App-based mindfulness meditation training enhances cognitive flexibility and modulates ACC and medial frontal gyrus activation during task switching in adolescent OCD

Background: Cognitive flexibility is a core executive function often impaired in individuals with obsessive‐compulsive disorder (OCD). Mindfulness‐based interventions have been hypothesized to improve cognitive flexibility and may be a promising adjunctive intervention for adolescents with OCD. The current study examines which cognitive neurophysiological processes underlie mindfulness‐based interventions in cognitive flexibility. Methods: In a randomized, interviewer‐blind design, 76 adolescents (aged 10‐19) with diagnosed or suspected OCD were enrolled. After exclusion, the final sample included 53 participants (45.3 % male). Participants were randomly assigned to either a mindfulness training group or an active control group (audiobook listening). Cognitive flexibility was assessed using a task‐switching paradigm while EEG data were collected. Multivariate pattern analysis (MVPA) and source localization were applied to decomposed EEG data, enabling control of inter‐individual variability. Results: The mindfulness group showed significantly reduced switch costs compared to the control group, indicating improved cognitive flexibility. The MVPA revealed group‐specific decoding performance effects in fractions of EEG data reflecting response selection processes in a time window of 300‐400 ms. In this time frame, the mindfulness group showed differential activation in the medial frontal gyrus and anterior cingulate cortex. Conclusions: This study provides evidence that an app‐based mindfulness meditation training can enhance cognitive flexibility in adolescents with OCD through modulating stimulus‐response selection processes in frontal cortices.