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PubMed2003

Serum cholesterol and impulsivity in a large sample of healthy young men.

Studies that have investigated the association between cholesterol levels and impulsivity are relatively few in number and have yielded equivocal results. In this study, we investigated the relationship between impulsivity, depression and serum lipids [total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides] in a large sample (N=2051) of healthy young men who were remarkably homogeneous in terms of age, educational level, and socioeconomic conditions. Depression was assessed using the depression scale of the Minnesota Multiphasic Personality Inventory-2, and impulsivity was measured using the impulse control scale of the Big Five Questionnaire (BFQ). We found that subjects with a low serum cholesterol, defined as the lowest tenth of the total cholesterol distribution (< or =3.7 mmol/l), scored significantly lower on the impulse control scale of the BFQ. There was no significant association between depression and cholesterol concentrations. In addition, in a multiple regression model, both lower levels of total cholesterol and higher levels of HDL cholesterol emerged as significant predictors of impulsivity. However, since the regression model accounted for only 0.6% of the variance in the score on the impulse control scale of the BFQ, the biological significance of these correlations was negligible. Taken together, these findings suggest that, in healthy young men, a relationship between cholesterol and impulsivity emerges only when the statistical analysis focuses on subjects with very low levels of cholesterol.

Adult↗

PubMed2001

Self-report vs. computerized measures of impulsivity as a correlate of suicidal behavior.

OBJECTIVES: To compare the use of a self-report form of impulsivity versus a computerized test of impulsivity in the assessment of suicidal adolescent psychiatric inpatients. METHODS: Sixty consecutive admissions to an adolescent in patient unit were examined. The severity of suicidal behavior was measured with the Childhood Suicide Potential Scale (CSPS), and impulse control was measured with the self report Plutchik Impulse Control Scale (ICS) and with the Test of Variables of Attention (TOVA), a continuous performance test (CPT). The TOVA is used to diagnose adolescents with attention deficit disorder. RESULTS: There was a significant but low correlation between the two measures of impulsivity. Only the TOVA commission and omission errors differentiated between adolescent suicide attempters and nonattempters. CONCLUSIONS: Computerized measures of impulsivity may be a useful way to measure impulsivity in adolescent suicide attempters. Impulsivity appears to play a small role only in nondepressed suicidal adolescents, especially boys.

Adolescent↗

PubMed1998

Increased impulsivity after injected alcohol predicts later alcohol consumption in rats: evidence for "loss-of-control drinking" and marked individual differences.

A delay-of-reward paradigm was used to assess impulsivity in rats. Previous research with this paradigm has found that normally occurring impulsivity scores predict magnitude of voluntary alcohol intake. The authors' primary findings were (a) injected alcohol produced a dose-dependent increase in impulsivity, (b) varying the intervals between alcohol and testing yielded orderly effects, (c) there were extreme individual differences in impulsive reactivity to alcohol, (d) these individual differences did not reflect differences in alcohol pharmacokinetics, (e) subject selection procedures ensured that differences in impulsive reactivity to alcohol were independent of significant variations in baseline impulsivity scores, and (f) individual differences in impulsive reactivity to injected alcohol strongly predicted magnitude of voluntary alcohol intake. The findings are discussed in terms of evidence for a dysfunctional alcohol-induced positive feedback loop ("loss-of-control drinking"), alcohol disinhibition, and the relationship between impulse control and the regulation of alcohol consumption.

Alcohol Drinking↗

PubMed1997

Does the repeated gambles procedure measure impulsivity in social drinkers.

P. Sarfati and K. G. White (1991) found that heavy social drinkers were more risk averse than light drinkers in a repeated gambles procedure. Given a theoretical argument that risk aversion corresponds to impulsivity in this context, this result implied that heavy drinkers are more impulsive than light drinkers. The present study sought to replicate this finding, and, by administering questionnaire measures of impulsivity, to explore the relation between drinking and impulsivity as measured by the repeated gambles procedure and impulsivity as measured by questionnaires. Results showed more impulsivity among heavy drinkers than light drinkers on the questionnaires but not on choices during the repeated gambles procedure. These results question the utility of the repeated gambles procedure as a measure of impulsivity and as a useful vehicle for studying the drinking-impulsivity relation.

