Depression - rTMS
rTMS works by converting magnetic fields to generate electrical currents near the DLPFC region in the brain, thereby stimulating the DLPFC and increasing the neural activity in that area. It is hypothesized that patients with depression have lower DLPFC activity levels compared to others. By providing appropriate stimulation and restoring normal activity levels in this region, patients' depressive symptoms can be alleviated.
Treating Depression without Medication? Understanding the Mechanism of rTMS Therapy
For a long time, the formation and treatment of depression have been based on the monoamine hypothesis: a lack of serotonin and other neurotransmitters in the brain leads to depression, and by taking antidepressant medications, patients can replenish these substances and alleviate their depressive symptoms.
However, years of research have revealed that the development of depression may be influenced by other factors. Scientists have discovered that in the brains of individuals with depression, the activity levels in certain areas differ from those in healthy individuals.
For example, people with depression tend to have higher activity levels in the ventromedial prefrontal cortex (VMPFC), located in the inner part of the frontal lobe. In contrast, they generally have lower activity levels in the dorsolateral prefrontal cortex (DLPFC), located in the outer part of the frontal lobe, roughly where the hairline forms an "M" shape.
When their depressive symptoms improve, the activity levels in the VMPFC decrease, while those in the DLPFC increase. Researchers have also found that in some stroke patients, if the VMPFC is damaged, their depressive symptoms tend to become milder. Conversely, if the DLPFC is damaged, they tend to become more depressed.
rTMS therapy is based on this principle. rTMS works by converting magnetic fields to generate electrical currents near the DLPFC region in the brain, thereby stimulating the DLPFC and increasing the neural activity in that area. It is hypothesized that patients with depression have lower DLPFC activity levels compared to others. By providing appropriate stimulation and restoring normal activity levels in this region, patients' depressive symptoms can be alleviated.
The Drawbacks and Limitations of rTMS Therapy: Is It as Good as It Sounds?
As a treatment option for depression and even treatment-resistant depression, rTMS is undoubtedly good news for patients, providing them with an additional choice for therapy.
Some patients are reluctant to take medications and initially only have psychotherapy as an option. However, with rTMS, they now have another choice, treating depression through neuromodulation. While undergoing rTMS therapy, patients can choose whether or not to take medications. Compared to other treatment-resistant depression therapies like electroconvulsive therapy (ECT), rTMS does not require general anesthesia, and the risks and side effects patients face are relatively lower.
The side effects and limitations of rTMS
Despite its benefits, rTMS also has drawbacks and side effects. rTMS generates electrical currents in the brain by converting magnetic fields, but sometimes these currents can stimulate the trigeminal nerve near the scalp, causing headaches for the patient.
The continuous clicking sound produced by the rapid magnetic field conversion of rTMS devices can be uncomfortable for some people. Some patients may experience tinnitus after undergoing rTMS treatment. Therefore, healthcare providers typically provide earplugs for patients before they undergo rTMS.
Electrical stimulation of the brain may also cause seizures. However, the likelihood of rTMS-induced seizures is relatively low, about one in 1,000. In fact, research suggests that the risk of seizures from conventional antidepressants is similar to that of rTMS.
One of the most significant limitations of rTMS is its cost and time commitment. rTMS treatment can be expensive, with a full course of therapy costing tens of thousands to 100,000 Hong Kong dollars. At the same time, rTMS requires patients to visit the clinic every day from Monday to Friday, which may not be suitable for working professionals.
A Glimpse into an rTMS Session: A Simulation Experience Before Treatment
rTMS is not a medication; instead, it alleviates depression symptoms by inducing electrical currents through magnetic field conversion, stimulating the DLPFC in the brain.
The treatment process is not immediate. Patients need to undergo approximately 20 minutes of therapy at the clinic every Monday to Friday for six consecutive weeks, with results typically becoming visible after one or two weeks.
Upon arriving at the clinic at their scheduled appointment time, patients complete a questionnaire about their emotions. Clinic assistants then guide them into the rTMS treatment room. Patients are first seated in a specially designed chair, and their head is secured before they are asked to relax.
The doctor puts a unique cap on the patient's head and measures various dimensions of their head to calculate the position of the DLPFC. This cap is carefully stored by the doctor for future treatment sessions.
During the first, tenth, and twentieth sessions, the doctor measures the patient's motor evoked potential to calculate the required electrical dosage for treatment. The doctor stimulates the patient's motor cortex using the device while observing whether their thumb moves in response to the stimulation.
During the actual treatment, the doctor places the device above the DLPFC, calculated earlier. Patients will experience a series of pulses, with a 10-second rest between each pulse sequence. The entire process lasts for 19 minutes. Doctors usually provide earplugs for patients to reduce the disturbance caused by the device's noise. After completing the treatment, patients can leave the clinic and return home to rest.