Trait impulsivity in patients with mood disorders.

BACKGROUND: Impulsivity is a key component of the manic behavior of bipolar disorder and is reported to occur in bipolar patients as a stable characteristic, i.e. a trait. Nevertheless, impulsivity has not been widely studied in depressed bipolar patients. We assessed impulsivity in depressed and euthymic bipolar and unipolar patients and healthy controls. We hypothesized that bipolar subjects would have higher levels of trait impulsivity than the comparison groups. METHODS: Twenty-four depressed bipolar, 24 depressed unipolar, 12 euthymic bipolar, and 10 euthymic unipolar patients, as well as 51 healthy subjects were evaluated with the Barratt Impulsiveness Scale (BIS). Analysis of covariance with age and sex as covariates was used to compare mean group differences. RESULTS: Depressed bipolar, euthymic bipolar, and depressed unipolar patients did not differ, and showed greater impulsivity than healthy controls on all of the BIS scales. Euthymic unipolar patients scored higher than healthy controls only on motor impulsivity. LIMITATIONS: Higher number of past substance abusers in the bipolar groups, and no control for anxiety and personality disorders, as well as small sample sizes, limit the reach of this study. CONCLUSIONS: This study replicates prior findings of stable trait impulsivity in bipolar disorder patients, and extends them, confirming that this trait can be demonstrated in depressed patients, as well as manic and euthymic ones. Trait impulsivity may be the result of repeated mood episodes or be present prior to their onset, either way it would influence the clinical presentation of bipolar disorder.

Examination of an altered bar code on a vehicle tax disc.

Altered vehicle excise licences (tax discs) are regularly submitted for questioned document examination in order to reveal the original vehicle details. A bar code printed on tax discs permits the electronic storage and transfer of vehicle licensing information. In a recent case involving a tax disc on which the printed serial number had been partially removed, it was possible to restore and manually decode an obliterated bar code. This allowed recovery of the complete serial number of the disc and subsequent retrieval of the original entries.

Effect of chronic marijuana administration of stages of primate sleep-wakefulness.

The effects of the repeated administration of delta-9-tetrahydrocannabinol on sleep-wakefulness patterns were studied in adult male squirrel monkeys. The percent time spent in slow wave sleep was reduced with chronic treatment and failed to return to base line levels after 30 days of recovery. The amount of time spent in Stage 1 or drowsy state increased with repeated treatment and remained elevated through recovery. Changes observed in other stages of sleep-wakefulness were sensitive to repeated treatment with marijuana but were found to return to base line levels during recovery.

Neuropsychological and cognitive psychophysiological substrates of impulsive aggression.

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.

Psychiatric aspects of impulsivity.

OBJECTIVE: The authors discuss the relationship of impulsivity to psychiatric disorders and present selected hypotheses regarding the reasons for these relationships. METHOD: Previous research has shown significantly higher levels of impulsivity among patients with conduct disorder, personality disorders, substance use disorders, and bipolar disorder, compared to other psychiatric patients or healthy comparison subjects. A literature review of the theoretical bases of the relationship between these disorders and impulsivity is presented. Measurements of impulsivity and treatment options are discussed in relation to the physiology of impulsivity and the disorders in which it is a prominent feature. RESULTS: Impulsivity, as defined on the basis of a biopsychosocial approach, is a key feature of several psychiatric disorders. Behavioral and pharmacological interventions that are effective for treating impulsivity should be incorporated into treatment plans for these disorders. CONCLUSIONS: The high comorbidity of impulsivity and selected psychiatric disorders, including personality disorders, substance use disorders, and bipolar disorder, is in a large part related to the association between impulsivity and the biological substrates of these disorders. Before treatment studies on impulsivity can move forward, measures of impulsivity that capture the core aspects of this behavior need to be refined and tested on the basis of an ideologically neutral model of impulsivity.

Can skull morphology be used to predict ecological relationships between bat species? A test using two cryptic species of pipistrelle.

Can ecological relationships between bat species be predicted largely on the basis of morphology? This question was addressed by investigating skull morphology of two cryptic species of the pipistrelle bat. Since 45 Pipistrellus pipistrellus apparently eats larger prey than 55 P. pipistrellus, we predicted that it would have a larger overall skull size, a larger dentary apparatus, and a larger gape. To test these predictions, variables were measured from skulls of the two cryptic species, and comparisons made between them. In accordance with our predictions, overall skull size was larger in 45 P. pipistrellus than in 55 P. pipistrellus, and 45 P. pipistrellus had a longer lower jaw and the distance between the jaws at maximum gape was larger. In addition, 45 P. pipistrellus had longer upper canines, which may allow it to pierce harder prey items than 55 P. pipistrellus. Only some aspects of dietary differences between the two cryptic species could be explained by differences in skull morphology, and we suggest that empirical data, at least on diet and habitat use, are also required to explain mechanisms of resource partitioning among species in bat communities.

Parentage, reproductive success and breeding behaviour in the greater horseshoe bat (Rhinolophus ferrumequinum).

Female greater horseshoe bats form maternity colonies each summer in order to give birth and raise young. During the mating period, females visit males occupying territorial sites, copulation takes place and sperm are stored until ovulation occurs, normally in April. Using microsatellite markers and a likelihood method of parentage analysis, we studied breeding behaviour and male reproductive success over a five-year period in a population of bats in south-west Britain. Paternity was assigned with 80% confidence to 44% of young born in five successive cohorts. While a small annual skew in male reproductive success was detected, the variance increased over five years due to the repeated success of a few individuals. Mating was polygynous, although some females gave birth to offspring sired by the same male in separate years. Such repeated partnerships probably result from fidelity for either mating sites or individuals or from sperm competition. Females mated with males born both within and outside their own natal colony; however, relatedness between parents was no less than the average recorded for male female pairs. Gene flow between colonies is likely to be primarily mediated by both female and male dispersal during the mating period rather than more permanent movements.

