When depression symptoms continue despite treatment, it can be frustrating and difficult to understand what comes next. You may have taken one medication, waited to see whether it would help, tried another and still found yourself living with symptoms that affect your mood, energy, relationships or ability to function.
Treatment-resistant depression (TRD) is the term commonly used when depression has not adequately improved after multiple appropriate antidepressant treatments. It does not mean your depression is untreatable. It means your current approach has not provided the improvement you need, and it may be time to consider other treatment strategies.
For some people, those options may include fMRI-guided TMS therapy, which takes a different approach by using functional brain imaging and individualized targeting to inform where transcranial magnetic stimulation (TMS) is delivered.
Quick answer: What is treatment-resistant depression?
Treatment-resistant depression generally describes major depressive disorder that has not adequately improved after at least two antidepressant treatments taken at an appropriate dose, for an adequate amount of time and with appropriate adherence.
There is not one universally accepted definition of TRD, but the two-treatment threshold is commonly used in clinical and research settings.
Most importantly, treatment resistance does not mean treatment is no longer possible. Other therapeutic approaches may still help.
How is treatment-resistant depression defined?
There is no single definition of treatment-resistant depression used by every clinician or researcher. However, the U.S. Food and Drug Administration (FDA) and European Medicines Agency have used a commonly accepted definition: an inadequate response to at least two antidepressants despite adequate treatment trials and adherence.
An “adequate” medication trial generally means that the medication was taken at a therapeutic dose for enough time to reasonably evaluate its effect. The exact dose and duration depend on the medication, the individual and the clinical situation.
This distinction matters. Stopping a medication early because of side effects, taking a dose that was not therapeutically adequate or missing doses may make it difficult to determine whether the medication itself was ineffective.
Your clinician may also look beyond the number of medications you have tried. Your diagnosis, symptom severity, duration of illness, previous response to treatment, co-occurring conditions, medication tolerance and other factors can all influence how your depression is evaluated.
The National Institute of Mental Health’s landmark STAR*D study also demonstrated why reassessment becomes increasingly important when initial treatments do not produce remission.
Participants could progress through several treatment levels when earlier approaches were unsuccessful, and the likelihood of remission generally declined as additional treatment steps were required.
If your symptoms have persisted despite antidepressant treatment, learning more about TMS therapy for depression can help you understand one of the non-medication options that may be considered.
Signs you may have treatment-resistant depression
Treatment-resistant depression is not defined by having “worse” depression than someone else. Instead, the pattern of your response to treatment is an important part of the picture.
You may want to speak with your clinician about treatment-resistant depression if:
- You have completed two or more appropriate antidepressant trials without adequate improvement.
- Your symptoms improve somewhat with medication but continue to significantly affect your daily life.
- A medication initially seems helpful, but meaningful symptoms persist or return.
- Side effects make it difficult to continue otherwise appropriate medication treatment.
- You continue to experience symptoms such as persistent low mood, loss of interest or pleasure, changes in sleep, difficulty concentrating, fatigue or changes in appetite despite ongoing treatment.
These patterns do not automatically mean you have TRD. Other factors can affect treatment response, and your clinician may need to reconsider the diagnosis, look for co-occurring psychiatric or medical conditions, review medication adherence or explore other reasons your symptoms have persisted.
It can be helpful to keep a record of the antidepressants you have taken, including the dose, how long you took each medication, side effects and whether your symptoms changed. That information can give your clinician a clearer view of your treatment history.
Why some depression doesn’t respond to medication
Depression is complex, and there is no single biological explanation for why one person responds well to an antidepressant while another does not.
Genetics, neurotransmitter systems, functional brain networks, co-occurring medical or psychiatric conditions, environmental factors and differences in individual biology may all influence how depression develops and responds to treatment.
Many antidepressants affect neurotransmitter systems such as serotonin and norepinephrine. These medications can be effective for many people, but medication is not the only way to influence the systems involved in depression.
Scientists continue to study how those patterns differ among people with depression and whether differences in functional connectivity may help explain variations in treatment response.
This broader understanding of depression is one reason brain-stimulation treatments such as transcranial magnetic stimulation have become important options for some people whose symptoms persist despite medication.
TMS does not work in the same way as an antidepressant. Instead, it uses magnetic pulses to stimulate targeted areas of the brain involved in functional networks associated with depression.
