Aggressive behavior in schizophrenia: relationship to age of onset and cortical atrophy

Aggressive behavior is a common feature of schizophrenia and is associated with the presence of 'soft' neurological signs. Since early age of onset of schizophrenia has been found to be associated with the negative syndrome, which according to Crow (1982) is related to structural brain abnormalities, I predicted that early age of onset may be a biological risk factor for aggressive behavior in the disease. To test this hypothesis, I investigated in 52 chronic institutionalized schizophrenic patients (mean age = 32.8 years; SD = 8.0), the association between age of onset of the disease and the severity of belligerent behavior. The age of onset was judged from the patient's histories as the age at which florid symptoms first emerged. Patients with early onset schizophrenia had a significantly higher belligerent score compared to those with later-onset schizophrenia (p < .05). These findings support the hypothesis of an association between early age of onset of schizophrenia and the risk of aggressive behavior and suggest, furthermore, that schizophrenic symptoms which emerge early may predict a higher risk of aggressive behavior. Furthermore, this study suggest that the neurochemical mechanisms which underlie the early emergence of symptoms may also predispose to aggressive behavior in schizophrenia. Specifically, since aggressive behavior has been linked to impairment of serotonergic (5-HT) functions, I propose that the timing of onset of schizophrenia may be partly associated with dysregulation of the 5-HT system. In a second study, I investigated whether schizophrenic patients with aggressive (suicide) behavior are characterized by more extensive brain damage and hence greater degree of cerebral atrophy on CT scan. The study, which involved 26 schizophrenic patients (mean age: 31.3 years; SD = 6.8), revealed that patients with aggressive behavior had a significantly greater degree of parieto-occipital atrophy on CT scan (p < .05). In contrast, ventricular size and prefrontal cortical atrophy did not distinguish aggressive from nonaggressive patients. These findings suggest that cortical atrophy may be a neuroradiological marker of aggressive behavior in schizophrenia.