A Preliminary Examination of Acceptance and Commitment Therapy Versus Exposure and Response Prevention for Patients with Obsessive-Compulsive Disorder on an Optimal Dose of SSRIs: A Randomized Controlled Trial in Iran.

Researchers in Iran split adults with OCD into three groups. All stayed on their usual SSRI pills. One group added twelve weekly ACT sessions. Another added twelve weekly ERP sessions. The third kept pills only.

Doctors rated OCD severity before and after the 12-week program. They also checked psychological inflexibility — how stuck the person felt when urges showed up.

Both ACT plus SSRI and ERP plus SSRI cut OCD symptoms more than pills alone. ACT also lowered psychological inflexibility, while ERP did not.

The gains were modest but clear. The study was small, yet the pattern held for every participant who received the extra therapy.

Lappalainen et al. (2015) showed web-based ACT alone can slash depression with almost no coach contact. Mehdi’s team now shows ACT plus SSRI also helps OCD in face-to-face format. Same core therapy, new setting and diagnosis.

Wetterneck et al. (2006) used ERP in a single-case design and saw tics disappear fast, but some returned within three months. Mehdi’s RCT finds ERP still works when paired with SSRI, giving longer hope.

Arwert et al. (2020) tracked kids who over-predicted ERP distress and found they improved quickest. Mehdi did not measure expectancies, so we don’t know if the same speed boost applies to adults.

If your adult client is stable on an SSRI but still stuck in rituals, adding either ACT or ERP can nudge symptoms down. ACT gives the bonus of loosening rule-governed behavior, so consider it when rigidity is high. Start with one session per week for twelve weeks, measure OCD severity each month, and watch for drops in both compulsions and inflexibility.