The externalizing and internalizing pathways to marijuana use initiation: Examining the synergistic effects of impulsiveness and sensation seeking.

Adolescent marijuana use has become increasingly more problematic compared with the past; thus, understanding developmental processes that increase the liability of marijuana use is essential. Two developmental pathways to adolescent substance use have been proposed: an externalizing pathway that emphasizes the expression of aggressive and delinquent behavior, and an internalizing pathway that emphasizes the role of depressive symptoms and negative affect. In this study, we aimed to examine the synergistic role of impulsiveness and sensation seeking in the two risk pathways to determine whether both high and low levels of the traits are risk factors for marijuana use. Our study included 343 adolescents (52% were girls, 78% identified as Hispanic) that oversampled high-risk youth (78% had a family history of substance use disorder), assessed biannually between the ages of 13-16 years old. Moderated mediation analyses revealed that high levels of sensation seeking indirectly predicted marijuana use through higher mean levels of externalizing behavior. The positive relationship between sensation seeking and externalizing behavior was only significant at high levels of impulsiveness. Conversely, low levels of sensation seeking indirectly predicted marijuana use through higher mean levels of internalizing behavior. The negative relationship between sensation seeking and internalizing behavior was only significant at low levels of impulsiveness. Collectively, these results demonstrate that high and low levels of both impulsiveness and sensation seeking confer increased risk of marijuana use, albeit through different mechanisms. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The Development of Externalizing and Internalizing Behaviors Among Youth With or Without a Family History of Substance Use Disorder: The Indirect Effects of Early-Life Stress and Impulsivity.

Youth with a family history of substance use disorder (FH+) are more prone to have externalizing and internalizing problems compared to youth without a family history of substance use disorder (FH-), increasing the likelihood of later maladjustment. However, mechanisms for this association remain understudied. In this longitudinal study, we examined if FH+ youth are more likely to experience early-life stressors (ELS), which in turn would increase impulsivity and the expression of externalizing and internalizing behaviors. Data were collected from youth and a parent (n = 386) during a baseline assessment (age 10-12 years) and every six months when the youth was 13-16 years old. In support of the primary hypothesis, FH+ youth reported higher levels of externalizing and internalizing behaviors through ELS to impulsivity providing a developmental pathway through which FH+ youth are more prone to externalizing and internalizing problems.

Psychiatric aspects of impulsivity.

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

Antisocial personality disorder, alcohol, and aggression.

Epidemiologic studies and laboratory research consistently link alcohol use with aggression. Not all people, however, exhibit increased aggression under the influence of alcohol. Recent research suggests that people with antisocial personality disorder (ASPD) may be more prone to alcohol-related aggression than people without ASPD. As a group, people with ASPD have higher rates of alcohol dependence and more alcohol-related problems than people without ASPD. Likewise, in laboratory studies, people with ASPD show greater increases in aggressive behavior after consuming alcohol than people without ASPD. The association between ASPD and alcohol-related aggression may result from biological factors, such as ASPD-related impairments in the functions of certain brain chemicals (e.g., serotonin) or in the activities of higher reasoning, or "executive," brain regions. Alternatively, the association between ASPD and alcohol-related aggression may stem from some as yet undetermined factor(s) that increase the risk for aggression in general.

Endogenous plasma testosterone levels and commission errors in women: A preliminary report.

A correlation between elevated testosterone and aggressive behavior has been demonstrated in animals and to a lesser degree in humans, primarily in the context of dominance. Some aggression, namely non-premeditated aggression, is characterized by impaired impulse control. Real-world aggressive histories and self-reported impulsivity have correlated with commission errors (failures to withhold responses to nontarget stimuli) in versions of the continuous performance test (CPT). To begin exploring whether testosterone may play a role in aggression due more to a direct relationship with impaired impulse control, we related plasma total testosterone concentrations of 27 psychiatrically healthy women to commission errors in two variants of the CPT - with and without interstimulus distracters. Controlling for age and IQ, testosterone did not relate to rates of correct detections in either task, but correlated positively with commission errors in the distracter CPT variant. In light of the fact previous studies find commission errors on the CPT are associated with impulsivity, the results of this study support a positive relationship between testosterone and impulsivity.

