Increased trait-like impulsivity and course of illness in bipolar disorder

Interacting mechanisms of impulsivity in bipolar disorder and antisocial personality disorder

BACKGROUND

Bipolar disorder and antisocial personality disorder (ASPD) overlap in clinical characteristics and behavioral consequences. Impulsivity is prominent in both, but there is little information on how specific mechanisms of impulsivity differentiate, bridge, or underlie the disorders.

METHODS

Subjects, all males, were controls (n = 46), bipolar disorder without cluster B personality disorder (n = 21), ASPD without bipolar disorder (n = 50), and bipolar disorder with ASPD (n = 16). Impulsivity measures were the Immediate Memory Task (IMT), a continuous performance test of response inhibition measuring ability to evaluate a stimulus before responding, and the Two-Choice Impulsivity Paradigm (TCIP), a choice between smaller-sooner and larger-later reward. Data were analyzed using general linear models analysis.

RESULTS

Subjects with bipolar disorder had fewer IMT correct detections and slower reaction times than controls. Reaction times were faster with combined diagnoses than in bipolar disorder alone. TCIP responding in either diagnosis alone resembled controls, but was more impulsive in combined disorders. These differences persisted after correction for age and education, which had significant independent effects. In combined ASPD and bipolar disorder, increased reaction speed, impulsive response bias, and reward-delay impulsivity occurred independent of substance-use disorder history.

CONCLUSIONS

Impulsivity was increased in the combined disorders over either disorder alone. Results were consistent with at least partially distinct mechanisms of impulsivity in ASPD and bipolar disorder. Compensatory mechanisms for impulsivity in uncomplicated ASPD or bipolar disorder appear to be compromised or lost when the disorders are combined.

Cognitions in bipolar affective disorder and unipolar depression: imagining suicide

OBJECTIVE

Bipolar disorder has the highest rate of suicide of all the psychiatric disorders. In unipolar depression, individuals report vivid, affect-laden images of suicide or the aftermath of death (flashforwards to suicide) during suicidal ideation but this phenomenon has not been explored in bipolar disorder. Therefore the authors investigated and compared imagery and verbal thoughts related to past suicidality in individuals with bipolar disorder (n = 20) and unipolar depression (n = 20).

METHODS

The study used a quasi-experimental comparative design. The Structured Clinical Interview for DSM-IV was used to confirm diagnoses. Quantitative and qualitative data were gathered through questionnaire measures (e.g., mood and trait imagery use). Individual interviews assessed suicidal cognitions in the form of (i) mental images and (ii) verbal thoughts.

RESULTS

All participants reported imagining flashforwards to suicide. Both groups reported greater preoccupation with these suicide-related images than with verbal thoughts about suicide. However, compared to the unipolar group, the bipolar group were significantly more preoccupied with flashforward imagery, rated this imagery as more compelling, and were more than twice as likely to report that the images made them want to take action to complete suicide. In addition, the bipolar group reported a greater trait propensity to use mental imagery in general.

CONCLUSIONS

Suicidal ideation needs to be better characterized, and mental imagery of suicide has been a neglected but potentially critical feature of suicidal ideation, particularly in bipolar disorder. Our findings suggest that flashforward imagery warrants further investigation for formal universal clinical assessment procedures.

Impaired goal-directed behavioural control in human impulsivity

Two dissociable learning processes underlie instrumental behaviour. Whereas goal-directed behaviour is controlled by knowledge of the consequences, habitual behaviour is elicited directly by antecedent Pavlovian stimuli without knowledge of the consequences. Predominance of habitual control is thought to underlie psychopathological conditions associated with corticostriatal abnormalities, such as impulsivity and drug dependence. To explore this claim, smokers were assessed for nicotine dependence, impulsivity, and capacity for goal-directed control over instrumental performance in an outcome devaluation procedure. Reduced goal-directed control was selectively associated with the Motor Impulsivity factor of Barrett's Impulsivity Scale (BIS), which reflects propensity for action without thought. These data support the claim that human impulsivity is marked by impaired use of causal knowledge to make adaptive decisions. The predominance of habit learning may play a role in psychopathological conditions that are associated with trait impulsivity.

Clinical and cognitive correlates of suicide attempts in bipolar disorder: is suicide predictable?

OBJECTIVE

We conducted a retrospective investigation of potential clinical, demographic, and neuropsychological risk factors for suicide attempts in patients diagnosed with bipolar disorder.

