Orwik

Effects of acute tryptophan depletion on three types of behavioral impulsivity

Drinking histories in alcohol-use-disordered youth: preliminary findings on relationships to platelet serotonin transporter expression with genotypes of the serotonin transporter.

OBJECTIVE: The serotonin (5-HT) transporter (5-HTT) is thought to play a key role in the onset of alcohol use, with potential behavioral and biological mechanisms mediated by the level of 5-HT in the synapse and in cerebral spinal fluid. Although 5-H... expand abstractT dysregulation has been related to poor impulse control, the biological mechanism is unknown, although functional control of the serotonergic system has been shown to be regulated in part by differential expression of the 5-HTT. The gene responsible for encoding 5-HTT has a functional polymorphism at the 5'-regulatory promoter region, which results in two forms: long (L) and short (S). The LL genotype is hypothesized to play a key role in the early onset of alcohol use and may be related to poor impulse control. The objective of this pilot study is to determine whether adolescents with a current alcohol-use disorder (AUD) (N = 21) have platelet measures of the 5-HTT functioning that are related to 5-HTT genotype and poor impulse control. Specifically, we wanted to examine the relationships between the following: platelet 5-HTT and 5-HTT genotype; platelet 5-HTT parameters and age at onset, as well as duration of drinking; and 5-HTT genotype and impulse control. METHOD: Adolescents with current AUD were recruited from the community to participate in a cross-section pilot study. RESULTS: Our main findings showed significantly higher paroxetine binding (density of 5-HTT) in LL genotype versus S carriers (SS or SL genotypes); also, the LL group had a significantly earlier age at onset of drinking and longer duration of drinking, and poorer impulse control. CONCLUSIONS: These findings provide partial support for the hypothesis that, among currently drinking adolescents with an AUD, differential expression of 5-HTT may play an important role in the onset of adolescent AUD. collapse abstract

Impulsivity and clinical symptoms among adolescents with non-suicidal self-injury with or without attempted suicide.

This study examined clinical characteristics and laboratory-measured impulsive behavior of adolescents engaging in either non-suicidal self-injury with (NSSI+SA; n=25) or without (NSSI-Only; n=31) suicide attempts. We hypothesized that adolescent wit... expand abstracth NSSI+SI would exhibit more severe clinical symptoms and higher levels of behavioral impulsivity compared to adolescents with NSSI-Only. Adolescents were recruited from an inpatient psychiatric hospital unit and the two groups were compared on demographic characteristics, psychopathology, self-reported clinical ratings, methods of non-suicidal self-injury, and two laboratory impulsivity measures. Primary evaluations were conducted during psychiatric hospitalization, and a subset of those tested during hospitalization was retested 4-6 weeks after discharge. During hospitalization, NSSI+SA patients reported worse depression, hopelessness, and impulsivity on standard clinical measures, and demonstrated elevated impulsivity on a reward-directed laboratory measure compared to NSSI-Only patients. In the follow-up analyses, depression, hopelessness, suicidal ideation, and laboratory impulsivity were improved for both groups, but the NSSI+SA group still exhibited significantly more depressive symptoms, hopelessness, and impulsivity than the NSSI-Only group. Risk assessments for adolescents with NSSI+SA should include consideration not only of the severity of clinical symptoms but of the current level impulsivity as well. collapse abstract

Distinctions in behavioral impulsivity: Implications for substance abuse research

L-tryptophan: Basic metabolic functions, behavioral research, and therapeutic indications

Adaptive Visual Analog Scales (AVAS): a modifiable software program for the creation, administration, and scoring of visual analog scales.

