Comparing Unified Transdiagnostic Intervention with Acceptance and Commitment Therapy on Sensory Processing Sensitivity, Interpretive Bias, and Experiential Avoidance among Individuals with Functional Seizures

The aim of this study is to compare the effectiveness of Unified Transdiagnostic Intervention and Acceptance and Commitment Therapy on sensory processing sensitivity, interpretive bias, and experiential avoidance in individuals with functional seizures.

This study is a randomized quasi experimental trial with parallel groups and a control group involving 45 participants. Participants will be allocated to three groups using block randomization with a 1:1:1 allocation ratio. Outcome assessors will remain blinded to group allocation. The study phase is not applicable.

The study will be conducted at Razi Psychiatric and Neuropsychological Center in Tabriz, Iran. After screening and obtaining informed consent, participants will be randomly assigned to study groups. Assessments will be conducted at pretest, posttest, and three month follow up by outcome assessors blinded to group allocation.

Individuals with functional seizures aged 18 to 55 years, diagnosed by a psychiatrist or neurologist, with stable medication during the previous three months, ability to read and write Persian, and informed consent will be included. Individuals with severe psychotic disorders, severe neurological comorbidities, inability to participate regularly in treatment sessions, or changes in psychiatric medications during the study will be excluded.

The first group will receive Unified Transdiagnostic Intervention in 12 weekly group sessions. The second group will receive Acceptance and Commitment Therapy in 8 weekly group sessions. The control group will remain on a waitlist and will not receive structured psychological intervention during the study period.

Sensory processing sensitivity; interpretive bias; experiential avoidance

In this study, block randomization with a 1:1:1 allocation ratio will be used. The unit of randomization is the individual participant. After confirming eligibility criteria and obtaining informed consent, participants will be randomly assigned to one of three groups: Unified Transdiagnostic Intervention, Acceptance and Commitment Therapy, or waitlist control group. The random allocation sequence will be generated using statistical software and equal-sized blocks to ensure balanced group sizes. Randomization will be performed by an independent research assistant who is not involved in outcome assessment or intervention delivery. Allocation concealment will be maintained using sequentially numbered, opaque, sealed envelopes. Group assignment will only be revealed after the participant is formally enrolled in the study. Outcome assessors will remain blinded to group allocation.

In this study, outcome assessors and data collectors will be blinded to participants’ group allocation. Random assignment will be conducted by an independent researcher, and allocation information will be kept in sealed opaque envelopes. During the pretest, posttest, and follow-up assessments, evaluators will only have access to participants’ research codes and will remain unaware of the intervention group assignment. Data analysis will also be conducted using anonymized coded data. Due to the nature of the psychological interventions, blinding of participants and therapists is not feasible, as participants are aware of the type of treatment they receive and therapists directly administer the interventions. However, standardized instructions, structured treatment protocols, and blinded outcome assessment will be used to minimize potential bias.

Deidentified participant data, study protocol, statistical analysis plan, informed consent form, data dictionary, and analysis codes will be available for sharing after completion of the study and removal of identifiable participant information.

The data and documents will be available from six months after publication of the study results for a period of five years.

Researchers, faculty members, graduate students, and investigators affiliated with academic and scientific institutions may request access to the data and study documents.

The data and documents may only be used for scientific, research, and educational purposes. Applicants must submit a formal request and agree to use the data solely for approved research objectives while maintaining participant confidentiality.

Applicants may contact the principal investigator, Ali Khademi, through the academic email address below to request access to the data and documents. Email: Ali.khademi@iau.ac.ir

After receiving a formal request, the application will be reviewed by the principal investigator. If the research purpose is approved and confidentiality requirements are met, the requested data and documents will be provided within four weeks.