CTBS and ITBS are two newer brain stimulation methods changing how depression, anxiety and other mental health conditions are treated. While both fall under a wider technique called Theta Burst Stimulation (TBS), they work in different ways and produce very different effects in the brain.
These stimulation protocols are part of the advanced treatment options offered at Neuralia TMS. By delivering short magnetic bursts to targeted brain areas, CTBS and ITBS allow for faster sessions and focused outcomes. Understanding how CTBS vs ITBS differ is important when considering which type of brain stimulation may better support your recovery.
Key Takeaways
- CTBS and ITBS are two forms of theta burst stimulation with different effects on brain activity.
- CTBS lowers brain excitability, while ITBS increases it, each targeting different sides of the brain.
- TBS sessions are short, and changes in brain activity can appear within minutes. Research is ongoing into TBS for conditions like OCD, psychosis, and substance use.
At Neuralia, we focus on proven treatments supported by clinical evidence and tailored care. If you’re looking for alternatives to medication or want to explore options that fit your needs, our team can walk you through what’s available and what might be right for you.
What are CTBS and ITBS?
CTBS and ITBS are two structured formats of theta burst stimulation (TBS), a fast-developing approach within the field of transcranial magnetic stimulation. Traditional rTMS delivers pulses at a steady rate.
TBS uses high-frequency bursts grouped into short trains to mimic the brain’s natural theta rhythm. This allows stimulation to be delivered in just a few minutes without reducing its impact.
Theta rhythms refer to electrical oscillations in the cortex around 5 Hz. These waveforms are active during sleep, memory formation and emotional regulation. Repeating this pattern through targeted stimulation allows TBS to interact with how the brain processes and regulates internal signals.
The standard stimulation protocol involves 3 pulses delivered at 50 Hz (within each burst), repeated every 200 milliseconds for a total of 600 pulses per session.
CTBS (Continuous Theta Burst Stimulation)
CTBS, or continuous theta burst stimulation, applies these bursts without breaks. The uninterrupted pattern is designed to reduce cortical excitability by interrupting overactive signalling between neurons.
This inhibitory response has been observed in both the human motor cortex and prefrontal cortex, based on neuroimaging and post-stimulation activity tracking. While CTBS is generally associated with suppression, some findings suggest the effects of CTBS may vary based on the targeted network and baseline activity.
CTBS is currently used in clinical practice for selected psychiatric and neurological conditions. It’s also part of several protocols that hold FDA clearance for treating depression. The effects of CTBS are influenced by variables like stimulation intensity, timing and baseline cortical reactivity. Most protocols are completed in under five minutes and don’t require recovery time.
Many patients describe CTBS sessions as tolerable, with only minor scalp sensation or tapping. Because the bursts are delivered in a compact window, the procedure fits easily into daily routines. Functional studies such as magnetic resonance imaging and resting-state functional connectivity scans have been used to observe how brain networks behave following CTBS.
ITBS (Intermittent Theta Burst Stimulation)
ITBS, or intermittent theta burst stimulation, uses the same pulse structure but adds short pauses between trains of bursts. This change shifts the neurophysiological effect, often resulting in a boost to cortical excitability.
Intermittent TBS is designed to activate under-functioning areas. Like CTBS, the effect of ITBS may depend on individual brain networks and underlying activity patterns.
ITBS is also widely used in clinical care and included in multiple FDA-approved and research-supported protocols for mood disorders. The ITBS protocol typically uses 2-second burst trains followed by 8-second rests, repeated until the full 600 pulses are delivered. The entire session takes about 3 to 4 minutes.
Compared to traditional high-frequency repetitive transcranial magnetic stimulation, ITBS offers a more efficient option with equal or stronger outcomes in certain populations. The short session length, minimal discomfort and evidence of neuroplastic changes have made accelerated intermittent theta burst stimulation a subject of growing interest in brain-based mental health care.
What are the Main Differences Between CTBS and ITBS?
CTBS and ITBS differ in how they affect the brain, how stimulation is delivered, and what each is designed to achieve. CTBS delivers continuous bursts to calm overactive brain regions. ITBS delivers spaced bursts to activate areas that are underactive. Both use the same pulse structure but create opposite effects.
| CTBS (Continuous) | ITBS (Intermittent) | |
|---|---|---|
| Effect on Brain Activity | Produces a steady decrease in neural firing to settle overactivity. | Promotes stronger neural firing to enhance underactive regions. |
| Session Duration | Completed within approximately three minutes. | Also lasts about three minutes per session. |
| Common Uses | Often applied when brain networks show excessive stimulation, such as in anxiety or trauma-related disorders. | Commonly used when mood-regulating regions show reduced activation, such as in depression. |
| Treatment Outcome Goals | Aims to quiet overresponsive neural circuits. | Aims to strengthen communication in low-activity circuits. |
What does a Typical CTBS or ITBS Protocol Look Like?