METHOD

Participants included 67 adult inpatients and outpatients aged 18-60 years meeting DSM-IV criteria for bipolar disorder (bipolar I and II disorders, bipolar disorder not otherwise specified). We assessed demographic factors, mood symptoms, psychosis, trauma history, trait impulsivity, trait aggression, and reasons for living. The primary outcome measures were the Barratt Impulsiveness Scale-version II, Aggression Questionnaire, and 10 cognitive outcome variables. The cognitive outcome variables assessed cognitive performance across several domains, including processing speed, attention, verbal learning, and executive function. Another aspect of cognitive function, decision making, was assessed using the Iowa Gambling Task. The study was conducted from July 2007-July 2009.

RESULTS

We found that nonattempters reported significantly higher trait impulsivity scores on the Barratt Impulsiveness Scale compared to attempters (t(57) = 2.2, P = .03) and that, among attempters, lower trait impulsivity score was associated with higher scores of lethality of prior attempts (r(25) = -0.53, P = .01). Analyses revealed no other group differences on demographic, clinical, or neurocognitive variables when comparing attempters versus nonattempters. Regression models failed to identify any significant predictors of past suicide attempt.

CONCLUSIONS

The largely negative results of our study are particularly important in highlighting the clinical dilemma faced by many clinicians when trying to predict which patients will make serious suicide attempts and which patients are at a lower risk for acting on suicidal thoughts. A limitation of our work is that we examined stable trait measures of impulsivity among a euthymic sample rather than mood state or the impact of mood state on traits. Overall, we conclude that suicidal behavior is extremely difficult to predict, even when comprehensive clinical and neurocognitive information is available.

Impulsivity in euthymic patients with major depressive disorder: the relation to sociodemographic and clinical properties

The purpose of this study was to examine the trait impulsivity of patients with a major depressive disorder and to explore the possible connections between impulsivity and clinical and sociodemographic variables. The sociodemographic and clinical properties of 60 patients with major depression, who were euthymic according to Hamilton Depression Scale scores, were recorded. Their trait impulsivity was evaluated using the Barratt Impulsiveness Scale (BIS-11) and the impulsivity subscale of the Temperament and Character Inventory, and the results were compared with those of 50 age- and sex-matched healthy controls. We used general linear model analysis to evaluate the manner in which the variables contributed to BIS-11 scores. Some impulsivity scores were higher in those with a major depressive disorder than in comparison subjects. There were significant effects of education and sex in these differences. Elevated BIS-11 scores were associated with a history of psychotic mood episode and suicide attempts. These relationships persisted when age, sex, and education were taken into account. These results show that, after accounting for common confounding factors, trait-like impulsivity was substantially higher in subjects with major depressive disorder than in comparison subjects and may be associated with sociodemographic and clinical properties.

Impulse control disorder comorbidity among patients with bipolar I disorder

OBJECTIVE

Impulsivity is associated with mood instability, behavioral problems, and action without planning in patients with bipolar disorder. Increased impulsivity levels are reported at all types of mood episodes. This association suggests a high comorbidity between impulse control disorders (ICDs) and bipolar disorder. The aim of this study is to compare the prevalence of ICDs and associated clinical and sociodemographic variables in euthymic bipolar I patients.

METHOD

A total of 124 consecutive bipolar I patients who were recruited from regular attendees from the outpatient clinic of our Bipolar Disorder Unit were included in the study. All patients were symptomatically in remission. Diagnosis of bipolar disorder was confirmed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Impulse control disorders were investigated using the modified version of the Minnesota Impulsive Disorders Interview. Impulsivity was measured with the Barratt Impulsiveness Scale Version 11. Furthermore, all patients completed the Zuckerman Sensation-Seeking Scale Form V.

RESULTS

The prevalence rate of all comorbid ICDs in our sample was 27.4% (n = 34). The most common ICD subtype was pathologic skin picking, followed by compulsive buying, intermittent explosive disorder, and trichotillomania. There were no instances of pyromania or compulsive sexual behavior. There was no statistically significant difference between the sociodemographic characteristics of bipolar patients with and without ICDs with regard to age, sex, education level, or marital status. Comorbidity of alcohol/substance abuse and number of suicide attempts were higher in the ICD(+) group than the ICD(-) group. Length of time between mood episodes was higher in the ICD(-) group than the ICD(+) group. There was a statistically significant difference between the total number of mood episodes between the 2 groups, but the number of depressive episodes was higher in the ICD(+) patients as compared with the ICD(-) patients. There was no statistically significant difference between the age of first episode, seasonality, presence of psychotic features, and chronicity of illness. A statistically significant difference was observed between the ICD(+) and ICD(-) groups in terms of total impulsivity, attention, nonplanning, and motor impulsivity scores as determined by the Barratt Impulsiveness Scale Version 11.