Adult↗

PubMed2003

Effects of THC on behavioral measures of impulsivity in humans.

This study investigated the acute effects of delta(9)-tetrahydrocannabinol (THC) on four behavioral measures of impulsivity in recreational marijuana users. Although impulsive behavior has been studied using several different measures of impulsivity, few studies have utilized more than one of these measures on a single cohort. In this study, 37 healthy men and women participated in three sessions, in which they received capsules containing placebo, 7.5, or 15 mg THC in randomized order under double-blind conditions. Subjects were tested on the following four tasks: the Stop task, which measures the ability to inhibit a prepotent motor response; a Go/no-go task; a Delay discounting task, which measures the value of delayed or uncertain reinforcers; and a time estimation task, which measures alterations in time perception through a time reproduction procedure. Subjects also completed mood questionnaires and general measures of performance. THC produced its expected effects on subjective measures including increases in ARCI euphoria and marijuana scales. THC increased impulsive responding on the Stop task but did not affect performance on either the Go/no-go or Delay or Probability discounting tasks. On the time reproduction task, THC increased estimates of the duration of short intervals while not affecting estimates of longer intervals. There were no significant correlations between the four tasks either before or after drug administration. These results suggest that THC may increase certain forms of impulsive behavior while not affecting other impulsive behaviors. The dissociations between the four measures of impulsivity suggest that impulsivity is an assemblage of distinct components rather than a unitary process.

Adolescent↗

PubMed2006

Acute effects of 3,4-methylenedioxymethamphetamine (MDMA) on behavioral measures of impulsivity: alone and in combination with alcohol.

The use of 3,4-methylenedioxymethamphetamine (MDMA) has frequently been associated with increased levels of impulsivity during abstinence. The effects of MDMA on measures of impulsivity, however, have not yet been studied during intoxication. The present study was designed to assess the acute effects of MDMA and alcohol, alone and in combination, on behavioral measures of impulsivity and risk-taking behavior. A total of 18 recreational users of MDMA entered a double-blind placebo-controlled six-way crossover study. The treatments consisted of MDMA 0, 75, and 100 mg with and without alcohol. Alcohol dosing was designed to achieve a peak blood alcohol concentration (BAC) of about 0.06 g/dl during laboratory testing. Laboratory tests of impulsivity were conducted between 1.5 and 2 h post-MDMA and included a stop-signal task, a go/no-go task, and the Iowa gambling task. MDMA decreased stop reaction time in the stop-signal task indicating increased impulse control. Alcohol increased the proportion of commission errors in the stop-signal task and the go/no-go task. Signal detection analyses of alcohol-induced commission errors indicated that this effect may reflect impairment of perceptual or attentive processing rather than an increase of motor impulsivity per se. Performance in the Iowa gambling task was not affected by MDMA and alcohol, but there was a nonsignificant tendency towards improvement following alcohol intake. None of the behavioral measures of impulsivity showed a MDMA x alcohol interaction effect. The lack of interaction indicated that the CNS stimulant effects of MDMA were never sufficient to overcome alcohol-induced impairment of impulse control or risk-taking behavior.

Acute Disease↗

PubMed2004

Impulsivity and smoking relapse.

Previous research has shown that elevated trait-impulsivity heightens the risk for initiating tobacco use and indicates that nicotine may be disproportionately rewarding for more impulsive persons. However, the influence of impulsivity on the ability to maintain nicotine abstinence has not been studied. The present study tested the hypothesis that a higher level of trait-impulsivity would predict a more rapid relapse to smoking following 48 hr of nicotine abstinence. Participants were euthymic, regular smokers (N=45), with a history of at least one major depressive episode, who participated in a paid smoking cessation study with biological challenge (tryptophan depletion). Treatment involved a 1-day skills training workshop followed by 48 hr of bioverified abstinence and weekly follow-up for 1 month. Regression analyses indicated that elevated impulsivity predicted shorter time to relapse following the workshop after controlling for treatment condition, baseline nicotine dependence, and age (beta=-.39, R(2) change=.147, p=.011). Greater impulsivity predicted more rapid relapse to smoking, which mediational analyses indicated could not be explained by positive affect, negative affect, or craving. Findings suggest a need to identify alternative mechanisms to explain impulsive smokers' increased difficulty in maintaining abstinence and to develop targeted treatments that address the special needs of smokers high in impulsivity.