The Adaptive Visual Analog Scales is a freely available computer software package designed to be a flexible tool for the creation, administration, and automated scoring of both continuous and discrete visual analog scale formats. The continuous forma... expand abstractt is a series of individual items that are rated along a solid line and scored as a percentage of distance from one of the two anchors of the rating line. The discrete format is a series of individual items that use a specific number of ordinal choices for rating each item. This software offers separate options for the creation and use of standardized instructions, practice sessions, and rating administration, all of which can be customized by the investigator. A unique participant/patient ID is used to store scores for each item, and individual data from each administration are automatically appended to that scale's data storage file. This software provides flexible, time-saving access for data management and/or importing data into statistical packages. This tool can be adapted so as to gather ratings for a wide range of clinical and research uses and is freely available at www.nrlc-group.net. collapse abstract

Differentiating impulsive and premeditated aggression: self and informant perspectives among adolescents with personality pathology.

Previous research has articulated the conceptual differentiation of impulsive and premeditated aggression. Little, if any, of this research has examined personological differences among adolescents with aggression-oriented pathology, and little, if a... expand abstractny, has examined both self and informant perspectives. The current study examined such differentiation within a Conduct Disorder population in which normal and pathological personality characteristics were examined via self- and informant-report. Results indicated the two forms of aggression were independent: high impulsive aggression was associated with high Neuroticism, but high premeditated aggression was associated with low Agreeableness and high Extraversion. Overall, adolescents high in impulsive aggression had a pattern of personality characteristics that are seen as socially-detached and emotionally volatile. In contrast, adolescents high in premeditated aggression had a pattern of characteristics seen as egocentric and socially-engaged but without concern for others. The results have implications for the social and motivational mechanisms producing the two forms of aggression. collapse abstract

Impulsive and premeditated subtypes of aggression in conduct disorder: differences in time estimation.

Research aimed at identifying and studying subtypes of aggression have historically dichotomized aggressive subtypes, although specific nomenclature has varied; one approach has been to classify aggressive behavior as predominantly impulsive or predo... expand abstractminantly premeditated. There are a number of behavioral and cognitive differences between those exhibiting these different forms of aggression. This study was designed to extend understanding of the impulsive/premeditated aggression dichotomy by comparing time estimation among adolescents exhibiting predominantly impulsive or predominantly premeditated forms of physical aggression who have a psychiatric diagnosis of conduct disorder (CD). Time estimation has previously been shown to be disrupted in impulsive and some aggressive individuals. Time estimation was compared between healthy Controls (n = 37) and two groups of adolescents with CD, those with histories of either predominantly impulsive (CD-Impulsive, n = 26) or predominantly premeditated (CD-Premeditated, n = 38) aggressive behaviors. Participants completed five computerized trials during which they estimated when 1 min had passed. Among aggressive adolescents with CD, the misperception of time was specific to those with histories of impulsive aggression, although time estimates improved with repeated testing and performance feedback. This study confirms the importance of considering the role and type of physical aggression when studying heterogeneous diagnostic groups like CD and supports the relevance of time estimation to certain subgroups of adolescents with CD. collapse abstract

Adolescent suicidal behavior and substance use: Developmental mechanisms

Prospective study of cannabis withdrawal in cannabis-using adolescents.

GENDER COMPARISON OF BREATHALCOHOL CONCENTRATIONS FOLLOWING BOLUS AND HOURLY ALCOHOL DOSING PROCEDURES USING MULTIPLE ALCOHOL DOSES

