Fig. 1

Study Design and Procedure. After randomization no drop out or losses occurred. For two participants (one of each group) Event Related Potentials (ERP) data at T2 were not recorded due to technical reasons. T1 = ERP measures before treatment, T2 = ERP measures after treatment. Group: CG = Control Group; EG = Experimental Group. In case of any other treatment already in progress, participants of both groups (EG and CG) were allowed to continue, if the usual treatment remained stable. *¹Different reasons for exclusion were: Lost of study motivation (n = 12), IQ below 70 or Insufficient knowledge of German (n = 8), other neurological / medical conditions (n = 7), left-handed (n = 5), not aged between 12,00–17,00 years (n = 2), relocation or change of school (n = 2), former neurofeedback training (n = 1).