CONCLUSION

The present study revealed that there is a high comorbidity rate between bipolar disorder and ICDs based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, criteria. Alcohol/substance use disorders, a high number of previous suicide attempts, and depressive episodes should alert the physician to the presence of comorbid ICDs among bipolar patients that could affect the course and treatment of the disorder.

Impulsivity and aggressiveness in bipolar disorder with co-morbid borderline personality disorder

Few studies to date have been performed to investigate impulsivity and aggressivity in patients with bipolar disorder (BD) and borderline personality disorder (BPD); the primary aim of the present study was to evaluate the impact of co-morbidity of BPD on impulsivity and aggressivity in patients affected by BD. A total of 57 patients (male=20, female=37) affected by BD (BD-I 51%; BD-II 49%) in clinical stable remission were recruited; 28 patients were affected by BD (49.1%), 18 by BD and BPD (31.6%) and 11 (19.3%) by BD plus other personality disorders (OPD) (19.3%). They were assessed with the Structured Clinical Interview for DSM-IV (SCID)-I and SCID-II, and were evaluated by means of the Clinical Global Impression (CGI)-severity and Global Assessment Functioning (GAF) scales, the Barratt Impulsivity Scale (BIS-11) and the Aggression Questionnaire (AQ). Mean total scores were significantly higher among BD/BPD patients with respect to BD and to BD/OPD, both on the BIS-11 and the AQ; the rate of attempted suicides was approximately three times higher in BD/BPD patients with respect to BD and 7.6 times higher than in BD/OPD patients. The results of our study suggest that patients with co-morbid BD and BPD are more impulsive and aggressive. Furthermore, this co-morbid condition may be a risk factor for suicidality.

Quality of life and impulsivity in bipolar disorder

OBJECTIVES

Bipolar disorder (BD) is a chronic psychiatric illness that impairs quality of life (QoL) in numerous life domains even when mood symptoms are not present and is characterized by elevated impulsivity. Many of the comorbid conditions that are associated with diminished QoL in BD also involve impulsivity. The objective of this project was to investigate whether impulsivity might mediate the effects of these comorbid conditions on poor QoL.

METHODS

A total of 76 participants diagnosed with bipolar I disorder by the Structured Clinical Interview for DSM-IV Axis I disorders completed the Quality of Life in Bipolar Disorder (QoL-BD) scale, the Barratt Impulsivity Scale (BIS-11), and the Positive Urgency Measure (PUM). Participants were also assessed for comorbid DSM-IV diagnoses of anxiety, substance use, and impulse control disorders.

RESULTS

Several subscales of the BIS-11 as well as the PUM total score were significantly negatively correlated with overall QoL. PUM total score remained a significant predictor of QoL after controlling for comorbid anxiety, substance use, and impulse control disorders. After controlling for impulsivity, comorbid disorders were no longer significantly related to overall QoL.

CONCLUSIONS

The data support the hypothesis that impulsivity, specifically positive urgency, is highly correlated with QoL in BD. Impulsivity was found to mediate the relation between QoL and several comorbidities in BD. Interventions targeting impulsivity might help to improve QoL in BD.