Many studies using alcohol administration assess breath alcohol concentrations (BrACs) in both men and women. To account for physiological differences and equate BrACs between men and women, alcohol doses are often reduced by 8% for women. Despite th... expand abstracte use of this dose adjustment, a comprehensive comparison of the time course of men's and women's BrAC measurements following multiple alcohol doses has not been conducted. Using both bolus and hourly dosing procedures, we examined whether an 8% dose reduction for women results in BrACs similar to men regardless of dose size, measurement time, or method of administration. Two groups of moderate drinkers from 21 through 45 years old were recruited for this study. In a repeated-measures design, one group of 90 men and women (n = 45 each) each consumed bolus doses of 0.2, 0.4, 0.6, and 0.8 g/kg 95% alcohol at 9:00 AM on separate days. Expired-air samples were collected at 9:30, 10:15, and 11:15 AM. In the second group, 26 men and women (n = 13 each) consumed 0.35 g/kg 95% alcohol in three hourly doses at 9:15, 10:15, and 11:15 AM. Expired-air samples were collected at 9:30, 10:30, and 11:30 AM and 12:30 and 1:30 PM. Results: Both bolus and hourly dosing procedures resulted in comparable BrAC measurements for men and women following all alcohol doses across all measurement time points. Following bolus dosing, peak BrACs reached .007%, .032%, .059%, and .087% for women, and .010%, .034%, .060%, and .086% for men (doses 0.2, .04, .06, 0.8 g/kg, respectively). Following hourly dosing (0.35 g/kg x 3), peak BrACs were .108% for women and .112% for men. This comprehensive comparison of a wide range of alcohol doses and measurement times using two administration procedures strongly supports the use of an 8% reduction of alcohol dose for women to equate BrAC with men. collapse abstract

Comparison of 50- and 100-g L -tryptophan depletion and loading formulations for altering 5-HT synthesis: pharmacokinetics, side effects, and mood states.

RATIONALE: Differences in 5-hydroxytryptamine (5-HT) function have been the subject of extensive research in psychiatric studies. Many studies have manipulated L -tryptophan (Trp) levels to temporarily decrease (depletion) or increase (loading) 5-HT ... expand abstractsynthesis. While most researchers have used a 100-g formulation, there has been ongoing interest in using smaller-sized formulations. OBJECTIVES: This study examined the time course of multiple plasma indicators of brain 5-HT synthesis after a 50-g depletion and loading as a comparison to the corresponding 100-g formulations that are typically used. MATERIALS AND METHODS: Plasma was collected from 112 healthy adults at seven hourly intervals after consumption of either a 50- or 100-g depletion or loading. Self-ratings of mood and somatic symptoms were completed before and after Trp manipulations. RESULTS: The primary findings were that (1) the 50- and 100-g formulations produced the expected changes in plasma indicators after both depletion (-89% and -96%, respectively) and loading (+570% and +372%, respectively); (2) the 100-g depletion showed more robust effects at the 4, 5, and 6 h measurements than the 50-g depletion; (3) there was significant attrition after both the 100-g depletion and loading, but not after either of the 50-g formulations; and (4) both the 50- and 100-g depletions produced increases in negative self-ratings of mood and somatic symptoms, while loading significantly increased negative ratings after the 100 g only. CONCLUSIONS: There are important considerations when choosing among formulation sizes for use in Trp manipulation studies, and the complete 7-h time-course data set of the typical plasma Trp measures presented here may help researchers decide which methodology best suits their needs. collapse abstract

A test of alcohol dose effects on multiple behavioral measures of impulsivity.

BACKGROUND: Acute alcohol administration affects impulsive behavior, although these effects vary as a function of alcohol dose, assessment instrument, and time of measurement following administration. METHODS: We concurrently examined the dose-depend... expand abstractent effects of alcohol on three distinct types of impulsivity tasks (continuous performance [IMT], stop-signal [GoStop], and delay-discounting [SKIP] tasks). Ninety healthy alcohol drinkers were assigned to one of the three task groups (n=30 each), each group experienced placebo, 0.2, 0.4, 0.6, and 0.8 g/kg alcohol doses across 5 experimental days, and task performance was assessed at 0.5h before and 0.25, 1.0, and 2.0 h after alcohol administration. We hypothesized that impulsive responding on all tasks would be increased by acute alcohol administration both across time and during the peak BrAC, but the magnitude would depend on the task being tested. Analyses included the time course and the peak BrAC effects. Task comparisons of peak behavioral changes following each dose are illustrated using standardized scores. RESULTS: While alcohol consumption increased impulsive responding during all three tasks to some extent, our hypothesis was only partially supported. During the IMT, the 0.6 and 0.8 g/kg doses produced increased impulsive responding across time and at the peak BrAC. However, during the GoStop and SKIP, impulsivity increased across time regardless of the alcohol dose size, with no differences in impulsive responding among dose conditions at peak BrAC. CONCLUSIONS: This study demonstrated alcohol-induced changes in impulsivity are not uniformly affected by alcohol. These data, in conjunction with previous studies, further support that impulsivity is not a unitary construct. collapse abstract