Measurement of inter-episode impulsivity in bipolar disorder.

We carried out a preliminary investigation of impulsivity in patients with bipolar I disorder not meeting criteria for active episodes. Barratt Impulsiveness Scale (BIS-11) scores were significantly higher in bipolar disorder than in control subjects. Laboratory measurements of impulsivity correlated with a BIS-11 score or severity of manic symptoms. Impulsivity in bipolar disorder may have both stable and state-dependent aspects.

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

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

Effects of moderate and high doses of alcohol on attention, impulsivity, discriminability, and response bias in immediate and delayed memory task performance.

BACKGROUND: Prior studies that examined the effects of alcohol on Continuous Performance Test (CPT) performance have resulted in inconsistent outcomes. Most studies that examined the effects of alcohol on concentrated attention tasks (like the CPT) found little effect of alcohol on performance measures, even when doses that exceeded 0.8 g/kg were used. One likely reason for these inconsistencies is the varying difficulty (and sensitivity) of the task used, and as a result, comparisons between studies are difficult. This study is one in a series that examines the effects of alcohol on attention by using a difficult version of the CPT (Immediate and Delayed Memory Task--IMT/DMT). Our purpose for these studies has been two-fold, examining the effects of alcohol (1) on concentrated attention (i.e., correct detections) and (2) on errors (i.e., commission errors) previously correlated with impulsive behaviors. The first is important because previous studies have shown little effect of alcohol on attention, and the second is important because commission errors have been related to impulsive behaviors. METHODS: In the IMT/DMT, participants respond to a briefly displayed number when it is identical to the one displayed before it. The procedure includes immediate and delayed conditions where successive stimuli to be matched are delayed by 0.5 sec or by 3.5 sec. The three stimulus types included target (identical match), catch (four of five digits match), and filler (no match) stimuli. Twenty subjects completed this task after consuming either a placebo drink or a drink that contained 0.5 g/kg or 1.0 g/kg of alcohol on different days. RESULTS: The main findings were that (1) alcohol decreased the percentage of correct identifications of target stimuli; (2) alcohol increased the percentage of commission errors in relation to the number of correct target responses; and (3) alcohol decreased discriminability whereas response bias became more conservative. CONCLUSIONS: These results clearly demonstrated a time-course effect of the 1.0 g/kg alcohol dose on attention, impulsivity, discrimination, and response criteria when a variety of dependent measures are used.

Low dose zolmitriptan as a 5-HT neuroendocrine challenge agent in humans.

The 5-HT1B/D agonist sumatriptan has been used in a number of studies as a neuroendocrine challenge agent. Whether its neuroendocrine effects are centrally mediated is unclear, however, since sumatriptan shows minimal penetration of the central nervous system. Zolmitriptan shows a greater penetration into the central nervous system than sumatriptan, and has recently been shown to be an effective challenge agent. In order to determine the neuroendocrine, temperature and side effects of a 2.5 mg oral dose of zolmitriptan, 17 healthy volunteers underwent a placebo controlled, repeated measures, double blind neuroendocrine challenge. Zolmitriptan or placebo were administered, and cortisol, growth hormone, prolactin, blood pressure and temperature, were measured over four hours after the dose of zolmitriptan. Zolmitriptan at this dose was well tolerated by all subjects, with minimal side effects and only minor effects on blood pressure. There was a significant increase in serum growth hormone after zolmitriptan compared to placebo, however there were no significant effects on cortisol, prolactin or oral temperature. The neuroendocrine effects of 2.5 mg of orally administered zolmitriptan are similar to previously reported effects of sumatriptan, with minimal side effects.

Differential behavioral effects of plasma tryptophan depletion and loading in aggressive and nonaggressive men.

Preliminary findings indicate that men with high trait hostility may be prone to aggression increases following plasma tryptophan (Trp) depletion. We measured laboratory aggression in men selected for presence (n = 12) or absence (n = 12) of aggressive histories. Testing occurred before and after plasma Trp depletion, Trp loading, and under a food-restricted control condition. Subjects were provoked by subtractions of money, and aggression was measured as the responses the subject made to ostensibly subtract money from the instigator of the subtractions. When subjects were highly provoked, there was a significant Trp condition x aggression history interaction effect on aggressive responding. In particular, laboratory aggression in aggressive men was elevated under Trp-depleted conditions relative to Trp-loaded conditions, whereas the opposite occurred in nonaggressive men. Moreover, plasma total Trp levels after Trp loading were significantly higher in nonaggressive men, and plasma free (but not total) Trp levels after Trp loading correlated negatively with aggressive responses in the aggressive men. These data corroborate earlier findings that aggressive men may be more prone to aggression induced by reductions in plasma Trp.