Mechanisms of impulsivity in bipolar disorder and related illness

Aims – Impulsivity is a multifaceted aspect of behavior that is prominent in psychiatric disorders and has serious behavioral consequences. This paper reviews studies integrating behavioral and physiological mechanisms in impulsivity and their role in severity and course of bipolar and related disorders. Methods – This is a review of work that used questionnaire, human behavioral laboratory, and neurophysiological measurements of impulsivity or related aspects of behavior. Subjects included individuals with bipolar disorder, substance-use disorders, antisocial personality disorder, and healthy controls. Results – Models of impulsivity include rapid-response impulsivity, with inability to reflect or to evaluate a stimulus adequately before responding, and reward-based impulsivity, with inability to delay response for a reward. In normal subjects, rapid-response impulsivity is increased by yohimbine, which increases norepinephrine release. Impulsivity is increased in bipolar disorder, whether measured by questionnaire, by measures of rapid-response impulsivity, or by measures of ability to delay reward. While affective state has differential effects on impulsivity, impulsivity is increased in bipolar disorder regardless of affective state or treatment. Impulsivity, especially rapid-response, is more severe with a highly recurrent course of illness or with comorbid substance-use disorder, and with history of medically severe suicide attempt. In antisocial personality disorder, rapid-response impulsivity is increased, but rewardbased impulsivity is not. In general, impulsivity is increased more in bipolar disorder than in antisocial personality disorder. In combined bipolar disorder and antisocial personality disorder, increased impulsivity is associated with substance-use disorders and suicide attempts. Conclusions – Impulsivity is associated with severe behavioral complications of bipolar disorder, antisocial personality disorder, and substance-use disorders.

Impulsivity in Adolescent Bipolar Disorder

OBJECTIVE

Increased impulsivity has been demonstrated to be a trait feature of adults with bipolar disorder (BD), yet impulsivity has received little study in adolescents with BD. Thus, it is unknown whether it is a trait feature that is present early in the course of the disorder. We tested the hypotheses that self-reported impulsiveness is increased in adolescents with BD, and that it is present during euthymia, supporting impulsiveness as an early trait feature of the disorder.

METHODS

Impulsiveness was assessed in 23 adolescents with BD and 23 healthy comparison (HC) adolescents using the self-report measure of impulsivity, the Barratt Impulsiveness Scale (BIS), comprised by attentional, motor and nonplanning subscale scores. Effects of subscale scores and associations of scores with mood state and course features were explored.

RESULTS

Total and subscale BIS scores were significantly higher in adolescents with BD than HC adolescents. Total, attentional and motor subscale BIS scores were also significantly higher in the subset of adolescents with BD who were euthymic, compared to HC adolescents. Adolescents with BD with rapid-cycling and chronic mood symptoms had significantly higher total and motor subscale BIS scores than adolescents with BD without these course features.

CONCLUSION

These results suggest increased self-reported impulsiveness is a trait feature of adolescents with BD. Elevated impulsivity may be especially prominent in adolescents with rapid-cycling and chronic symptoms.

Criminal conviction, impulsivity, and course of illness in bipolar disorder

OBJECTIVE

Criminal behavior in bipolar disorder may be related to substance use disorders, personality disorders, or other comorbidities potentially related to impulsivity. We investigated relationships among impulsivity, antisocial personality disorder (ASPD) or borderline personality disorder symptoms, substance use disorder, course of illness, and history of criminal behavior in bipolar disorder.

METHODS

A total of 112 subjects with bipolar disorder were recruited from the community. Diagnosis was by Structured Clinical Interview for DSM-IV (SCID-I and SCID-II); psychiatric symptom assessment by the Change version of the Schedule for Affective Disorders and Schizophrenia (SADS-C); severity of Axis II symptoms by ASPD and borderline personality disorder SCID-II symptoms; and impulsivity by questionnaire and response inhibition measures.

RESULTS

A total of 29 subjects self-reported histories of criminal conviction. Compared to other subjects, those with convictions had more ASPD symptoms, less education, more substance use disorder, more suicide attempt history, and a more recurrent course with propensity toward mania. They had increased impulsivity as reflected by impaired response inhibition, but did not differ in questionnaire-measured impulsivity. On logit analysis, impaired response inhibition and ASPD symptoms, but not substance use disorder, were significantly associated with criminal history. Subjects convicted for violent crimes were not more impulsive than those convicted for nonviolent crimes.

CONCLUSIONS

In this community sample, a self-reported history of criminal behavior is related to ASPD symptoms, a recurrent and predominately manic course of illness, and impaired response inhibition in bipolar disorder, independent of current clinical state.

Personality correlates of impulsivity in subjects with generalized anxiety disorders

BACKGROUND

As yet, the relation between personality traits and impulsiveness has not been investigated in subjects affected by generalized anxiety disorder (GAD).

METHOD

A sample of 79 subjects with a diagnosis of GAD has been assessed at intake with Clinical Global Impression (CGI), Barratt Impulsiveness Scale (BIS-11), and with Temperament and Character Inventory. Comorbidity with cluster A or B personality disorders was excluded.

