Verbal aggression, physical aggression and inappropriate sexual behaviour following brain injury

Two critical issues concerning serious disorders of interpersonal behaviour following brain injury were investigated over four studies. For the first time, verbal aggression, physical aggression and inappropriate sexual behaviour were shown to be better conceptualised as distinct forms of disordered behaviour, rather than reflecting a single dimension of behavioural dyscontrol. Study 1 demonstrated the psychometric reliability and validity of the BIRT Aggression Rating Scale (BARS) – a new observational tool with which to systematically and contemporaneously record aggressive behaviours. Study 2 used data from the BARS and measures of inappropriate sexual behaviour exhibited by 152 participants with brain injury undergoing residential neurobehavioural rehabilitation. Principal component analysis revealed a clear separation between aggression and inappropriate sexual behaviour. Furthermore, a distinction between verbal and physical aggression was also justified. These results were replicated in study 3 using observed behavioural recordings on the BARS and the St Andrew’s Sexual Behaviour Assessment (SASBA) in a separate larger sample. It is recommended that these distinctions be reflected in future research. The second critical issue was addressed across the four studies and concerned the neurocognitive correlates of each type of behaviour. Males showed an increased risk for all three behaviours, while poorer verbal skills, impaired self-awareness and poorer social participation were consistently associated with both types of aggression only. Other measures of neurocognitive function and emotional status were not significant predictors within multivariate analyses. Study 4 addressed potential links to executive function in a subsample of 86 participants. Excessive rule violations on the D-KEFS Tower Test were associated with the presence of verbal aggression and inappropriate sexual behaviour. Scores on the D-KEFS Verbal Fluency Test had an unexpectedly positive relationship with the presence of all three behavioural conditions, perhaps indicating the importance of behavioural drive. The implications for clinical work and further research are discussed.