Alcohol increases commission error rates for a continuous performance test.

BACKGROUND: Studying the effects of alcohol on Continuous Performance Test (CPT) performance was of interest for two reasons, i.e., (1) perhaps because of the ease of the task used in previous experiments, alcohol has not been found to impair performance, and (2) CPT commission errors (described below) have been related to impulsive behavior. METHODS: In this study, the CPT featured both an Immediate Memory Task (IMT) and a more difficult Delayed Memory Task (DMT). We compared the performance of 18 subjects under both alcohol and placebo conditions, using a within-subject design. Both the IMT (0.5-sec delay) and the DMT (3.5-sec delay, with distracter stimuli at 0.5-sec intervals) required the subject to respond if a briefly displayed number was identical to the one presented before it. Stimuli included target (identical match), catch (4 of 5 digits matched), and novel (random number) stimuli. On 2 separate days, subjects performed between administrations of three hourly placebo drinks or three hourly drinks containing 0.20 g/kg of alcohol (producing peak breath alcohol concentrations of approximately 0.035%). RESULTS: The main finding was that alcohol consumption increased responses to catch stimuli (i.e., commission errors) in the DMT. In contrast, performance in the IMT (the easier task) was unaffected by alcohol. Commission errors measured during peak breath alcohol concentrations were significantly correlated with scores on the Barratt Impulsivity Scale for both the IMT and DMT. Discriminability (A') between target and catch stimuli was reduced by alcohol for the DMT only. CONCLUSIONS: These data indicate that even small amounts of alcohol can produce measurable changes in CPT performance parameters if the task is of sufficient difficulty and that commission errors can be increased by alcohol consumption.

The effects of a cumulative alcohol dosing procedure on laboratory aggression in women and men.

OBJECTIVE: This study directly compared the effects of cumulative alcohol dosing procedure on aggression in both women and men. METHOD: Thirteen women and 13 men consumed three beverages 1 hour apart. There were two experimental conditions: (1) a placebo day, when subjects consumed three 240 ml beverages, each containing only 1 ml of alcohol; and (2) an alcohol day, when subjects consumed three 240 ml beverages, each containing 0.35 g/kg of 95% alcohol. Alcohol doses for women were reduced by 8%. Prior to beverage consumption, and periodically after consumption, subjects participated in 25-minute laboratory testing sessions designed to measure aggression. In this paradigm, subjects could earn points by responding on a button, or aggress toward a fictitious opponent who ostensibly subtracted earnings from them. RESULTS: Both women and men showed an increase in aggressive responding after drinking alcohol but not placebo. As a group the greatest increases were observed after consuming the second alcohol drink (BAC = 0.08%). Aggressive responding, however, remained elevated for several hours after alcohol consumption. A post hoc analysis of the data indicated that subjects with high aggression levels under placebo conditions showed the greatest increases in aggression under alcohol conditions. CONCLUSIONS: These results indicate that at least under these conditions, alcohol does increase aggression in both women and men. The aggression-increasing effects of alcohol appear to be long-lasting and specific to individuals with the higher aggressive tendencies while sober.

Laboratory measures of aggression and impulsivity in women with borderline personality disorder.

