Acquired brain injury (e.g., traumatic brain injury, brain tumour, brain infections) is one of the leading causes of death and disability for children and adolescents. Importantly, injuries affecting the brain in childhood or adolescence appear during a time of development when the brain is particularly vulnerable. Thus, pediatric acquired brain injury does not only impact cognitive functions at the time of injury or onset of disease, but also cognitive functions that are yet to develop. Changes in cognitive function, and in particular executive dysfunction due to acquired brain injury, cause significant real-life disability, yet solid evidence in support of executive functioning interventions for children and adolescents is lacking. In the present study different group-based cognitive rehabilitation interventions will be compared. The aim of the study is to investigate if a group-based "brain training" intervention is able to improve executive function in children and adolescents after acquired brain injury. Efficacy will be assessed immediately after intervention, but also six months after the intervention. The project is in line with international research efforts aimed at establishing more knowledge about how children and adolescents with brain injuries respond to cognitive rehabilitation.

Inclusion Criteria:

• diagnosed with traumatic brain injury, brain tumor or damage by inflammation in the brain
• more than 12 months since injury/illness or more than 12 months since ended cancer therapy
• evidence of executive dysfunction in everyday life

Exclusion Criteria:

• cognitive, sensory, physical, or language impairment affecting the capacity to attend mainstream school and/or complete the training program
• pre-injury neurological disease or psychiatric disorder
• recently detected brain tumor relapse
• unfit for evaluation of outcome (independent evaluation by 2 investigators)
• not fluent in Norwegian language