Behavioral measures of impulsivity and the law

Personality judgment and personality pathology: self-other agreement in adolescents with conduct disorder.

We examine two issues linking personality pathology and judgment of traits within the Five-Factor Model of personality. We hypothesize that pathology moderates self-other agreement--"target" participants with pathology should be less judgable than pa... expand abstractrticipants without pathology. In addition, we hypothesize that pathology could partially produce agreement across a variety of traits, particularly those traits fundamental to the pathology. In an adolescent sample including a group with Conduct Disorder (CD) and a Control group, we examine agreement between adolescents' self-reports and their mothers' informant reports. Using trait-centered and person-centered perspectives, we find support for both hypotheses. Results have implications for understanding the processes affecting personality judgment, for increasing integration of traditional personality research and personality pathology, and for personality assessment. collapse abstract

Teenagers do not always lie: characteristics and correspondence of telephone and in-person reports of adolescent drug use.

Because of the widespread use of drugs by adolescents, there is demand for scientific rigor in sampling and accuracy in methods for ascertaining drug use patterns. The present study: (1) characterized adolescents who responded to advertisements for m... expand abstractarijuana users; (2) compared rates of drug use reported on the telephone versus an on-site interview; and (3) examined drug use patterns as a function of parental awareness of drug use. Adolescents, identifying themselves as marijuana users during telephone interviews, reported more use of other drugs than those denying marijuana use. There was a high degree of correspondence between telephone and on-site interviews for all drugs except alcohol, which was reported at a higher rate on-site. Of those reporting marijuana use in the past week, 69% tested positive for marijuana in their urine-drug screens. Finally, marijuana and alcohol use patterns were higher among adolescents whose parents were aware of drug use than those whose parents indicated that their adolescent did not use marijuana. These results indicate that adolescents are willing to self-identify as marijuana users and report drug and alcohol use during telephone interviews. Additionally, parents appear to become more aware of their adolescent's drug use with increased frequency of use. collapse abstract

Characterizing aggressive behavior with the ImpulsivePremeditated Aggression Scale among adolescents with conduct disorder.

This study extends the use of the Impulsive/Premeditated Aggression Scale for subtyping aggressive behavior among adolescents with Conduct Disorder. Of the Conduct Disorder symptoms, aggression has the strongest prognostic and treatment implications.... expand abstract While aggression is a complex construct, convergent evidence supports a dichotomy of impulsive and premeditated aggressive subtypes that are qualitatively different from one another in terms of phenomenology and neurobiology. Previous attempts at measuring subtypes of aggression in children and adults are not clearly generalizable to adolescents. Sixty-six adolescents completed a questionnaire for characterizing aggression (Impulsive/Premeditated Aggression Scale), along with standard measures of personality and general functioning. Principal components analysis demonstrated two stable factors of aggression with good internal consistency and construct validity. Compared to the premeditated aggression factor, the impulsive aggression factor was associated with a broader range of personality, thought, emotional, and social problems. As in the adult and child literature, characterization of aggressive behavior into two subtypes appears to be relevant to understanding individual differences among adolescents with Conduct Disorder. collapse abstract

The effects of alcohol on laboratory-measured impulsivity after L: -Tryptophan depletion or loading.