Adolescent↗

PubMed2005

Dopamine, learning, and impulsivity: a biological account of attention-deficit/hyperactivity disorder.

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) affects up to 10% of school-age children. The impulsivity which is seen as its core feature persists over years, yet experimental measures of impulsivity can be altered in a single session. In this study, we tested the theory that both the persistence and the variability of impulsivity could be the result of abnormalities in learning mechanisms and environment. METHOD: We extended an existing model of the role of dopamine in operant conditioning to address the delayed response time task, which is one of the standard tests for impulsivity in ADHD. In this task, subjects choose between immediate responding for a small reinforcer and later responding for a larger one. We studied the influence on impulsivity of four key parameters of the model: The learning rate, discount factor, brittleness, and action bias. RESULTS: The behavior of the model is broadly comparable with electrophysiological (monkey) and behavioral (ADHD and normal) data. Variations in any of the parameters can cause impulsivity. All parameters except the discount factor show inverted U-shaped curves for their effects on impulsivity, suggesting, for example, how either hyper- or hypofunctioning of dopamine can cause impulsivity. The model suggests how decision making can be affected by environmental unpredictability, and thus offers an account of one aspect of the natural history of ADHD. CONCLUSIONS: Some types of ADHD may be caused by specific deficits in reinforcement learning and in the use of learned lessons. Environmental factors can interact with these deficits to delay maturation.

Attention Deficit Disorder with Hyperactivity↗

PubMed2004

Impulsivity, time perception, emotion and reinforcement sensitivity in patients with orbitofrontal cortex lesions.

Damage to the orbitofrontal cortex (OFC) in humans has been associated with disinhibited or socially inappropriate behaviour and emotional changes. Some of the changes may be related to difficulty in responding correctly to rewards and punishers, in that these patients have difficulty in learning to correct their choice of a visual stimulus when it is no longer associated with reward. We extend this fundamental approach by investigating the relationship between frontal dysfunction and impulsive behaviour, the behavioural, emotional and personality changes seen in patients with prefrontal cortex damage, and thus in addition illuminate the cognitive and biological processes that are impaired in impulsive people. OFC patients (n = 23) performed more impulsively on both self-report and cognitive/behavioural tests of impulsivity, reported more inappropriate 'frontal' behaviours, and performed worse on a stimulus-reinforcement association reversal task, than non-OFC prefrontal cortex lesion control (n = 20) and normal control (n = 39) participants. Further, OFC patients experienced more subjective anger than non-OFC and normal participants, and less subjective happiness than normals; and had a faster subjective sense of time (overestimated and underproduced time intervals) than normal controls, while non-OFC patients did not differ from normals. Finally, both OFC and non-OFC patients were less open to experience than normal participants. There were no differences between OFC patients, non-OFC lesion patients and normal controls on all other personality traits, most notably extraversion. In a spatial working memory task, the non-OFC group, most of whom had dorsolateral prefrontal cortex lesions, were impaired in that they repeatedly returned to previously chosen empty locations ('within errors'), whereas OFC patients were not impaired on this measure. Thus there is a dissociation between the effects of OFC damage which does not affect this measure of spatial working memory but does affect impulsive and inappropriate behaviour, reversal, personality, time perception and emotion; and dorsolateral prefrontal cortex damage which does affect this measure of spatial working memory, but not impulsive and inappropriate behaviour, reversal, personality, time perception and emotion. The effects of OFC damage on impulsive and related behaviours described here have implications for understanding impulsive behaviour.

Adolescent↗

PubMed2005

Effects of acute and chronic nicotine on impulsive choice in rats.

