background On the basis of the international literature the combined group of inpatients serving a tbs-sentence and forensic outpatients is expected to obtain higher scores on the personality domains of neuroticism and extraversion and lower scores on the domains of altruism and conscientiousness and, when compared to inpatients serving a tbs-sentence, forensic outpatients are sup-posed to report less aggressive behaviour and more socially competent behaviour. Tbs is an abbreviation of the Dutch term 'terbeschikkingstelling' which means 'detained at placed at the disposal of the government. Tbs-patients are treated at tbs-hospitals, which are institutions specialising in forensic psychiatric care.
aim Aggression control therapy, which is used to treat forensic psychiatric patients, needs to be further developed and evaluated. For this purpose a group of violent forensic inpatients (tbs-patients) and forensic outpatients was compared to 'normal groups' with regard to personality traits (according to the 'big five') and with regard to aggressive behaviour and socially competent behaviour. The tbs-patients were also compared to the forensic outpatients. The main aim was to find out whether the personality traits and problem behaviours as mentioned in the literature were applica-ble to a comparable Dutch population.
method The study population consisted of 110 tbs-patients and 69 forensic outpatients all of whom had been had been assigned to aggression control therapy. Subjects were required to complete self-report questionnaires. A checklist (Psychopathy Checklist-Revised) was used to measure per-sonality traits and various aspects of aggressive behaviour and socially competent behaviour.
results Forensic patients obtained higher scores than normal subjects on the personality domains of neuroticism but lower scores on altruism. The scores for extraversion and conscientious-ness were about the same for forensic patients and normal subjects. The completed questionnaires and checklists showed that all the forensic patients showed a greater propensity for becoming angry. Contrary to expectations, outpatients were found to differ from inpatients on several measures (including age). After correction for age, outpatient scores were lower that inpatient scores on the personality domains of openness, altruism and conscientiousness. Outpatients also reported more hostile and aggressive behaviour. The outpatient and inpatient groups did not differ with regard to socially competent behaviour.
conclusions It is possible that these results are attributable to the fact that inpatients live in a structured and controlled environment, whereas outpatients live in a much less rigid environment where aggressive behaviour is permitted more often and/or is reinforced. Furthermore, tbs-patients are inclined to give socially desirable answers because they assume that research outcomes might result in a longer sentence or period of detention. Contrary to expectations, both the group of tbs-patients and the group of forensic outpatients obtained fairly high scores on psychopathy in the Psychopathy Checklist-Revised. Since scores on the Psychopathy Checklist-Revised are known to be good predictors of recidivism, it seems advisable to subject younger violent offenders with psychiatric problems to careful risk-assessment and intervention as early as possible.