RATIONALE: Indirect evidence supports a link between serotonergic activity and individual differences in the behavioral response to alcohol, but few studies have experimentally demonstrated that an individual's biological state can influence the sens... expand abstractitivity to alcohol-induced behaviors. OBJECTIVE: Our purpose was to temporarily modify serotonin synthesis in healthy individuals to determine how altered biological states may interact with alcohol administration to affect impulsive behavior. MATERIALS AND METHODS: In a repeated-measures design, 18 normal controls consumed a 50-g L: -tryptophan (Trp) depleting (ATD) or loading (ATL) amino-acid beverage that temporarily decreased or increased (respectively) serotonin synthesis before receiving either a moderate dose of alcohol (0.65 g/kg) or placebo. All participants completed three impulsivity testing sessions on each of the five experimental days. Session one was a baseline session. Session two included testing after ATD-only or ATL-only. Session three included: (1) placebo after ATL (ATL+PBO); (2) placebo after ATD (ATD+PBO); (3) alcohol after ATL (ATL+ALC); (4) alcohol after ATD (ATD+ALC); and (5) Alcohol-only conditions. Impulsivity was assessed using the Immediate Memory Task (Dougherty et al., Behav Res Methods Instrum Comput 34:391-398, 2002), a continuous performance test yielding commission errors that have been previously validated as a component of impulsive behavior. RESULTS: Primary findings were that ATD-only increased impulsive responding compared to ATL-only, and ATD+ALC increased commission errors to levels higher than either the ATL+ALC or Alcohol-only conditions. CONCLUSIONS: These findings demonstrate that reduced serotonin synthesis can produce increased impulsivity even among non-impulsive normal controls, and that the behavioral effects of alcohol are, in part, dependent on this biological state. collapse abstract

Behavioral impulsivity in adolescents with Conduct Disorder who use Marijuana

Laboratory measured behavioral impulsivity relates to suicide attempt history.

The purpose of this study was to examine the relationship between laboratory behavioral measured impulsivity (using the Immediate and Delayed Memory Tasks) and suicidal attempt histories. Three groups of adults were recruited, those with either: no p... expand abstractrevious suicide attempts (Control, n = 20), only a single suicide attempt (Single, n = 20), or multiple suicidal attempts (Multiple, n = 10). As hypothesized, impulsive responses increased with the number of suicide attempts (Control < Single < Multiple). This study helps to demonstrate how laboratory behavioral measures of impulsivity can be used to discriminate groups based on suicidal histories among samples not currently exhibiting significant suicidal behaviors. collapse abstract

Laboratory behavioral measures of impulsivity.

Previous research and theory have conceptualized impulsivity as a multifaceted construct that requires multiple modes of measurement for accurate assessment. This article describes a software package that includes four paradigms for measuring multipl... expand abstracte and unique aspects of impulsivity. Specifically, four tasks are described: (1) the two choice impulsivity paradigm, (2) the single key impulsivity paradigm, (3) the GoStop impulsivity paradigm, and (4) the time paradigm. These tasks measure processes related to the capacity to tolerate delay for reward, to inhibit an already initiated response, and to estimate the passage of time. These processes have been found to be important to the understanding of impulsive behaviors. The programs are flexible and allow the experimenter to manipulate a number of parameters related to delay-reward contingencies, timing, performance feedback/payment, and data output variables. Manipulation of these parameters makes the paradigms scalable to a wide range of ability levels and appropriate for samples ranging from children to adults. The four paradigms in this software package are available at no cost and can be obtained by contacting the corresponding author. collapse abstract

Suicidal behaviors and drug abuse: impulsivity and its assessment.

Impulsivity appears to play an important role in suicidal behaviors and drug abuse, which are two psychiatric problems that may interact with one another. Interpretation of the literature on impulsivity in these behaviors may be complicated by the va... expand abstractriety of measurement techniques for the assessment of impulsivity. There are three general types of impulsivity assessment: self-report, biological, and laboratory behavioral. Because laboratory behavioral measures both meet an operational definition of impulsivity and are sensitive to state-dependent changes in impulsivity, this paper presents data that focuses on laboratory behavioral performance among samples emitting suicidal behaviors or substance abuse. To better account for influence of impulsivity in these psychiatric disturbances, no single source of measurement should be used without the consideration of other types of instruments. collapse abstract

P300 event-related potential amplitude and impulsivity in cocaine-dependent subjects.

