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Measurements of impulsive and premeditated aggression, developed recently, have been applied to prison and outpatient populations without severe mental disorders. Comparable measures of impulsive and premeditated aggression have not been developed for populations with a severe mental disorder. A practical difficulty is that seriously disturbed, thought-disordered patients are incapable of providing reliable historical information. The investigators adapted the Barratt-Stanford instrument for differentiating impulsive from premeditated aggression so that instead of serving as an interview schedule, it could be used to assess aggression from previously documented written descriptions. The study found that the majority of ratable patients showed predominantly impulsive aggression, and after omitting four weak items, the inter-rater reliability for the determination of impulsive aggression was good (k = 0.53). Far fewer of the patients were determined to have shown predominantly premeditated aggression (from 14.2% to 15.5%) and the inter-rater reliability for premeditated aggression was deemed fair (k = 0.33).

To determine whether impulsivity was related to severity of drug use and treatment outcome, 50 cocaine dependent subjects underwent baseline measures of severity of current cocaine use and the Barratt Impulsiveness Scale (BIS-11). The hypothesis of the study was that there would be a significant correlation between impulsivity and cocaine use severity. As predicted, there was a significant correlation between BIS-11 total scores and self-reported average daily cocaine use as well as cocaine withdrawal symptoms. A subset of 35 patients underwent a 12-week double-blind placebo controlled trial of buspirone and group therapy. Subjects with high baseline impulsivity remained in the study a significantly shorter period than did subjects with lower baseline impulsivity. This study shows that impulsivity is a significant predictor of cocaine use and treatment retention, and suggests the need for targeting impulsivity in cocaine dependence treatment.

To assess the psychometric properties of the Italian translation of the Barratt Impulsiveness Scale-11 (BIS-11), the scale was administered to 763 college undergraduates. Based on analyses using item-total correlations and t-tests for differences between the top and the bottom total score quartiles, all items from the English version of the BIS-11 were retained in the Italian version. Cronbach's alpha for internal consistency was.79 and two-month test-retest reliability was.89. An exploratory principal-components analysis replicated the six first-order factors and three oblique second-order factors, consistent with the number identified in the English version. However, subfactor item loadings differed between the English and Italian versions. The overall item pool was consistent in being a homogeneous measure of impulsiveness. The BIS-11 total score was correlated significantly with aggression and ADHD measures. The BIS-11 also significantly differentiated between high and low levels of binge eating, alcohol consumption, and cigarette smoking.

Although aggression research in general has been hampered by a lack of objective measurements of aggressive acts, two types of aggressive acts, impulsive vs. premeditated, have been studied extensively in recent years. These two types of aggression have been primarily measured by structured or semi-structured interviews. The current study was designed to assess the construct validity of these two types of aggression using a self-report questionnaire which included items gleaned from the content of interviews used in past studies. For this study, 216 college students assessed their own aggressive acts rather than answering general questions about aggression. The students were not significantly different from normative sample groups on self-report measures of impulsiveness, aggression, and anger/hostility. A PCA factor analysis with a promax rotation of the items on the self-report questionnaire identified four factors: impulsive aggression; mood on the day the act occurred; premeditated aggression; and agitation. Thus, impulsive and premeditated aggression are independent constructs which exist in varying degrees among these 'normal' persons in a non-clinical sample. Impulsive aggression was characterized in part by feelings of remorse following the acts and by thought confusion. Premeditated aggression was related to social gain and dominance.

Studies of the effects of phenytoin on aggression have produced equivocal results primarily because of a lack of (1) common objective criterion measures of aggressive acts across studies; (2) rigorous inclusion and exclusion criteria for selecting subjects; and (3) a nosologic basis for classifying different types of aggression. The current study was designed to remedy these deficiencies. Aggression was defined using a nosology that defines three types of aggression: (1) medically related; (2) premeditated; and (3) impulsive. The purpose of this study was to test the hypothesis that phenytoin will decrease impulsive aggressive acts but not have a significant influence on premeditated aggressive acts. Sixty inmates were divided into two groups on the basis of committing primarily impulsive aggressive acts or premeditated aggressive acts while in prison. Medical aggression was ruled-out by subject selection. The study used a double-blind, placebo-controlled, crossover design. As hypothesized, phenytoin (200 mg a.m. and 100 mg p.m.) significantly reduced impulsive aggressive acts but not premeditated aggressive acts. Event-related potentials (ERPs) measured information processing in the cortex during drug/placebo conditions. The amplitudes of P300 ERP waveforms among impulsive aggressive subjects were increased significantly during the phenytoin condition but not during the placebo condition. There were no significant changes in P300 ERP waveforms between drug/placebo conditions among nonimpulsive aggressive subjects.

The purpose of this study was to test whether subjects who commit impulsive vs non-impulsive aggression differ on measurements of personality, neuropsychology, and cognitive psychophysiology, and whether these differences can yield information regarding the etiology of impulsive aggression. Subjects were two groups of prison inmates, distinguished by their committal of impulsive or nonimpulsive aggression, and matched noninmate controls. All inmates met DSM III-R criteria for an antisocial personality disorder but for no other disorder. Impulsiveness, anger, and peak P300 latencies did not differ between the inmate groups, but verbal symbol decoding and peak P300 amplitudes did. Impulsiveness and verbal skills were inversely correlated. Impulsiveness was inversely correlated with, and verbal skills positively correlated with P300 amplitudes. The results indicate that aggression is not homogenous, even among antisocial persons, and that impulsive aggression is related to neuropsychological and cognitive psychophysiological measures of information processing beyond those factors related to criminality alone.

The purpose of the present study was to revise the Barratt Impulsiveness Scale Version 10 (BIS-10), identify the factor structure of the items among normals, and compare their scores on the revised form (BIS-11) with psychiatric inpatients and prison inmates. The scale was administered to 412 college undergraduates, 248 psychiatric inpatients, and 73 male prison inmates. Exploratory principal components analysis of the items identified six primary factors and three second-order factors. The three second-order factors were labeled Attentional Impulsiveness, Motor Impulsiveness, and Nonplanning Impulsiveness. Two of the three second-order factors identified in the BIS-11 were consistent with those proposed by Barratt (1985), but no cognitive impulsiveness component was identified per se. The results of the present study suggest that the total score of the BIS-11 is an internally consistent measure of impulsiveness and has potential clinical utility for measuring impulsiveness among selected patient and inmate populations.

Blood platelet uptake of 3H-serotonin (5HT uptake), a potential marker of serotonergic function, was determined in male outpatients with episodic aggression (n = 15) and in age- and sex-matched nonaggressive controls (n = 15). Correlations with rating scales of "impulsivity" (Barratt Impulsivity Scale, 10th revision) and "anger" (Spielberger Anger Expression Scale) were performed. Mean 5HT uptake was 18% lower in patients with episodic aggression. A significant negative correlation between % difference in platelet 5HT uptake and impulsivity score was observed, but the correlation between 5HT uptake and anger was not significant. These results support the hypothesis of disturbed serotonergic function in aggression and suggest that the primary relationship is in the "control" of aggression. The blood platelet may be useful in identifying impulsive subtypes.