RESULTS

A multiple linear regression has identified 3 variables as independent predictors of impulsiveness: novelty seeking (NS) and reward dependence (RD) as for temperament and self-directedness (SD) as for character. Predictor analysis of the 3 subscales of BIS-11 showed that a higher NS is a predictor of all 3 subscales of BIS-11, whereas a higher RD is a protective factor for the attentive impulsiveness, and a low SD is predictive of a greater nonplanned impulsiveness. The CGI severity index is directly related to motor impulsiveness.

DISCUSSION

Preliminary results showed that in subjects with GAD only the motor component of impulsivity seems directly related to clinical severity, whereas impulsiveness is predicted by higher levels of 2 temperamental dimensions that are influenced by dopamine and norepinephrine systems and by weakness of character.

CONCLUSION

Subjects with GAD showed an interesting variability in NS. Differences in levels of NS and of other temperament (RD) and character (SD) dimensions seem related to different degrees of behavioral inhibition and to a different impact of the cognitive components of impulsiveness. Clinical implications are discussed.

Recent research on impulsivity in individuals with drug use and mental health disorders: implications for alcoholism

Alcohol misuse and dependence, and many of its accompanying psychological problems, are associated with heightened levels of impulsivity that both accelerate the development of clinically significant illness and complicate clinical outcome. This article reviews recent developments in our understanding of impulsivity as they relate to brain circuitry that might underlie these comorbid factors, focusing upon the clinical features of substance use (and dependence), bipolar disorder, and pathological gambling. Individuals who are affected by these disorders exhibit problems in several domains of impulsive behavior including deficient response or "motor" control, and the tolerance of prolonged delays prior to larger rewards at the expense of smaller rewards ("delay-discounting"). These populations, like alcoholic dependents, also exhibit impairments in risky decision-making that may reflect dysfunction of monoamine and catecholamine pathways. However, several areas of uncertainty exist including the specificity of impairments across disorders and the relationship between impulse control problems and altered evaluation of reward outcomes underlying observed impairments in action selection.

Interactions between bipolar disorder and antisocial personality disorder in trait impulsivity and severity of illness

OBJECTIVE

We investigated trait impulsivity in bipolar disorder and antisocial personality disorder (ASPD) with respect to severity and course of illness.

METHOD

Subjects included 78 controls, 34 ASPD, 61 bipolar disorder without Axis II disorder, and 24 bipolar disorder with ASPD, by Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (SCID-I and -II). Data were analyzed using general linear model and probit analysis.

RESULTS

Barratt Impulsiveness Scale (BIS-11) scores were higher in ASPD (effect sizes 0.5-0.8) or bipolar disorder (effect size 1.45) than in controls. Subjects with both had more suicide attempts and previous episodes than bipolar disorder alone, and more substance-use disorders and suicide attempts than ASPD alone. BIS-11 scores were not related to severity of crimes.

CONCLUSION

Impulsivity was higher in bipolar disorder with or without ASPD than in ASPD alone, and higher in ASPD than in controls. Adverse effects of bipolar disorder in ASPD, but not of ASPD in bipolar disorder, were accounted for by increased impulsivity.

Do euthymic bipolar patients have normal cognitive functioning?

PURPOSE OF REVIEW

Research on the neurocognitive functions of bipolar patients has yielded inconsistent results over recent years. There is a growing need for clarification regarding the magnitude, clinical relevance and confounding variables of cognitive impairment in bipolar patients.

RECENT FINDINGS

Current findings of studies investigating executive functions, psychomotor speed and memory functions suggest heterogeneous cognitive functioning in patients. A significant amount of variance can be attributed to treatment factors or interactions of those factors with the course of illness and individual characteristics. Furthermore, cognitive domains are presumably inter-related. The impact of bipolar illness on cognition can be influenced by age of onset, pharmaceutical treatment approaches, individual response, familial risk factors, and clinical features. Although brain activation patterns appear to be altered, these alternations do not necessarily correlate with impairment in cognitive performance. Without carefully controlling for confounding variables, the actual effect of bipolar disorder on cognitive performance scores cannot be evaluated.

SUMMARY

Cognitive deficits of clinical relevance are documented for a substantial proportion, but not the majority, of bipolar patients. Yet, available data are inconclusive with respect to the origin of these deficits. Future studies on cognitive deficits in bipolar patients need to deliver detailed descriptions of drug treatment and clinical features.

