Goal Management Training (GMT) for Improvement of Cognitive Control Function After Acquired Brain Injury

The goal of this clinical trial is to investigate predictors of treatment outcome, and the effect of individual treatment components of Goal Management Training (GMT) for improvement of cognitive control function in people with acquired brain injury (ABI). Primary aim: To identify demographic, clinical and cognitive predictors of treatment response in Goal Management Training after acquired brain injury (ABI)? Secondary aims: To investigate the effects of a) extended cuing (via a smartphone) and b) a booster module? * All included participants will receive Goal Management Training in groups of 4-6 patients, as implemented in a rehabilitation hospital setting (St. Olavs Hospital, Trondheim University Hospital). The standard treatment ("GMT Usual") consists of 10 sessions, delivered as 2 sessions a day, one day per week, over 5 weeks. * All participants will be asked to complete self-report measures and performance-based cognitive testing at baseline (T1), immediately after the main treatment period (T2), at 6 months (T3), and 1 year (T4) after treatment. * After baseline assessment, 50% of participants will be randomized to receive extended cuing through a smartphone application ("GMT Cuing") - intended to facilitate the effect of between-session tasks (homework) completed by the participants. These participants will, in addition to the standard treatment, on a daily basis receive a message that says "STOP" as a reminder to do their home assignments. * After completion of the 10 GMT sessions and the first post-treatment assessment immediately after the main treatment period, 50% of the participants will be randomized to receive an additional booster module ("GMT Boost") 3 months after the last ordinary GMT module - intended to facilitate a prolonged treatment response. The remaining 50% will receive no booster module ("GMT No Boost") * Randomization will be carried out on treatment group-level (all patients in the same group receive the same treatment). The total anticipated sample size is N = 116 patients. * The Global Executive Composite (GEC) score derived from BRIEF-A will be used as the primary outcome measure. A selection of other included measures will be used as secondary outcome measures.