Impulsive choice, or preference for small immediate reinforcers over large delayed reinforcers, has been associated with cigarette smoking. The direct effects of nicotine on impulsive choice in laboratory animals are unknown. We examined the effects of acute and chronic nicotine injections, and the termination of injections, on impulsive choice in rats. Five rats made choices between a one- and a three-pellet reinforcer in a discrete trials procedure. The delay to the smaller reinforcer was always 1 s. A computer adjusted the delay to the larger reinforcer until the pattern of choices reflected indifference between the two alternatives. We assessed the effects of acute and chronic nicotine (vehicle, 0.03, 0.1, 0.3 and 1.0 mg/kg nicotine). The latency to make the first response of the session increased under the acute 1.0 mg/kg dose. There were no consistent differences in the effects of acute and chronic nicotine on response latency and lever pressing during the delays between choices. Acute injections of nicotine dose-dependently increased impulsive responding. After chronic injections, impulsive responding was increased equivalently regardless of dose, and it was increased even in the absence of nicotine. After drug injections were terminated, behavior remained impulsive for about 30 drug-free sessions, and then responding gradually returned to baseline levels. The results suggest that increases in impulsive choice were not due to anorectic effects, response biases or changes in conditioned reinforcement. Nicotine may have decreased the value of delayed reinforcers. Chronic nicotine exposure produced long-lasting but reversible increases in impulsive choice.

Animals↗

PubMed2006

Impulsivity in abstinent early- and late-onset alcoholics: differences in self-report measures and a discounting task.

AIMS: To test the hypothesis that early-onset alcoholics (EOAs) can be differentiated from late-onset alcoholics (LOAs) by more severe substance-related problems and higher levels of impulsivity and aggression. DESIGN AND MEASUREMENTS: A cross-sectional patient survey with a community comparison group. The European Addiction Severity Index was used to assess substance-related problems and the Barratt Impulsiveness Scale, the Dutch version of the Zuckermann Sensation Seeking Scale and the Buss-Durkee Hostility Inventory were used to assess impulsive and aggressive traits. Impulsive decision making was assessed using a delay discounting task (DDT) with hypothetical monetary rewards. PARTICIPANTS AND SETTING: Participants were EOAs (n = 42) and LOAs (n = 46) recruited from an addiction treatment centre and an unmatched, non-substance-abusing comparison group (n = 54). Findings The EOAs had higher levels of impulsive decision making than both the LOAs and the comparison group. The EOAs had higher scores than the LOAs on measures of impulsiveness, aggressiveness and the severity of substance-related problems. CONCLUSIONS: This study provides evidence that EOAs are more impulsive and aggressive than LOAs. Further identification of alcoholism subtypes based on dimensions of impulsivity should be considered in the light of their relationship with pharmacological and behavioural treatment interventions.

Adult↗

PubMed2007

Reduced frontal lobe activity in subjects with high impulsivity and alcoholism.

OBJECTIVE: Impulsivity is an important characteristic of many psychiatric disorders, including substance-related disorders. These disinhibitory disorders have a similar underlying genetic diathesis, with each disorder representing a different expression of the same underlying genetic liability. This study assessed whether there is a relationship between impulsivity and alcohol dependence, and their correlations with P3 (P300) amplitude, a proposed endophenotype of alcoholism. METHODS: Healthy control subjects (n=58) and subjects with DSM-IV diagnosis of alcohol dependence (n=57) were assessed with a visual oddball task. Event-Related Potentials (ERPs) were recorded from 61 scalp electrodes and P3 amplitudes measured. Barratt Impulsiveness Scale (BIS), version 11, was used to evaluate impulsivity. Source localization of P3 was computed using low-resolution brain electromagnetic tomography (LORETA). RESULTS: Alcoholic subjects manifested reductions in target P3 amplitudes (p<0.0001). Using LORETA, significantly reduced activation was mapped in the cingulate, medial, and superior frontal regions in alcoholic subjects and highly impulsive subjects. Alcoholic subjects had significantly higher scores on the BIS (p<0.0001) than nonalcoholic individuals. There were significant negative correlations between total scores on BIS and P3 amplitude (r=-0.274, p=0.003, on Pz; r=-0.250, p=0.007, on Cz). CONCLUSIONS: Our results demonstrate a strong frontal focus of reduced activation during processing of visual targets in alcoholic subjects and individuals with higher impulsivity. The findings suggest that impulsivity may be an important factor that underlies the pathogenesis of alcohol dependence. Studies are underway to examine the relationship between impulsivity and ERPs in offspring of alcoholic subjects, and to identify genes associated with the underlying predisposition involved in disinhibitory disorders.

