works and the answer lies in the close relationship between electricity and magnetism. It is this relationship that TMS is based upon. 

When you bring a magnet close to something that conducts electricity, electricity will be generated. Your brain is known to be electrically active - your nerve cells generate small amounts of electricity to communicate with each other, to relay important information around your body, and to influence your emotions, including anxiety.⁴ By bringing a magnet close to your brain, the additional electricity generated can influence your nerves and your brain’s electrical activity.¹  

When someone is experiencing uncontrollable anxiety, different parts of the brain are affected. In the area immediately behind your forehead, known as the prefrontal cortex, anxiety can affect its nerves by decreasing their electrical activity.⁵ This alteration in turn affects another part of the brain which is connected to the prefrontal cortex, called the amygdala. 

The amygdala is the small but essential portion of your brain which processes your emotions, including anxiety. One of the roles of the prefrontal cortex is to inhibit electrical activity in the nerves of the amygdala, with the hope of suppressing unhealthy levels of fear and preoccupation.⁶ However, in people who suffer from heightened levels of anxiety, the decrease of electrical activity in the prefrontal cortex means that there is no suppression of nerve activity in the amygdala, in turn leading to a significant increase in electrical activity in this area of the brain. 

This hyperactivity in the amygdala is thought to play a role in the continuous, uncontrollable anxiety that patients feel.⁷ In order to “fix” the lack of electrical activity in the prefrontal cortex and the surplus electrical activity in the amygdala in anxiety disorder patients, TMS could be used. 

The TMS magnet could be placed over the prefrontal cortex, and the electricity generated could be used to stimulate nerve activity in this area of the brain. This would have an indirect effect on the amygdala and inhibit its nerve activity, in turn suppressing anxiety. Studies have found TMS to be effective for anxiety disorders, as patients in these studies are showing significantly decreased anxiety symptoms.⁸

Details of the TMS procedure

Patient selection criteria

Before undergoing TMS, a patient is referred to a specialist who is trained for this particular treatment. The patient will meet with this specialist in order to make sure they meet a specific criteria, to check there are no contraindications to receiving TMS.¹ 

A good candidate for TMS includes those who:

• Have not responded to pharmaceutical medications for anxiety
• Experience adverse side effects when taking pharmaceutical medications
• Are a child or a teenager - Since young people are more prone to developing negative side effects from medications, this noninvasive TMS treatment could be a better fit

People who do not fit the criteria for TMS treatment and are told to avoid it include those who have any metal implants in their heads. This is very important, as the TMS magnet could heat up or move the metal, which could result in serious injuries.⁹ 

Examples include people with:

• Aneurysm clips
• Cochlear implants
• Permanent piercings
• Stents found in the brain or neck
• Bullets or shrapnel
• Electrodes

People who have a history of seizures or epilepsy also do not fit the criteria for TMS. In addition, anyone who is taking stimulants also cannot undergo TMS. This is because this particular class of medication purposefully alters the activity of nerves found in the brain and spinal cord, and hence TMS could affect these desired changes.⁹

What does TMS treatment entail?

Once a patient is cleared for TMS, they can start the treatment process. TMS treatment takes place in an outpatient clinic, meaning the patient does not have to stay in hospital overnight. The treatment can also be done outside of the hospital, for example in a medical clinic.¹

As the procedure is noninvasive, the only thing a patient would need to do to prepare before the treatment is to remove any metal they may be wearing. TMS is done with no anaesthesia so the patient is awake throughout the whole treatment.¹ 

The patient will then be asked to sit in a specially designed chair placed underneath or next to the TMS magnet. They will then be given hearing protection, such as earplugs, to make sure their ears are not damaged by the loud sounds of the magnet. The magnet will then be positioned onto, in the case of anxiety disorder patients, their prefrontal cortex - either as a helmet with a chin-strap or positioned on the scalp using an extension arm.¹

During the first treatment session of TMS, the specialist must perform something called “the mapping process”. This consists of the magnet sending out single-pulse stimulations onto the scalp of the patient, which will feel like someone is tapping repeatedly on their head. This is done to find the right location of the prefrontal cortex, and to find the right dose of magnetic energy for the treatment, which is found when the patient’s hands or fingers start to twitch. The mapping process is only done once, with subsequent sessions using this same position on the patient’s head. Once this process is completed, the treatment can be delivered.¹ 

The most common type of TMS treatment that is being assessed for anxiety disorder patients is repetitive TMS (rTMS).⁸ This procedure consists of the TMS magnet delivering magnetic pulses to the prefrontal cortex with a specific timing and pattern. 

Similar to the mapping process, these magnetic pulses feel like someone is tapping on the scalp of these patients. They will also hear clicking sounds throughout the treatment, which signal when the magnet is turning on and off - this is done to make sure that the magnet is given time to cool, as continuous delivery of magnetic pulses could overheat the TMS magnet. 

The patient may feel some discomfort during the treatment, as the tapping magnetic pulses could cause some pain to the patient. Depending on the specific type of rTMS, the treatment session can last anywhere from a few minutes to half an hour.¹ 

After the treatment

The patient can leave straight away after treatment, continuing their daily activities with no problem if they feel no side effects. If a patient feels lingering discomfort from the tapping, then waiting a couple minutes should allow these sensations to wear off.¹

This type of treatment session is repeated 5 days a week, for roughly 4-6 weeks - the exact amount of time depending on the specific anxiety disorder. The goal is that at the end of this treatment plan, the magnetic stimulation will have influenced the patient’s prefrontal cortex and amygdala nerve cells, and in turn will have helped alleviate the patient’s anxiety symptoms.¹ 

Benefits and risks of TMS

The advantages of TMS include:

• Noninvasive - The fact that the procedure is noninvasive and does not require any type of surgery or anaesthesia greatly reduces the risk of developing any adverse side effects
• Generally well-tolerated and safe - Most research has shown that TMS can be considered a safe treatment, with most side effects which occur being mild and very short-term (lasting only minutes after the treatment). Any serious side effects that could occur are incredibly rare
• Cooperation with other treatments - The procedure can easily be done alongside other types of anxiety disorder treatments, such as talking therapies and pharmaceutical medications. This gives the patient an increased chance of recovering from their symptoms

However, as mentioned above, TMS can lead to negative side effects. Most of these do improve shortly after a treatment session, making them quite mild. Examples include: 

• Mild headaches - These tend to be the most common side effect
• Feeling lightheaded
• Pain in the scalp or the neck
• Facial twitching or tingling
• Feeling sleepy
• Altered cognition 

A more serious risk that could occur after TMS treatment is suffering from seizures. This side effect is particularly rare - there is only a 0.1% risk.¹⁰ 

Summary

Transcranial magnetic stimulation is a noninvasive brain stimulation therapy which uses magnetism to alter the activity of nerve cells in specific parts of the brain, in turn alleviating symptoms of depression and anxiety. This treatment has been approved for depression, and it is now being researched as a new procedure for anxiety disorders. Candidates for this type of therapy include those who have a low risk of suffering from seizures and those who do not feel any benefits after a course of medication. Studies so far have shown that repetitive TMS treatment on the prefrontal cortex of anxiety disorder patients is a safe and effective treatment, with the risk of experiencing any negative side effects being low. However, there are a limited number of studies on this matter, and no standard of TMS treatment procedure has been developed yet for anxiety disorders. Hence, more research is needed to assess how to make TMS as effective as possible as a direct treatment for anxiety.