Impulsivity across the course of bipolar disorder

OBJECTIVE

To determine whether abnormalities of impulse control persist across the course of bipolar disorder, thereby representing potential state markers and endophenotypes.

METHODS

Impulse control of 108 bipolar I manic or mixed patients was measured on three tasks designed to study response inhibition, ability to delay gratification, and attention; namely, a stop signal task, a delayed reward task, and a continuous performance task, respectively. Barrett Impulsivity Scale (BIS-11) scores were also obtained. Patients were then followed for up to one year and reassessed with the same measures if they developed depression or euthymia. Healthy comparison subjects were also assessed with the same instruments on two occasions to assess measurement stability.

RESULTS

At baseline, bipolar subjects demonstrated significant deficits on all three tasks as compared to healthy subjects, consistent with more impulsive responding in the bipolar manic/mixed group. In general, performance on the three behavioral tasks normalized upon switching to depression or developing euthymia. In contrast, BIS-11 scores were elevated during mania and remained elevated as bipolar subjects developed depression or achieved euthymia.

CONCLUSIONS

Bipolar I disorder patients demonstrate deficits on laboratory tests of various aspects of impulsivity when manic, as compared to healthy subjects, that largely normalize with recovery and switching into depression. However, elevated BIS-11 scores persist across phases of illness. These findings suggest that impulsivity has both affective-state dependent and trait components in bipolar disorder.

Temperament at 5 years of age predicts amygdala and orbitofrontal volume in the right hemisphere in adolescence

It was of interest to determine if hemispheric differences in orbitofrontal cortex (OFC) volume would be related to behavioral inhibition observed in a peer-play setting. Magnetic resonance imaging (MRI) was carried out in 23 individuals (19 males and 4 females) at an average age of 14.87+/-1.14 years who were either at high or low risk for alcohol dependence. All subjects had previously been evaluated in a preschool peer play paradigm (5.03+/-0.78 years) assessing behavioral inhibition. Region of interest measures were traced for the OFC and the amygdala, and confirmed with voxel based morphometry. Behavioral inhibition, a behavioral tendency that often occurs in a novel setting in reaction to strangers, includes the following: greater time spent next to the mother, greater time staring at another child, and longer latency to begin play with another child. A significant relationship was seen between greater right OFC volume and indicators of behavioral inhibition including greater time spent proximal to their mother and greater time staring at the other child. Also, larger amygdala volume was associated with more time spent proximal to the mother. Behavioral control, including both over- and under-control, is likely to be subserved by neural circuitry associated with emotion regulation including the right OFC and the amygdala.

Validity and Reliability of the Abbreviated Barratt Impulsiveness Scale in Spanish (BIS-15S)

OBJECTIVE: This study determined the validity and reliability of a new, abbreviated version of the Spanish Barratt Impulsiveness Scale (BIS-15S) in Colombian subjects. METHOD: The BIS-15S was tested in non-clinical (n=283) and clinical (n=164) native Spanish-speakers. Intra-scale reliability was calculated using Cronbach's α, and test-retest reliability was measured with Pearson correlations. Psychometric properties were determined using standard statistics. A factor analysis was performed to determine BIS-15S factor structure. RESULTS: 447 subjects participated in the study. Clinical subjects were older and more educated compared to non-clinical subjects. Impulsivity scores were normally distributed in each group. BIS-15S total, motor, non-planning and attention scores were significantly lower in non-clinical vs. clinical subjects. Subjects with substance-related disorders had the highest BIS-15S total scores, followed by subjects with bipolar disorders and bulimia nervosa/binge eating. Internal consistency was 0.793 and test-retest reliability was 0.80. Factor analysis confirmed a three-factor structure (attention, motor, non-planning) accounting for 47.87% of the total variance in BIS-15S total scores. CONCLUSIONS: The BIS-15S is a valid and reliable self-report measure of impulsivity in this population. Further research is needed to determine additional components of impulsivity not investigated by this measure.