Outbreeding increases offspring survival in wild greater horseshoe bats (Rhinolophus ferrumequinum).

The factors influencing the survival of greater horseshoe bat (Rhinolophus ferrumequinum) offspring born over seven years at a maternity colony in south-west Britain were studied. The effects of a range of phenotypic and maternal variables were analysed using a historical data set. In addition, the influence of two genetic measures on mortality, individual heterozygosity and a new measure of outbreeding, termed mean d(2), was assessed. Logistic regressions were undertaken with survival modelled as a binary response variable. Survival to two life stages was studied for each variable and all models were developed for both sexes separately and together. Only one variable, mean d(2), was significantly associated with survival. Male offspring with high mean d(2) scores were more likely to survive to their first and second summers. The influence of mean d(2) was not due to a single locus under selection but a wider multilocus effect and probably represents heterosis as opposed to solely inbreeding depression. Therefore, the extent to which an individual is outbred may determine survival more than widely used phenotypic characteristics such as size and mass. Mean d(2) may reflect immunocompetence, which influences mortality. Protection of mating sites in order to facilitate gene flow and, therefore, outbreeding may help to promote population stability and growth.

Effect of chronic pentobarbital treatment on the sleep patterns of squirrel monkeys.

Following a 30-day baseline, 60 days of sodium pentobarbital treatment (5 mg/kg) were given to squirrel monkeys 2 h prior to the start of a 12-h recording of EEG and EOG. Following the drug-treatment phase, an additional 30-day period was used to determine the rate of recovery. Repeated pentobarbital treatment significantly reduced awake time and slow wave sleep while it elevated the time spent in drowsy and light sleep. The recovery phase indicated a brief recovery of rapid eye movement sleep while the other stages failed to return to baseline levels. The cyclical nature of the changes observed with chronic pentobarbital suggest the importance of circadian fluctuations in the study of chronic drug treatment and the sleep-wakefulness process.

Impulsive and premeditated aggression: a factor analysis of self-reported acts.

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.

Blood platelet uptake of serotonin in episodic aggression.

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.

Effects of rapid depletion of phenylalanine and tyrosine on sleep and behavior.

The effects of fluctuations of free amino acid concentrations in plasma on sleep patterns and operant behavior in the squirrel monkey were studied. Plasma phenylalanine (PHE) and tyrosine (TYR) were rapidly lowered to trace levels within 4 hr by intraperitoneal administration of phenylalanine ammonia-lyase (PAL), an enzyme which specifically deaminates both PHE and TYR to inactivate products. Significant alterations in sleep patterns and in performance on a chained operant task involving hold and reaction time components were found, but no significant effect on the performance of a simple operant task was observed. Adminstration of saline or trans-p-cinnamic acid and trans-p-coumaric acid, the products of PHE and TYR deamination, produced no changes in behavior or sleep patterns. The reduction of plasma PHE and TYR resulted in a significant decrease in PHE and TYR levels in whole rat brain. Brain serotonin levels were increased within 4 hr after PAL administration, whereas, dopamine and norepinephrine levels were decreased subsequently (within 8 hr). These studies suggest that circulating levels of PHE and TYR are involved directly or indirectly in the modulation of certain parameters of brain function.

Individual differences in visual event-related potentials: P300 cognitive augmenting/reducing parallels N100 sensory augmenting/reducing.

In a visual event-related potential experiment, both N100 augmenting/reducing data and oddball paradigm P300 data were collected from the same subjects. A significant correlation was obtained between augmenting/reducing and the degree to which stimulus probability affected P300 amplitude. Subjects who augment/reduce in response to increased stimulus brightness in the sensory domain also appear to augment/reduce in response to low probability in the cognitive domain.

The impact of impulsivity on cocaine use and retention in treatment.

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.

Impulsivity and paced tapping.

The purpose of this study was to test the hypothesis that impulsivity is positively related to both the intraindividual variability and the rate of performance of a paced tapping task. The independent variable in the tapping task were: feedback vs. no feedback; tempo; concurrent cognitive task (counting) vs. no concurrent cognitive task. Three measures of tapping performance were computed: absolute or total error of tapping, tapping rate, and the intraindividual variability of tapping. The results confirm the hypothesis that impulsivity is positively related to rate of paced tapping, although the degree of relationship varied under different experimental conditions within the paced tapping task. Intraindividual variability of tapping was not significantly related to impulsivity, but the results were suggestive of a positive relationship.

The incompetent defendant: support systems help avoid future legal problems.

Reducing crime and improving efficiency of our criminal justice system should be facilitated by identifying how to treat and manage mental health patients who are prone to committing criminal acts more effectively. A total of 142 competency evaluations were reviewed from cases evaluated by the Galveston County Forensic Psychiatrist from 1984 to 1990. Examination of data from these defendants allowed us to address the psychiatric needs of these defendants in terms of contact with the mental health system, particularly those who had more than one criminal justice system contact. The latter defendants lacked social support systems and consistent mental health system follow-up to provide stabilization of their condition. It was felt that this was a factor in their more frequent contact with the criminal justice system.