Adult↗

PubMed2001

The relationship of childhood abuse to impulsivity and suicidal behavior in adults with major depression.

OBJECTIVE: This study investigated whether a higher frequency of reported childhood trauma would be found in depressed adults with higher levels of trait impulsivity, aggression, and suicidal behavior. METHOD: In 136 depressed adult inpatients, the authors assessed trait impulsivity, aggression history, and number of lifetime suicide attempts as well as the medical lethality and the intent to die associated with the most lethal attempt. These variables were then compared between those with and those without a reported history of childhood physical or sexual abuse. RESULTS: Subjects who reported an abuse history were more likely to have made a suicide attempt and had significantly higher impulsivity and aggression scores than those who did not report an abuse history. Impulsivity and aggression scores were significantly higher in subjects with a history of at least one suicide attempt. A logistic regression analysis revealed that abuse history remained significantly associated with suicide attempt status after adjustment for impulsivity, aggression history, and presence of borderline personality disorder. Among those who attempted suicide, there were no significant differences in severity of suicidal behavior between those with and without a childhood history of abuse. CONCLUSIONS: Abuse in childhood may constitute an environmental risk factor for the development of trait impulsivity and aggression as well as suicide attempts in depressed adults. Alternatively, impulsivity and aggression may be inherited traits underlying both childhood abuse and suicidal behavior in adulthood disorders. Additional research is needed to estimate the relative contributions of heredity and environmental experience to the development of impulsivity, aggression, and suicidal behavior.

Adult↗

PubMed2005

Impact of trait impulsivity and state aggression on divalproex versus placebo response in borderline personality disorder.

OBJECTIVE: The authors' goal was to determine whether specific pretreatment clinical characteristics differentially predict favorable treatment response to divalproex versus placebo for impulsive aggression in patients with borderline personality disorder. METHOD: Fifty-two outpatients with DSM-IV borderline personality disorder were randomly assigned to receive divalproex (N=20) or placebo (N=32), double-blind, for 12 weeks. Trait impulsivity symptoms were determined by using the Barratt Impulsiveness Scale, and state aggression symptoms were determined by using the Overt Aggression Scale modified for outpatients. Affective stability was determined by using the Young Mania Rating Scale and the Hamilton Depression Rating Scale. Analyses were performed to identify possible baseline symptom domains that predict treatment response. RESULTS: Divalproex was superior to placebo in reducing impulsive aggression in patients with borderline personality disorder. Divalproex-treated patients responded better than placebo-treated patients among those with higher baseline trait impulsivity symptoms and state aggression symptoms. The effects of baseline trait impulsivity and state aggression appear to be independent of one another. However, baseline affective instability did not influence differential treatment response. CONCLUSIONS: Both pretreatment trait impulsivity symptoms and state aggression symptoms predict a favorable response to divalproex relative to placebo for impulsive aggression in patients with borderline personality disorder.

Adult↗

PubMedDate not supplied

Impulsive-aggressive traits and suicidal adolescents and young adults with alcoholism.

Suicidal behavior and alcohol use disorders among adolescents and young adults are serious public health problems. In the study of suicidal behavior among young people with alcoholism, it has been shown that aggression and impulsivity are higher among those who attempted suicide. Impulsivity has been related to suicidal and self-destructive behaviors within different psychiatric conditions, i.e. alcohol and substance use disorders, mood disorders, conduct disorder, impulse control disorders, antisocial personality disorder, and borderline personality disorder. The term impulsivity has been used to define different constructs such as (1) personality trait or cognitive style in which disinhibition is the core characteristic, (2) a tendency to act immediately in response to external or internal stimuli, and (3) a group of psychiatric disorders with behavioral dyscontrol. Among adolescents suicidal behavior is transmitted in families independently of psychiatric conditions, but not independently of impulsivity/aggression. Two causal links between impulsiveness and alcoholism have been proposed: (1) adolescents who develop alcoholism possess higher premorbid levels of impulsiveness than those who do not develop alcoholism, and (2) levels of impulsiveness differentiate both populations only after the development of alcoholism, with higher levels of impulsiveness among those adolescents who developed alcoholism. Cognitive behavioral techniques have shown promising results in the treatment of adolescents with alcohol and substance use disorder and suicidality. The relative frequency of suicidal behavior among adolescents and young adults suffering from alcoholism and its subsequent devastating effects on individuals, families and society merits further research and development of prevention strategies.

