Transcranial Magnetic Stimulation (TMS) is a non-invasive treatment for Major Depressive Disorder (MDD), often used when standard antidepressant medications have not provided adequate relief. TMS uses magnetic fields to stimulate nerve cells in the brain, offering a targeted approach to mood regulation. People considering TMS often worry whether the treatment could actually make their depressive symptoms worse. While clinical worsening is rare, understanding the treatment experience is important for managing expectations and ensuring safety.
How Transcranial Magnetic Stimulation Targets Depression
TMS works by employing a coil placed near the scalp to generate rapidly changing magnetic fields, which painlessly induce small electrical currents in a localized area of the brain. The FDA has approved this therapy for treatment-resistant depression in adults and adolescents. The targeted area is typically the left dorsolateral prefrontal cortex (DLPFC), a region linked to mood control and executive function.
In people with depression, the DLPFC often shows reduced activity, contributing to symptoms like low mood and lack of motivation. The magnetic pulses aim to increase the excitability and activity of these underactive neurons. This induced activity is believed to normalize brain function and signaling between the DLPFC and deep brain structures involved in emotional processing. The sustained therapeutic effect of TMS is achieved through neuroplasticity, the brain’s ability to create new neural connections and pathways.
Addressing the Core Concern: Worsening Depressive Symptoms
Clinical studies indicate that TMS does not cause a long-term worsening of depression; instead, it leads to improvement or remission in many patients. Cases where depression appears to worsen during treatment are rare and often involve temporary phenomena. It is important to distinguish between true clinical deterioration and a common, temporary experience known as the “TMS dip.”
The TMS dip is a transient phase where 20 to 25% of patients report a temporary spike in symptoms, such as increased sadness, anxiety, or fatigue. This dip typically occurs around the second or third week of the multi-week course. It usually resolves on its own within a few days to a week. This temporary exacerbation is thought to be a sign that the brain is adjusting to the magnetic stimulation and resulting neural changes. This initial disruption does not predict the final outcome of the treatment.
A psychological phenomenon can also be perceived as worsening symptoms if a patient does not immediately feel better. High anticipation for relief from a new therapy can lead to disappointment when immediate improvement does not materialize. This disappointment may mimic a worsening of depression. Furthermore, a thorough diagnostic assessment is necessary before starting TMS. Protocols for unipolar depression may inadvertently trigger manic or hypomanic symptoms in individuals with undiagnosed bipolar disorder, highlighting the importance of a correct initial diagnosis.
Common and Rare Physical Side Effects
The physical side effects associated with TMS are mild, temporary, and localized, distinct from mood changes. The most frequently reported adverse effects include mild headaches and discomfort or pain at the stimulation site on the scalp. These sensations often occur during the first few sessions as the individual acclimates to the procedure, but they diminish as treatment progresses.
Patients may also experience minor muscle contractions or twitching in facial muscles, such as the jaw or eyelids. This is a direct result of the magnetic pulses exciting superficial nerves near the treatment area. The TMS device produces a loud clicking noise with each pulse, requiring the use of earplugs during sessions to protect hearing. Patients may also experience lightheadedness or temporary sleep disruption.
The most serious, though rare, risk associated with TMS is the induction of a seizure. The probability of a seizure is low, estimated to be less than 0.1% of patients, and is lower than the risk associated with some common antidepressant medications. Rigorous patient screening is performed to mitigate this risk. Screening includes reviewing medical history for factors like epilepsy, alcohol use, or certain medications.
Patient Protocols for Monitoring and Reporting Changes
Consistent communication with the treatment team is essential to the TMS protocol. Patients should monitor and track changes in their daily life, including sleep patterns, appetite, mood fluctuations, and any physical discomfort. This detailed reporting helps clinicians understand the patient’s response to the therapy and identify potential issues early.
Patients must immediately report any sharp increase in anxiety, persistent physical side effects like severe headaches, or any thoughts of self-harm to their provider. If negative symptoms arise, the clinician can adjust treatment parameters, such as changing the intensity, frequency, or coil placement, to better suit the individual’s response. The patient and clinical team work together to ensure safety and maximize the therapeutic benefits of TMS.