This project is an RCT in 51 individuals with mild psychopathology randomly assigned to Acceptance and Commitment Therapy (ACT) or topic discussion group conditions. Participants underwent Diffusion Weighted Imaging (DWI), Experience Sampling Method (ESM) and a Community Assessment of Psychic Experiences (CAPE) questionnaire before and after intervention. Results show no differences between conditions after the intervention in the white matter (DWI) or the amount of psychotic experiences (CAPE). The suspicious mood ESM item showed was significantly changed due to ACT-intervention. Therefore white matter changes do not seem to occur, while mood changes as a result after 12 week intervention.