Cognitive-behavioral and mindfulness-based cognitive therapies for adults with attention-deficit/hyperactivity disorder and cognitive disengagement syndrome: a randomized controlled trial

Abstract

Adult attention-deficit/hyperactivity disorder (ADHD) is frequently accompanied by Cognitive Disengagement Syndrome (CDS), characterized by mental fogginess, slowed processing, excessive daydreaming, and reduced task engagement. This study compared the effects of cognitive behavioral therapy (CBT) and mindfulness-based cognitive therapy (MBCT) on self-reported ADHD and CDS symptoms in adults. In this randomized controlled trial, 60 adults meeting DSM-5 criteria for ADHD were assigned to CBT (n = 20), MBCT (n = 20), or a waitlist control group (n = 20). Outcomes were assessed at pretest, posttest, and two-month follow-up using the Persian version of the Barkley Adult ADHD Rating Scale–IV (BAARS-IV). Between-group posttest differences were examined using multivariate analysis of covariance (MANCOVA) controlling for baseline scores, and symptom changes over time were evaluated using repeated-measures analysis of variance. The analyses indicated significant between-group differences in self-reported ADHD/CDS symptoms following treatment. Both CBT and MBCT were associated with greater reductions in self-reported symptoms than the waitlist control group, with the most consistent improvements observed for inattention and CDS. Improvements in inattention and CDS were largely maintained at the two-month follow-up. Effects on hyperactivity and impulsivity were smaller. No statistically significant differences were detected between CBT and MBCT on the primary symptom outcomes. However, because the trial was not designed or powered as an equivalence or non-inferiority study, this finding should not be interpreted as evidence that the two interventions are equivalent. CBT and MBCT were each associated with greater reductions in self-reported ADHD and CDS symptoms than the waitlist control condition, particularly in attention-related and cognitive disengagement domains. No statistically significant differences were detected between the two active interventions; however, because the trial was not designed or powered as an equivalence or non-inferiority study, this finding should be interpreted as an absence of detected difference rather than evidence of comparable efficacy. Given the modest sample size, reliance on self-report outcomes, use of a waitlist control condition, and the single-group delivery of each active intervention, these findings should be regarded as preliminary and interpreted cautiously. The trial was prospectively registered in the Iranian Registry of Clinical Trials (IRCT20250927067383N1).