Adolescent↗

PubMed2005

[Impulsivity and mental disorders].

OBJECTIVE: Although there are several studies revealing the role of impulsivity in mental disorders, debates in the literature about how to define and determine impulsivity continue. Being a measurable feature of behaviour, impulsivity is defined as the failure to resist a drive or stimulus or as a personality dimension as the inability to resist the desire to harm one's self or others. Besides this negative definition, however, impulsivity is also defined as independent dysfunctional and functional concepts having both positive and negative consequences. It can be a psychopathological structural part of many mental disorders, but it can be a characteristic of normal behaviour as well. Although not defined in detail in DSM-IV, it is mentioned as a diagnostic criterion in several mental disorders like impulse control disorders (pathological gambling, intermittent explosive disorder, pyromania, kleptomania and trichotillomania), impulsive aggressive disorders of personality (borderline, antisocial, histrionic and narcissistic), manic episodes of bipolar disorder, attention deficit hyperactivity disorder (ADHD), neurological disorders with behavioural disinhibition and substance abuse. Studies have revealed impulsivity to be more common in subjects with conduct disorders, attention deficit hyperactivity disorder, disorders of personality, substance and alcohol abuse, psychotic disorders, bipolar disorders, eating disorders and dementia compared to healthy subjects in control groups. The aim of the present paper is to define impulsivity as a concept and symptom, to discuss its relation to mental disorders, to show the biological basis of this relationship and to review the literature relating to this issue.

Female↗

PubMed1986

The role of defensiveness in cognitive impulsivity.

The role of anxiety in reflection-impulsivity has been a source of controversy, with impulsives portrayed as unanxious by some researchers and as extremely anxious by others. Defensiveness may account for these seemingly contradictory results. Impulsives may present a facade of unconcern to mask underlying anxiety. The impulsive response itself may occur in part because impulsives are defensive about appearing incompetent. Equating rapidity of response with competence, they respond quickly to appear competent. 120 children, with a mean age of 9 years, 7 months, served as subjects. Measurements of defensiveness and impulsivity were examined. Correlations were examined separately by sex since previous research showed that defensiveness correlated negatively with problem-solving success for boys only. Defensiveness and impulsivity were positively correlated for boys only. Unlike previous studies, test anxiety correlated positively with impulsivity for girls.

Anxiety↗

PubMed1991

The distribution of the intervals between neural impulses in the maintained discharges of retinal ganglion cells.

Simulated neural impulse trains were generated by a digital realization of the integrate-and-fire model. The variability in these impulse trains had as its origin a random noise of specified distribution. Three different distributions were used: the normal (Gaussian) distribution (no skew, normokurtic), a first-order gamma distribution (positive skew, leptokurtic), and a uniform distribution (no skew, platykurtic). Despite these differences in the distribution of the variability, the distributions of the intervals between impulses were nearly indistinguishable. These inter-impulse distributions were better fit with a hyperbolic gamma distribution than a hyperbolic normal distribution, although one might expect a better approximation for normally distributed inverse intervals. Consideration of why the inter-impulse distribution is independent of the distribution of the causative noise suggests two putative interval distributions that do not depend on the assumed noise distribution: the log normal distribution, which is predicated on the assumption that long intervals occur with the joint probability of small input values, and the random walk equation, which is the diffusion equation applied to a random walk model of the impulse generating process. Either of these equations provides a more satisfactory fit to the simulated impulse trains than the hyperbolic normal or hyperbolic gamma distributions. These equations also provide better fits to impulse trains derived from the maintained discharges of ganglion cells in the retinae of cats or goldfish. It is noted that both equations are free from the constraint that the coefficient of variation (CV) have a maximum of unity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