Obsessive–Compulsive Disorder (OCD) affects millions worldwide and often does not fully respond to standard treatments like SSRIs or Cognitive–Behavioural Therapy (CBT with ERP). Around 30–40% of patients remain treatment-resistant, requiring new approaches.

In recent years, neuromodulation techniques and novel biological strategies have shown promise for OCD management. This article explores the role of repetitive transcranial magnetic stimulation (rTMS), deep TMS (dTMS), theta burst stimulation (TBS), transcranial direct current stimulation (tDCS), and N-acetylcysteine (NAC) in OCD.

🧠 1. Repetitive Transcranial Magnetic Stimulation (rTMS)

• rTMS uses magnetic pulses to stimulate specific brain regions.

• In OCD, the main targets are:

  • Supplementary Motor Area (SMA) – hyperactive in compulsions.

  • Dorsolateral Prefrontal Cortex (DLPFC) – involved in cognitive control.

• Multiple studies show that low-frequency rTMS over SMA can reduce compulsive urges.

• rTMS is non-invasive, outpatient-based, and generally safe.

👉 Limitation: Benefits may take weeks to appear and require multiple sessions.

🔍 2. Deep TMS (dTMS)

• Deep TMS uses H-coils to penetrate deeper into brain circuits compared to standard rTMS.

• Targets the medial prefrontal cortex and anterior cingulate cortex (ACC) — key regions in the OCD network.

• FDA-approved in the US for treatment-resistant OCD (2018).

• Clinical trials show significant improvement in Y-BOCS scores with dTMS, especially when combined with ERP.

👉 Advantage: Reaches deeper circuits that are harder to access with standard rTMS.

⏱️ 3. Theta Burst Stimulation (TBS)

• A newer patterned form of rTMS that delivers bursts of stimulation at theta frequency (50 Hz bursts repeated at 5 Hz).

• Intermittent TBS (iTBS) can increase excitability, while continuous TBS (cTBS) reduces overactivity.

• For OCD:

  • cTBS over SMA shows promise in reducing compulsions.

  • iTBS over DLPFC may improve cognitive flexibility.

• Advantage: Sessions are much shorter (3–5 minutes) compared to conventional rTMS.

🔌 4. Transcranial Direct Current Stimulation (tDCS)

• Uses weak electrical currents applied through scalp electrodes.

• Targets:

  • Orbitofrontal cortex (OFC) and SMA (hyperactive circuits).

  • DLPFC (hypoactive in executive control).

• Small studies show mixed results but promising reductions in OCD symptoms with repeated sessions.

• Advantage: Portable, inexpensive, can be applied in outpatient or research settings.

💊 5. N-Acetylcysteine (NAC)

• A glutamate-modulating agent and antioxidant.

• OCD is linked to glutamatergic dysregulation in the cortico-striatal-thalamo-cortical (CSTC) circuits.

• Clinical trials suggest NAC (1200–3000 mg/day) can reduce obsessions and compulsions, especially as an adjunct to SSRIs.

• Also beneficial in trichotillomania, excoriation disorder, and other compulsive spectrum disorders.

📊 Evidence Snapshot

💡 Key Takeaway

For patients with treatment-resistant OCD, new tools like deep TMS, rTMS, theta burst stimulation, tDCS, and NAC offer hope beyond medications and CBT. While not cures, they represent powerful adjunct strategies that target brain circuits directly.

These approaches should be delivered under specialist supervision and, wherever possible, combined with ERP-based CBT for the best outcomes.

👨‍⚕️ Consultation

I’m Dr. Srinivas Rajkumar T, Consultant Psychiatrist at Apollo Clinic, Velachery, Chennai.
I work with patients who struggle with OCD and treatment resistance, integrating evidence-based psychotherapies and neuromodulation strategies.

📞 Contact: +91 8595155808