How to Deliver High-Frequency rTMS for Bipolar Depression
How should clinicians select and treat adults with bipolar depression using the high-frequency rTMS protocol studied here?
Adults with bipolar I or bipolar II depression often have limited treatment options and concern for treatment-emergent affective switching complicates care. This guide applies to outpatient clinicians considering a standard high-frequency repetitive transcranial magnetic stimulation approach for bipolar depression in patients already maintained on mood-stabilizing treatment.
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Confirm bipolar depression eligibility
Assess eligibility with a clinical psychiatric interview and the Mini International Neuropsychiatric Interview. The studied population included adults aged 18 years or older with DSM-5 bipolar disorder type I or II, a current depressive episode lasting at least 4 weeks but less than 3 years, MADRS score of 20 or higher, YMRS score below 12, and CGI-Severity score of 4 or higher at screening.
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Screen for exclusion criteria and safety risks
Do not proceed with this protocol if the patient has another primary Axis I diagnosis or an Axis II disorder judged likely to interfere with participation. Exclude patients with antidepressant use or discontinuation within 2 weeks, psychotic symptoms, substance abuse or dependence within 6 months, prior nonresponse to electroconvulsive therapy, vagus nerve stimulation, or rTMS, a positive urine drug screen other than benzodiazepines, current suicide risk by investigator judgment, a screening yes on item 4 or 5 of the Columbia Suicide Severity Rating Scale, suicide attempt within the last 12 months, or rTMS-relevant safety concerns such as past head injuries, seizure disorder, or nonremovable metallic implants in or around the head.
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Maintain concurrent mood-stabilizing treatment
Start rTMS only after the patient has been taking a suitable mood stabilizer and or antipsychotic medication clinically used for bipolar disorder for at least 4 days before treatment begins. The study required this concurrent pharmacotherapy throughout treatment, and no treatment-emergent mania or hypomania was observed during the protocol.
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Establish baseline symptom measures
Use MADRS as the primary depression outcome measure and collect baseline HDRS, QIDS, CGI-S, and YMRS ratings before treatment. Assess suicidal ideation with the baseline version of the Columbia Suicide Severity Rating Scale at screening so that change over treatment can be tracked.
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Set motor threshold and left DLPFC target
Determine resting motor threshold using visual left abductor brevis pollicis thumb contraction. Locate the left dorsolateral prefrontal cortex by moving the coil 5.5 cm anteriorly from the thumb contraction site.
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Deliver the stimulation protocol
Administer treatment at 120% of resting motor threshold using 10-Hz stimulation, 4-second trains, and a 26-second intertrain interval. Deliver 75 trains over 37.5 minutes for a total of 3,000 pulses per session, 5 times per week, for up to 35 treatments or until remission criteria are met.
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Adjust only for early intolerability
If the patient cannot tolerate the initial intensity, dose intensity may be reduced to 110% of resting motor threshold during the first week only. Reposition the coil and allow prophylactic acetaminophen or ibuprofen for stimulation site discomfort or pain.
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Monitor response, remission, and manic symptoms during treatment
Follow depressive symptoms over the course of treatment with repeated MADRS assessments and continue YMRS monitoring to detect any emerging hypomania or mania. In this study, response was defined as a 50% or greater reduction in MADRS score and remission as a MADRS score below 10, with the largest reductions toward response and remission occurring after 4 weeks from baseline.
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Define completion and interpret treatment course
Consider patients completers if they finish at least 30 sessions or meet remission criteria before 30 sessions. In this trial, 29 of 31 patients completed treatment, and improvements were seen on MADRS, HDRS, CGI-S, and QIDS, while YMRS scores did not increase.
Clinical Considerations
- This was a small open-label pilot trial without a control group, so the protocol's apparent effectiveness cannot be interpreted as definitive causal proof.
- The study population was restricted to outpatients with bipolar I or II depression who were already taking a suitable mood stabilizer and or antipsychotic medication, so applicability outside that context is limited.
- Observed associations between concurrent lamotrigine or lithium use and MADRS trajectories were not a primary aim and are not sufficient to guide medication recommendations.
- The findings do not establish that other TMS paradigms used in unipolar depression, such as intermittent theta burst stimulation or deep rTMS, would produce the same outcomes in bipolar depression.
Bottom Line
For appropriately screened adults with bipolar I or II depression already maintained on mood-stabilizing treatment, the studied protocol used standard left DLPFC 10-Hz rTMS delivered daily on weekdays for up to 35 sessions, with structured monitoring showing high depressive response and no observed manic switching in this pilot sample.
