The prediction of violence in psychiatric patient populations remains one of the most challenging aspects of work with psychiatric patients .
Accurate assessment depends on the availability of accurate information. This will usually include information obtained from collateral sources such as medical records, informants or police reports. However, the clinical assessment carried out on admission has limited power in assessing the predictors of potential violence among psychiatric patients. Therefore, additional investigations, including psychological testing, and measuring attention, may be required.
Previous research has linked aggressive behavior to certain genetic conditions, impaired socio-emotional information processing, demographic variables (as gender and age) and clinical variables (as diagnosis, presence of mood symptoms, and comorbid substance abuse). An association between aggression and inherent cognitive defects—such as impaired information processing, socio-emotional understanding, and problem-solving skills—has been demonstrated in patients with mental retardation and schizophrenia. Inaccuracy in correctly identifying interpersonal intent, a tendency wrongly to attribute hostile intent to others, as well as a poorer ability to assess the intensity of emotion has also been demonstrated .
On the other hand, the predictors of violence depend on the setting: whereas clinical and psychopathological variables may predict violence in institutional settings, demographic and historical variables are better predictors in community settings and in clinical samples consisting of only high-risk patients.
The complex influence of diagnosis on psychiatric patients’ risk of violence has emerged from a variety of studies in different contexts. First, a diagnosis of schizophrenia (and other severe, enduring psychotic disorders) has been demonstrated unequivocally to increase a person’s risk of violence in comparison to the general population .
Similarly, comorbid substance abuse/dependence dramatically increases the risk of violence in patients with schizophrenia .
Primary diagnosis of substance abuse/dependence has also been identified as a strong predictor of violence in psychiatric patients .
Another factor that appears to elevate the risk of violence in patients with schizophrenia is the presence of neurological damage, e.g., parieto-occipital atrophy, reduced grey matter volume in neural circuits involved in verbal working memory, as well as temporal EEG abnormalities . However, a diagnosis of epilepsy itself has not been proven to increase the risk of violence .
Comorbid substance abuse increases the risk of violence in patients with mental retardation. Furthermore, violent mentally retarded adults have been shown to have larger brain ventricles than their non-violent counterparts, as well as a higher frequency of abnormal EEGs, yet no increased prevalence of seizure disorders (as for schizophrenia) .
This aggressive diathesis can be conceptualized in terms of an imbalance between the “top-down” control or “brakes” provided by the orbital frontal cortex and anterior cingulate cortex, which are involved in calibration of behavior to social cues and predicting expectancies of reward and punishment, and thus modulating or suppressing aggressive behavior with negative consequences, and excessive “bottom-up” “drives” triggered or signaled by limbic regions, such as the amygdala and insula. An emotionally provocative or challenging stimulus that serves as a trigger to the aggressive event will initially be processed by auditory, visual, and other sensory processing centers. At this stage, sensory deficits such as hearing or visual impairment as well as sensory distortions that might be caused by drugs, alcohol, or metabolic disturbances secondary to illness may result in incomplete or distorted sensory impressions, which can increase the likelihood that the stimulus is perceived as threatening or provocative .
Attention is the behavioral and cognitive process of selectively concentrating on a discrete aspect of information, whether subjective or objective, while ignoring other perceivable information. Attention has also been referred to as the allocation of limited processing resources; it is best described as the sustained focus of cognitive resources on information while filtering or ignoring extraneous information. Attention is a very basic function that often is a precursor to all other neurological/cognitive functions .
Hence, its affection may be related to different abnormal behaviors including increased violence tendency. The event-related potential (ERP) is the measured brain response that is the direct result of a specific sensory, cognitive, or motor event. More formally, it is any stereotyped electrophysiological response to a stimulus. The study of the brain in this way provides a noninvasive means of evaluating brain functioning including attention. ERPs are measured by means of electroencephalography (EEG).
The EEG proved to be a useful source in recording brain activity over the ensuing decades. However, it tended to be very difficult to assess the highly specific neural processes that are the focus of cognitive neuroscience because using pure EEG data made it difficult to isolate individual neurocognitive processes. Event-related potentials (ERPs) offered a more sophisticated method of extracting more specific sensory, cognitive, and motor events by using simple averaging techniques. Currently, ERP is one of the most widely used methods in cognitive neuroscience research to study the physiological correlates of sensory, perceptual, and cognitive activity associated with processing information.
The P300 (P3) wave is an event-related potential (ERP) component elicited in the process of decision-making. It is considered to be an endogenous potential, as its occurrence links not to the physical attributes of a stimulus, but to a person’s reaction to it. More specifically, the P300 is thought to reflect processes involved in stimulus evaluation or categorization. It is usually elicited using the oddball paradigm, in which low-probability target items are mixed with high-probability nontarget (or “standard”) items .
The P300 response occurs at around 300 ms in the oddball paradigm, for example, regardless of the type of stimulus presented: visual, tactile, auditory, olfactory, and gustatory.
Because of this general invariance with regard to stimulus type, the P300 component is understood to reflect a higher cognitive response to unexpected and/or cognitively salient stimuli .