Psicobiologia dell'aggressività

In order to offer an exhaustive review of the literature concerning the relationship between mental disorders and the tendency to aggressive and violent behaviour, the authors describe the studies on the prevalence of this behaviour among psychiatric patients. After a brief historical introduction and a terminological note on the conceptual boundaries of this topic, the results of the main studies performed in the last thirty years on this subject are reviewed, taking into account both clinical and prison case histories. For each study the methodologies and their limitations are illustrated, paying attention to their social and relational biases. The results of the studies on prison samples indicate a higher prevalence of mental disorders among prisoners, but the possibility of extending these observations is limited by the factors influencing this sample composition: individuals suffering from mental disorders are at greater risk of arrest as a result of the behavioural difficulties determined by the disorder itself and of deficient supportive networks. Studies in the community also show a greater frequency of aggressive and violent behaviour among psychiatric patients, expecially in the presence of alcoholism and drug abuse, both conditions that, per se, expose the abuser to conflict and criminality. A greater risk of aggressive behaviour is also described in patients suffering from psychosis, especially in the case of persecutory delusions, in patients with associated neurological impairment (spectrum of soft neurologic signs) or with abnormal brain electrical activity detectable with EEG, and in patients with disorders characterized by impulsivity. The article concludes with a detailed description of the neurobiological basis of the aggressive behaviour, with indications on the possible efficacy of drugs action on the different neurochemical systems involved. The role of serotonin in the control of impulses, a factor that apparentely influences the whole range of aggressive behaviour, is emphasized.