Effectiveness of Mindfulness-Based Cognitive Therapy on Planning, Sustained Attention, and Cognitive Flexibility in Adults with Attention-DeficitHyperactivity Disorder

Evaluate the effectiveness of Mindfulness-Based Cognitive Therapy in improving three core cognitive domains in adults with Attention-Deficit/Hyperactivity Disorder

Randomized clinical trial with parallel groups and waiting list control. After screening, 40 eligible individuals were randomly assigned to either MBCT (8 group sessions; n=20) or wait list control (n=20). Due to the nature of the intervention, blinding of participants and therapists will not possible; however, the outcome assessor (and, where possible, the data analyst) will be blinded to group allocation.

The study will conducted at the Counseling Center of Persian Gulf University (Bushehr). Eligible participants will randomized to MBCT or waitlist control and assessed at pretest, posttest, and 2-month follow-up. Although participant/therapist blinding will not feasible, the outcome assessor will blinded via group coding.

Adults with ADHD will recruited from the Persian Gulf University Counseling Center (Bushehr). Inclusion: age 18–40; adult ADHD confirmed via clinical assessment/DSM-5-TR and validated measures (Barkley); written consent; able to attend sessions and complete assessments; no active psychosis or neurological disorder. Exclusion: >2 absences; major medication/psychotherapy changes; acute episodes (e.g., mania/psychosis); withdrawal or incomplete posttest/follow-up.

Intervention group: Mindfulness-based cognitive therapy, control group receives no intervention.

Planning; sustained attention; cognitive flexibility

After entering the screening and entry conditions, participants will be randomly assigned to two groups: "Mindfulness-Based Cognitive Therapy (MBCT)" and "Waiting List Control". The randomization method is simple randomization (simple randomization) and the randomization unit is considered to be individual (individual level). This means that each participant will be independently placed in one of the two groups. The allocation sequence will be created using SPSS software and the Random Number Generator function. The final list of allocations will be prepared by an independent researcher who has no intervention in the evaluation process. For allocation concealment, the group codes (A and B) will be placed in opaque and sealed envelopes and the envelopes will be opened in order based on the sequence of companies' arrival to minimize the possibility of bias in allocation. The assessors of the tests (TOL, CPT, WCST) will be blinded to the company grouping. Stratified randomization (stratified randomization) is not used in this study because the sample size was limited and population characteristics (gender, age) are matched between groups.

Due to the nature of the group-based psychological intervention (MBCT) and the inclusion of a waitlist control group, blinding of participants and the therapist to group allocation will not be feasible. Participants will be directly aware of whether they are receiving the therapeutic sessions or are assigned to the waitlist, and the therapist will naturally be aware of delivering the intervention. However, to minimize assessment bias, blinding will be implemented at the level of outcome assessors and/or data analysts. Participants: Prior to enrollment, all participants will be provided with a full explanation of the study objectives, procedures, group conditions (MBCT intervention versus waitlist control), and the assessment schedule. Written informed consent will be obtained. Therefore, participants will not be blinded. Interventionist/Therapist: MBCT sessions will be delivered by a licensed therapist. Given the therapist’s direct role in administering the intervention, blinding will not be possible. Principal Investigator and Research Team: The principal investigator will be involved in study processes (e.g., study design, supervision of implementation, coordination of sessions) and, due to the operational nature of the trial, will be aware of group allocation. To reduce potential bias, the principal investigator will not be directly involved in outcome assessments. Data Collectors and Outcome Assessors: Cognitive assessments, including the Tower of London (TOL), Continuous Performance Test (CPT), and Wisconsin Card Sorting Test (WCST), will be administered at all three time points (pre-test, post-test, and follow-up) by trained assessors who will be blinded to group allocation. To maintain blinding, group assignment will not be recorded on assessment forms, and participants will be instructed to refrain from disclosing their treatment status during testing.

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