CTBS and ITBS protocols are structured over a two-week period, with stimulation delivered once per day on weekdays. Most treatment plans involve 10 carefully scheduled sessions using burst-based magnetic stimulation applied to specific brain regions. Outcomes are monitored across the course, with reassessment after completion.
Number and Frequency of Sessions
- Standard treatment involves 10 sessions of either intermittent theta burst stimulation or continuous theta burst stimulation, delivered daily, five days a week.
- Accelerated formats may deliver multiple rounds of theta burst stimulation per day, spaced by 15 to 60 minutes, to manage cumulative effects.
- Each protocol uses a fixed number of bursts, guided by clinic-established parameters for stimulation intensity, duration and type.
What Happens During Treatment?
- Patients are seated comfortably while the coil is positioned over the targeted cortex, usually in the dorsolateral prefrontal cortex or primary motor cortex.
- The assigned stimulation protocol is applied using either the continuous or intermittent format, depending on whether CTBS or ITBS is being used.
- Stimulation parameters, including location and dose, are adjusted according to clinic guidelines and the patient’s baseline response.
- The full treatment session usually lasts under five minutes, with no recovery time required.
Follow-up and Maintenance
- After completing 10 sessions, a follow-up is conducted at the four-week mark to assess symptom change and the overall effect of stimulation.
- Additional ITBS sessions may be offered if symptom relief is incomplete or short-lived.
- Maintenance options may include single-session boosters, scheduled check-ins, or imaging such as functional magnetic resonance scans to track progress in functional connectivity following theta-burst stimulation.
Can CTBS and ITBS Be Dangerous?
CTBS and ITBS are safe when delivered under medical supervision, but some risks exist and are addressed through strict protocols. During the initial assessment, clinicians evaluate the patient’s motor threshold to determine the safe intensity for stimulation. This helps reduce the chance of adverse events when targeting sensitive areas through patterned magnetic bursts.
Most side effects are mild and temporary. These may include discomfort at the site of stimulation, a brief headache or lightheadedness.
Seizures are extremely rare but are considered in patients with neurological vulnerabilities or a history of seizures. Reactions depend on the individual, the target site and the format used. This includes whether continuous theta-burst or intermittent stimulation is applied.
During the course of theta burst stimulation, clinicians monitor the response closely. In rare cases, irregular outcomes have been observed in trials involving stimulation of the human motor cortex and adjacent brain systems. Safety reviews also consider how stimulation may interact with broader networks during stimulation of the human brain, particularly when higher frequencies are used.
Patients undergoing treatment for treatment-resistant depression may be more sensitive to dose or stimulation timing. For this reason, adjustments are sometimes made mid-course based on tolerability, side effects or observed neural response.
Who Shouldn’t Get CTBS and ITBS?
Continuous theta-burst stimulation and intermittent theta-burst stimulation are considered safe for most people, but they’re not suitable in every case. Certain medical or neurological risks may affect eligibility.
People with a history of epilepsy or seizures may be more vulnerable to rare complications. Others who should not receive the use of transcranial magnetic stimulation include those with metal implants in the head or electronic devices that could interfere with treatment. Some medications or medical conditions can lower seizure thresholds or affect how the brain responds.
The effects of CTBS and ITBS depend on stimulation settings and individual brain activity. If a person has unstable symptoms or other risk factors, treatment may not be recommended. Safety also depends on accurately measuring the motor threshold and monitoring responses following stimulation.
What’s the Difference Between TMS and TBS?
TMS and TBS are both forms of non-invasive brain stimulation, but they differ in how stimulation is delivered and how long treatment takes.
Traditional TMS delivers one TMS pulse at a time, usually over 20 to 40 minutes. Continuous TBS, on the other hand, uses rapid bursts of stimulation in short cycles, completing a full session in just a few minutes. Both target specific regions of the brain, but with different timing and intensity.
Some protocols are guided by data from magnetic resonance imaging study findings to improve precision and response. TBS is often used when faster sessions are preferred without reducing effectiveness.
CTBS and ITBS FAQs
How quickly can you see results from CTBS and ITBS?
The effects of CTBS and ITBS start within minutes of the session. CTBS tends to reduce brain activity around 5 minutes after treatment, while ITBS increases it between 5 and 10 minutes after. Depending on the protocol, these effects may last 20 minutes or longer.
What are the long-term effects of CTBS and ITBS?
The effects of a single session may last hours or longer, but long-term benefits usually come from completing a full treatment course. Clinical research is still building around how these protocols work over time, especially for mood and cognitive conditions.
Can CTBS and ITBS be used for conditions other than depression/anxiety?
Current studies are looking at how these therapies may support people with OCD, schizophrenia or psychosis, and whether they could help with substance use recovery. There’s also early interest in their role in cognitive enhancement, but this research is still developing.
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