How Neurotherapeutix approaches treatment-resistant depression
At Neurotherapeutix, treatment planning begins by looking beyond diagnosis alone.
Standard TMS therapy typically identifies treatment locations using standardized anatomical measurements or scalp-based landmarks. Neurotherapeutix uses functional imaging and patented technology to take an individualized approach to treatment targeting.
The process begins with resting-state functional magnetic resonance imaging (rsfMRI). This type of functional imaging measures patterns of activity throughout the brain while you are at rest. Those patterns can be analyzed to examine functional connectivity, or how activity in different areas of your brain is related over time.
Neurotherapeutix then uses patented computational brain mapping technology to analyze those connectivity patterns and identify individualized areas of interest based on your functional brain organization.
The fMRI analysis helps identify individualized treatment targets within the patient’s own brain anatomy. These selected treatment locations are uploaded into the neuronavigation system, allowing the clinical team to consistently position the TMS coil over the intended target with millimeter-level precision throughout treatment.
This creates an important distinction between personalized TMS vs. standard TMS. Rather than relying only on a standardized treatment location, Neurotherapeutix uses whole-brain functional imaging and computational analysis to determine where to deliver stimulation for each patient.
For someone with treatment-resistant depression, this approach provides another way to think about treatment after medication has not provided adequate relief.
Research continues to examine how connectivity-based targeting may influence TMS outcomes and how individual differences in functional brain organization may inform treatment.
When to consider fMRI-guided TMS therapy for treatment-resistant depression
fMRI-guided TMS therapy may be worth discussing with our care team when depression has not adequately improved with antidepressant treatment or when medication side effects make other approaches worth exploring.
Whether and when fMRI-guided TMS therapy is appropriate depends on your diagnosis, treatment history, medical history, medications and other individual factors.
A clinical evaluation is important because TMS therapy is not appropriate for everyone, and treatment decisions should be based on your specific circumstances.
fMRI-guided TMS therapy is non-invasive and does not require surgery or anesthesia. Patients can generally return to their usual activities after a session.
If you are wondering whether your treatment history could make TMS an appropriate next step, learning about candidacy for TMS therapy can help you prepare for a conversation with your treatment team.
Frequently asked questions
Have additional questions about treatment sessions, eligibility, side effects or the Neurotherapeutix approach? Explore our frequently asked questions about TMS therapy for more information.
What qualifies as treatment-resistant depression?
Treatment-resistant depression is commonly defined as depression that has not adequately improved after at least two antidepressant treatments despite adequate dose, duration and adherence.
However, there is no single universally accepted definition. Your clinician will consider your complete treatment history rather than relying only on the number of medications you have tried.
How common is treatment-resistant depression?
Treatment-resistant depression is relatively common. Contemporary research estimates that at least 30% of people with depression may meet the commonly used definition of inadequate response to two appropriate antidepressant treatments.
The exact percentage varies among studies because researchers and clinicians have not historically used one universal definition of TRD.
Can treatment-resistant depression be treated without medication?
Medication is not the only treatment option for depression that has been difficult to treat.
Depending on your clinical needs, treatment may include psychotherapy, transcranial magnetic stimulation, electroconvulsive therapy or other approaches. Some patients may use non-medication treatments alongside medication rather than replacing it.
The appropriate approach depends on your diagnosis, previous treatment response, health history and individual needs.
Is fMRI-guided TMS therapy effective for treatment-resistant depression?
TMS is an established, non-invasive treatment option for major depressive disorder, including for patients whose depression has not adequately responded to antidepressant medication.
Treatment response varies from person to person, and no treatment can guarantee a particular outcome.
At Neurotherapeutix, fMRI-guided TMS therapy adds individualized functional brain imaging, computational brain mapping and neuronavigation to inform treatment targeting.
Rather than determining the treatment location using only standardized anatomical measurements, the approach uses information from your individual functional brain organization to guide where stimulation is delivered.
Get started with Neurotherapeutix
Treatment-resistant depression does not mean you have reached the end of your treatment options. It may mean it is time to look at your depression, your treatment history and your next steps differently.
Neurotherapeutix is the only clinic in the United States offering its patented fMRI-guided TMS approach, combining whole-brain functional imaging, computational brain mapping, individualized targeting and neuronavigation to personalize treatment.
If depression symptoms have continued despite previous treatment and you want to explore whether this approach may be appropriate for you, request an appointment with our team at our Upper East Side Manhattan clinic.
