The purpose of this study is to determine whether individualized biofeedback of arousal (skin conductance) is effective in the treatment of aggressive behavior problems in children and adolescents with either predominantly impulsive (reactive) and/or high callous unemotional traits (proactive) subtypes of aggression when compared to treatment as usual (TAU), and induces normalization when compared to a group of typically developing children receiving no intervention.

In this study, which is part of the EC FP7 projects Aggressotype (FP7-Health-2013-Innovation-1 602805, Aggression subtyping for improved insight and treatment innovation in psychiatric disorders), the investigators focus on the testing of an innovative, non-pharmacological therapeutic approach for children and adolescents with different subtypes of aggressive behavior problems. Participants will be trained to acquire control over their arousal as measured by skin conductance/electrodermal activity. As aggressive behavior involves a dysregulation of arousal at rest and in response to emotional stimuli (lower electrodermal activity and heart rate, differences in EEG), the individualized acquisition of self-control over ones arousal level might represent a promising therapeutic approach for this kind of disorder.

While trying to control their arousal level, participants receive direct continuous feedback about their physiological state and its changes, and are rewarded for successful manipulation, i.e. up- or downregulation. During transfer trials continuous feedback is omitted. Biofeedback methods are currently used to treat patients with a variety of psychiatric disorders such as ADHD.

The investigators would like to focus on the following questions concerning the effectiveness of this treatment approach:

1. Can participants gain increasing control over their arousal level through biofeedback training of electrodermal activity?
2. Which short- and longer term consequences can be expected from improved self-control over physiological measures of arousal upon aggressive and antisocial behavior problems?

Before the training, all subjects will undergo an extensive pre-treatment assessment as part of the characterization and subtyping of aggression within the large multicenter subtyping studies (EU-Aggressotype and EU-MATRICS). The assessment includes clinical and psychometric measures, neuropsychological testing, fMRI (3 tasks + resting state), MRS (2 voxels) and DTI as well as biosampling (blood/saliva for genetics/epigenetics/hormones). Comparison with a typically developing (TD) control group receiving no intervention will allow to interpret changes in terms of normalisation or compensation.

After completion of this pretest, subjects meeting the inclusion criteria for the arousal-biofeedback treatment study will be randomly assigned to two different treatment arms, either to the experimental arousal feedback condition or to the comparator condition with TAU lasting about 20 weeks. Subjects assigned to the experimental condition will receive 20 sessions (1/week) of arousal (electrodermal activity)-feedback, learning to either in- or decrease levels of electrodermal activity. At the beginning of the first treatment session, a baseline assessment of arousal measures will be done in order to determine the arousal subtype of the participants (hypo- or hyperarousal), and the main direction of individualized training (up- or downregulation). Afterwards, each training will last about 1 hour and consist of several experimental blocks, including feedback as well as transfer trials with EEG and heart rate recorded simultaneously during the sessions. Video clips of emotional and aggressive situations will be used to support regulation of arousal. During the first 10 sessions, all participants will be asked to increase/decrease their electrodermal activity in a proportion of about 2:1 depending on the dominant arousal subtype, in order to train mainly upregulation in patients with hypoarousal, and downregulation in patients with hyperarousal. Subjects in the comparator TAU arm will receive several sessions of psychoeducation and counseling with their parents/caregivers or group training over the 20 weeks.

After the first 10 sessions of feedback training (or several appointments with their parents/caregivers or group trainings in the TAU group) approximately 10 weeks after the beginning of the training, parents/caregivers will be asked to shortly evaluate behavioral measures of aggressive behavior by filling out the MOAS. In the feedback group arousal measures will be reassessed as done at the beginning of the first training to assess stability.

After completion of either the training or the TAU, subjects will undergo post-treatment assessment including again the same teachers and parents reports on behavioral measures, as well as the neuropsychological testing, fMRI and MRS. A follow-up assessment with parents and teachers reports on behavioral measures only will take place 6 months after the end of the treatment phase.

Inclusion Criteria (interventional group):

• ODD/CD diagnosis based on the DSM-5 criteria
• aggression in the clinical range, T > 70 on the aggression or delinquency subscale of the Teacher Report Form (TRF), Youth Self Report (YSR) or Child Behaviour Checklist (CBCL)
• Preferably medication-naive, otherwise medication should be stable for at least 2 months

Inclusion Criteria (typically developing (TD) control group):

• No diagnosis based on the DSM-5 criteria
• aggression below clinical range, T < 70 on the aggression or delinquency subscale of the Teacher Report Form (TRF), Youth Self Report (YSR) or Child Behaviour Checklist (CBCL)

Exclusion Criteria (both groups):

• IQ<80
• a primary DSM-5 diagnosis of psychosis, bipolar disorder, depression or anxiety
• contra-indications for MRI scanning, e.g. presence of metal parts in the body
• epilepsy