This study investigates the psychophysiological correlations of aggression and response to aversive stimuli in a population of 133 children clinically diagnosed with conduct disorder (CD) and/or attention-deficit/hyperactivity disorder (ADHD). Data was gathered about participants' level of aggression through the Reactive-Proactive Aggression Questionnaire (RPQ). The stimuli that were presented to the participants included 1) a loud sound, 2) threatening photographs from the International Affective Picture System (IAPS), and 3) the Trier Social Stress Task (TSST). Participants' psychophysiological features of heart rate and galvanic skin conductance were measured and analyzed in relation to their RPQ scores and clinical diagnosis.

Inclusion Criteria:

1. Subjects between ages 7 and 16 years
2. Subjects who fulfil all criteria for a DSM-IV diagnosis of ADHD, conduct disorder, or oppositional defiant disorder
3. Subjects with willingness to participate in a randomized, double-blind controlled trial
4. Subjects with complete written, informed parental consent and child assent
5. Subjects with IQ of 70 or more

Exclusion Criteria:

1. Subjects who have IQ in the below 70
2. Subjects who are younger than 7 years old or older than 16 years old
3. Those without written parental consent
4. Those with brain pathology such as serious head injury, epilepsy, etc.

The study involves children and adolescents diagnosed with disruptive behaviour disorder (DBD, i.e. conduct disorder or oppositional defiant disorder) or attention deficit / hyperactivity disorder (ADHD, i.e. combined type or ADHD predominantly inattentive type or ADHD predominantly hyperactive-impulsive type).