Previous studies report reduced amplitude of the P300 event-related potential in cocaine-dependent individuals. Cocaine dependence is also associated with increased impulsivity, possibly due to deficits in cognitive function that are associated with ... expand abstractreduced P300 amplitude. In the current study, the relationship between cocaine dependence, impulsivity, and P300 amplitude were examined. An auditory oddball event-related potential task along with self-report (Barratt Impulsiveness Scale version 11) and behavioral laboratory (Immediate and Delayed Memory Task) measures of impulsivity were assessed in healthy controls (n = 14) and subjects who met DSM-IV criteria for current cocaine dependence (n = 17). P300 amplitude was reduced and self-reported and behavioral laboratory impulsivity scores were elevated among the cocaine-dependent group compared to controls. There was a positive correlation between the questionnaire and behavioral laboratory measures of impulsivity, and a negative correlation between impulsivity measures and P300 amplitude. The correlation between self-reported impulsivity scores and P300 amplitude remained after taking into account the number of childhood conduct disorder symptoms. This study supports the hypothesis that the basic neurophysiology responsible for the P300 amplitude in cocaine-dependent individuals is associated with impulsivity independent of a history of childhood conduct disorder symptoms. collapse abstract

The physiological experience of the Paced Auditory Serial Addition Task (PASAT): does the PASAT induce autonomic arousal?

Previous research suggests that the Paced Auditory Serial Attention Task (PASAT) alters mood states, which may induce performance changes and complicate interpretation test scores. In the current design, we examined arousal as one mechanism moderatin... expand abstractg PASAT performance. It was expected that arousal level would increase during the test, and performance on the test would be related to arousal level. Heart rate and blood pressure (systolic and diastolic) were recorded from 42 healthy adult men during rest and PASAT challenge. Heart rate and blood pressure were significantly higher and stable across the PASAT procedure, while performance scores showed a steady decrease in correct responses. No association of arousal level and performance was found. Although, PASAT induced arousal changes were not significantly related to performance among healthy adults, the observed arousal changes do raise concerns about interpretation of PASAT performance among more sensitive populations and indicate new areas of application of the procedure. collapse abstract

Age at first drink relates to behavioral measures of impulsivity: the immediate and delayed memory tasks.

BACKGROUND: This study examined the relationship between laboratory-measured impulsivity and age at first drink. METHODS: Using a laboratory behavioral measure of impulsivity [Immediate (IMT) and Delayed Memory Tasks (DMT)], we compared two groups of... expand abstract women differing in their self-reported age at first drink (early-onset drinking, age <18 years, n = 40; late-onset drinking, age > or =21 years, n = 23). It was expected that those who first consumed alcohol before the legal drinking age (i.e., early onset) would perform in a more impulsive manner on the laboratory behavioral measure than the late-onset drinkers. RESULTS: The main finding was that the early-onset group (IMT: mean, 28.7%; DMT: mean, 30.4%) had increased commission error rates compared with the late-onset group (IMT: mean, 21.2%; DMT: mean, 15.5%) during both the IMT [ANOVA:F (1,61) = 4.30; p = 0.042; f = 0.27] and DMT [F (1,61) = 10.76; p = 0.002; f = 0.42]. Age at first drink was significantly correlated with DMT commission errors (r = -0.23; p = 0.037), although this was only at the trend level for IMT commission errors (r = -0.20; p = 0.062); these correlations are likely to be underestimates because of range restriction of the age variable. CONCLUSIONS: These results demonstrate that differences in impulsive behavioral responding are distinguishable even between groups of alcohol drinkers who are not experiencing clinically significant problems with alcohol. collapse abstract