A 4-day concentrated therapy beat unguided online CBT for OCD in a 119-adult trial

A short, intensive form of exposure therapy delivered over four consecutive days reduced obsessive-compulsive symptoms far more than an eight-week unguided online programme, in a randomised trial of 119 adults [s1]. The result is an encouraging data point for a treatment format that aims to pack effective care into a few days — but it comes from a single centre, and the comparison was with a deliberately minimal alternative.

Obsessive-compulsive disorder (OCD) involves intrusive, distressing thoughts (obsessions) and repetitive behaviours or mental acts (compulsions) performed to ease the distress. The best-evidenced psychological treatment is exposure and response prevention, a form of cognitive behavioural therapy (CBT) in which a person gradually faces the triggers of their anxiety without carrying out the compulsion. It works, but it is time-consuming and specialist therapists are scarce, so researchers have tested ways to deliver it more efficiently [s1]. The Bergen 4-day treatment (B4DT) is one such approach: a concentrated, therapist-led course that compresses exposure work into four consecutive days.

What the trial did

This was a single-centre randomised controlled trial that enrolled adults aged 18 to 72 with OCD between May 2024 and August 2025 and followed them for three months [s1]. Of 253 people screened, 119 were randomised one-to-one: 60 to B4DT (including preparatory sessions) and 59 to an eight-week unguided internet-based CBT programme [s1]. Their mean age was 33.5 years and 66.4% were women [s1]. People with schizophrenia, bipolar disorder, acute suicidality, substance dependence, or recent changes to psychiatric medication were excluded [s1].

The main outcome was the change in OCD symptom severity on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the standard clinician-rated measure, assessed by evaluators who did not know which treatment each person had received [s1]. Secondary measures covered self-reported symptoms, quality of life, depressive symptoms, functioning and treatment satisfaction [s1].

What it found

The concentrated therapy came out clearly ahead. At the end of treatment, the B4DT group's Y-BOCS scores fell by 7.9 points more than the internet group's (95% confidence interval −9.7 to −6.0), a difference the authors classed as a large effect (Hedges g −1.6) [s1]. The gap narrowed but held at three months, where B4DT led by 5.6 points (95% CI −7.8 to −3.4; Hedges g −1.0) [s1].

The response figures tell the same story in plainer terms. At three-month follow-up, 61.4% of the B4DT group (35 of 57) were classed as responders, against 25.0% of the internet group (11 of 44) [s1]. Remission — scoring low enough to be judged largely symptom-free — was reached by 42.1% on B4DT (24 of 57) versus 13.6% (6 of 44) [s1]. Secondary outcomes consistently favoured the concentrated treatment [s1]. The trial was registered in advance [s2].

How to read it

The design is a genuine strength: this was a randomised trial with masked assessors and an intention-to-treat analysis, so the headline comparison is not easily explained away by wishful scoring or dropouts [s1]. For people facing long waits for OCD therapy, the idea that a well-run four-day course can produce large, durable symptom reductions is important.

The caveats sit in what B4DT was compared against. The alternative was unguided internet CBT — a self-directed programme with no therapist support — which is one of the lower-intensity options available and a demanding thing to complete alone. Beating it is not the same as beating standard, therapist-delivered CBT or medication, and the trial does not tell us how B4DT stacks up against those [s1]. It was also run at a single centre, by a team closely associated with the method, and followed people for only three months, so durability beyond that and reproducibility elsewhere remain open questions. Response and remission were calculated on the participants assessed at follow-up rather than everyone randomised, which tends to flatter both arms. For background on what the wider evidence base says, see our explainer on what helps OCD and intrusive thoughts.

What to watch

The questions now are whether concentrated treatment holds up against a stronger comparator — guided internet therapy, conventional weekly CBT, or an SSRI — whether the gains last past three months, and whether other centres can match the results. The promise of compressing effective OCD care into a few days is real; this trial strengthens it without settling where the format belongs in routine treatment.

This article describes research and is not medical advice. Decisions about treating OCD belong with a qualified clinician. If you or someone you know is struggling, help is available: in the US, call or text the 988 Suicide and Crisis Lifeline; in the UK and Ireland, call Samaritans on 116 123. Elsewhere, contact a local crisis line or your doctor.