Impulsivity in mania

Impulsivity, a breakdown in the balance between initiation and screening of action that leads to reactions to stimuli without adequate reflection or regard for consequences, is a core feature of bipolar disorder and is prominent in manic episodes. Catecholaminergic function is related to impulsivity and mania. Manic individuals have abnormal dopaminergic reactions to reward and abnormal responses in the ventral prefrontal cortex that are consistent with impulsive behavior. Impulsivity in mania is pervasive, encompassing deficits in attention and behavioral inhibition. Impulsivity is increased with severe course of illness (eg, frequent episodes, substance use disorders, and suicide attempts). In mixed states, mania-associated impulsivity combines with depressive symptoms to increase the risk of suicide. Clinical management of impulsivity in mania involves addressing interpersonal distortions inherent in mania; reducing overstimulation; alertness to medical-, trauma-, or substance-related problems; and prompt pharmacologic treatment. Manic episodes must be viewed in the context of the life course of bipolar disorder.

Anterior genu corpus callosum and impulsivity in suicidal patients with bipolar disorder

Suicidality is a life-threatening symptom in patients with bipolar disorder (BD). Impulsivity and mood instability are associated with suicidality in mood disorders. Evidence suggests that gray and white matter abnormalities are linked with impulsivity in mood disorders, but little is known about the association between corpus callosum (CC) and impulsivity in BD. We examined the relationship between CC areas, impulsivity and suicidality in BD patients. We studied 10 female BD patients with a history of suicide attempt (mean+/-SD age 36.2+/-10.1 years), 10 female BD patients without suicide attempt history (44.2+/-12.5 years) and 27 female healthy subjects (36.9+/-13.8 years). Impulsivity was evaluated by the Barratt Impulsivity Scale (BIS). We traced MR images to measure the areas of the CC genu, anterior body, posterior body, isthmus and splenium. The genu was divided into anterior, middle and posterior regions. The suicidal and non-suicidal BD patients had significantly higher BIS total, attention and non-planning scores than the healthy subjects (ps<0.01), and the suicidal BD patients had significantly higher BIS motor scores than the non-suicidal BD and healthy subjects (ps<0.01). There were no significant differences among the three groups on any regional CC areas, although the suicidal BD patients had the smallest areas. The suicidal BD patients showed a significant inverse correlation between anterior genu area and the BIS total (r=-0.75, p=0.04), motor (r=-0.79, p=0.02) and non-planning scores (r=-0.79, p=0.02). These correlations were not found in the non-suicidal BD patients or healthy subjects. The results suggest that the anterior medial frontal region may be involved in the pathophysiology of impulsive and suicidal behaviors in BD.

Trait impulsivity and response inhibition in antisocial personality disorder

BACKGROUND

Impulsive behavior is a prominent characteristic of antisocial personality disorder. Impulsivity is a complex construct, however, representing distinct domains of cognition and action. Leading models refer to impulsivity as an inability to evaluate a stimulus fully before responding to it (rapid-response impulsivity), and as an inability to delay responding despite a larger reward (reward-delay impulsivity). We investigated these models in terms of the diagnosis and severity of antisocial personality disorder.

METHODS

Thirty-four male subjects on probation/parole who met DSM-IV criteria for ASPD, and 30 male healthy comparison subjects, matched by ethnicity, were recruited from the community. The Barratt Impulsiveness Scale (BIS-11) provided an integrated measure of trait impulsivity. Rapid-response impulsivity was assessed using the Immediate Memory Task (IMT), a continuous performance test. Reward delay impulsivity was assessed using the Two-choice Impulsivity Paradigm (TCIP), where subjects had the choice of smaller-sooner or larger-delayed rewards, and the Single Key Impulsivity Paradigm (SKIP), a free-operant responding task.

RESULTS

Compared to controls, subjects with ASPD had higher BIS-11 scores (Effect Size (E.S.)=0.95). They had slower reaction times to IMT commission errors (E.S.=0.45). Correct detections, a measure of attention, were identical to controls. On the SKIP, they had a shorter maximum delay for reward (E.S.=0.76), but this was not significant after correction for age and education. The groups did not differ on impulsive choices on the TCIP (E.S.<0.1). On probit analysis with age and education as additional independent variables, BIS-11 score, IMT reaction time to a commission error, and IMT positive response bias contributed significantly to diagnosis of ASPD; SKIP delay for reward did not. Severity of ASPD, assessed by the number of ASPD symptoms endorsed on the SCID-II, correlated significantly with commission errors (impulsive responses) on the IMT, and with liberal IMT response bias. This relationship persisted with correction for age and education.

DISCUSSION

These results suggest that ASPD is characterized by increased rapid-response impulsivity. Aspects of impulsivity related to reward-delay or attention appear relatively intact.