Transcranial Magnetic Stimulation (TMS) is a non-invasive procedure that uses magnetic fields to stimulate nerve cells in the brain, primarily to improve symptoms of major depressive disorder. It is typically considered for individuals whose depression has not improved with antidepressant medications. A common question for those considering this treatment is how long the benefits are likely to last.
Understanding the TMS Treatment Timeline
The active phase of Transcranial Magnetic Stimulation is a structured course of treatment that is separate from the long-term duration of the results. A standard course of TMS typically involves daily sessions, usually five days a week, for a period ranging from four to six weeks. The total number of sessions in this initial phase is commonly between 20 and 30 treatments.
The length of a single TMS session can vary depending on the specific protocol used by the provider. Conventional repetitive TMS (rTMS) sessions usually last between 20 and 40 minutes, though newer, more advanced protocols, such as theta-burst stimulation (TBS), can significantly reduce this time, with some sessions lasting as little as three minutes. Completing the full prescribed course is generally recommended to achieve the most robust and lasting clinical benefit, even if initial improvements are noticed sooner.
Typical Duration of Relief
For patients who respond well to the initial treatment course, the symptom relief provided by TMS can be durable, though it is not considered a permanent cure for depression. The effects often last between six and twelve months for many individuals, with about half of the initial responders still doing well after a full year. Approximately two-thirds of patients who responded to TMS initially still experienced improvement after three months.
Longer-term follow-up studies have shown that a substantial portion of patients can maintain their remission or response status for several years, especially with appropriate follow-up care. One study found that 62.5% of patients who achieved a response remained at that level of improvement through a long-term follow-up period.
Relapse rates vary, but the durability of the TMS response compares favorably to other options for treatment-resistant depression. After a successful course of acute TMS treatment, relapse rates at six months can be as low as 20% in some patient groups. This long-lasting benefit is thought to result from the neuroplastic changes the stimulation induces, which help strengthen the brain’s neural pathways related to mood regulation.
Variables That Affect Longevity
The length of time a patient experiences relief is not uniform and is influenced by several individual and clinical factors. The severity and chronicity of the major depressive disorder being treated play a significant role. Patients with more severe or long-standing treatment-resistant depression may experience a shorter duration of initial relief compared to those with less complex cases.
Adherence to the full initial treatment protocol is another factor that can influence long-term outcome. While missing an occasional session may not negatively affect the final result, completing the full set of treatments is associated with the best chances for sustained remission. Additionally, the presence of co-occurring mental health conditions, or comorbidities, can impact the maintenance of remission.
The specific parameters of the TMS device and the stimulation protocol utilized may also contribute to the durability of the effect. For example, studies have found that factors like a higher stimulation intensity and a greater total number of pulses delivered can be associated with increased efficacy. The patient’s underlying physiology, such as the distance between the scalp and the targeted area of the brain, may also influence the clinical outcome, particularly in older adults.
Options When Symptoms Return
Because depression is a chronic condition, having a strategy for when symptoms begin to return after a successful TMS course is important. When the therapeutic effect begins to wane, the primary options are maintenance treatment or retreatment.
Retreatment (Booster Course)
Retreatment, sometimes called a booster course, involves beginning a new, shorter course of TMS once symptoms have returned to a clinically significant level. This retreatment course is typically shorter than the initial one, often consisting of 10 to 15 sessions. Patients who responded well to the initial course generally respond just as effectively to retreatment, recapturing their prior level of improvement.
Maintenance TMS
Maintenance TMS is an alternative strategy that involves a planned, systematic tapering of sessions after the acute phase to proactively prevent relapse. This can involve scheduling sessions on a weekly, bi-monthly, or monthly basis, depending on the individual’s risk profile and clinical response. This preventative approach of ongoing TMS maintenance has been shown to be more successful in averting a full relapse compared to doing no preventive care at all.