To characterize how severe negative affect in women is reflected in objective measures of aggression and impulsivity, the aggressive and impulsive behavior of 14 hospitalized women with borderline personality disorder (BPD) was compared with that of 17 controls. In an impulsivity task, subjects experienced two sets of 50 trials during which they could choose a smaller, immediate monetary reward or a larger but progressively delayed reward. In a separate task (PSAP), subjects earned monetary reinforcers with repeated button presses, and were provoked by the subtraction of money which was blamed on a fictitious other participant. Subjects could respond by ostensibly subtracting money from the fictitious subject (the aggressive response). While selection frequency of the short-delay responses was similar in patients and controls, BPD patients responded to avoid longer delay of reward across trials, and had higher Barratt Impulsiveness Scale total scores and attentional subscale scores. BPD patients responded to the money losses with roughly three times as many aggressive responses as controls and had higher Buss-Durkee Hostility Inventory (BDHI), Brown History of Violence, and Retrospective Overt Aggression Scale scores than controls. Aggressive responding rates correlated positively with BDHI scores. These results extend previous findings that negative affect in women is reflected in laboratory behavioral measures.

The effects of tryptophan depletion and loading on laboratory aggression in men: time course and a food-restricted control.

Some studies have shown that sharp reduction of L-tryptophan (Trp) concentration in plasma results in increases in laboratory-measured aggression. Conversely, raising plasma Trp has blunted aggression. These effects are presumably due to impaired or enhanced serotonin synthesis and neurotransmission in the brain. In this study, the laboratory-measured aggressive behavior of eight men under both Trp depletion (T-) and Trp loading (T+) conditions was compared to their aggressive behavior under food-restricted control conditions (overnight fast without an amino acid beverage). Subjects were provoked by periodic subtraction of money which was attributed to a fictitious other participant, and aggression was defined as the number of retaliatory responses the subject made ostensibly to reduce the earnings of the (fictitious) other participant. Following ingestion of the T- beverage, aggressive responding was significantly elevated relative to the food-restricted control condition, and this increased aggressive behavior became more pronounced across behavioral testing sessions on a time-course which paralleled previously documented decreases in plasma Trp concentrations. In contrast, no changes were observed in aggressive responding under T+ conditions relative to food-restricted conditions. These within-subject behavioral changes under depleted plasma Trp conditions support earlier indications of a role of serotonin in regulating aggression.

Symptomatology of depression and anxiety in female "social drinkers".

Self-reported alcohol use, Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI) scores were obtained during on-site interviews of 172 female applicants for paid participation in behavioral research. Mood symptomatology as reflected in BDI and BAI scores was analyzed as a function of alcohol use and other demographic variables. Women reporting even light alcohol use (up to three drinks per week) were significantly more symptomatic than abstinent women. In contrast, no significant differences in symptomatology were observed due to race or education level. This analysis extends previous findings of depressed mood in women (while sober) whose lifestyle includes moderate alcohol consumption and suggests that even light alcohol use is related to depressed and/or anxious mood.

Influence of trait hostility on tryptophan depletion-induced laboratory aggression.

Previous research has indicated that laboratory aggression in men increases after temporarily reducing the synthesis and neurotransmission of serotonin (5-HT) in the brain using the plasma L-tryptophan (Trp) depletion technique. Further research indicates that male subjects selected for high trait hostility are particularly prone to increased aggression following plasma Trp depletion. In a recent study of laboratory aggression in male control subjects, we demonstrated that laboratory aggression increased following ingestion of a Trp-depleting beverage, but not after ingestion of a Trp-containing beverage nor under food-restricted conditions. We report here that the increases in aggression under Trp-depleted conditions were specific to men who scored the highest on the Buss-Perry Aggression Questionnaire. These preliminary data support earlier findings that compared to non-hostile men, hostile men may be more prone to behavior change induced by the perturbation of the 5-HT neurotransmitter system.

Plasma L-tryptophan depletion and aggression.

There is a well-established relationship between aggression and lowered serotonin neuro-transmission. Recently developed methodologies for manipulating L-tryptophan levels (and brain serotonin) have been applied to human laboratory studies of aggression. Collectively, these studies provide further evidence for the serotonin-aggression relationship. Two important findings have been made recently: (1) subsets of individuals (e.g., persons self-rating high on aggressive or hostility scales) may differ in their susceptibility to aggression produced through plasma tryptophan depletion; and (2) alcohol in combination with L-tryptophan depletion has an additive effect on aggression. All previous studies have been conducted with men. Extending these studies to women appears to be the much-needed next step given that serotonergic levels appear to vary both as a function of the menstrual cycle phase and menstrual symptomatology.

Ipsapirone neuroendocrine challenge: relationship to aggression as measured in the human laboratory.

Thirty-one human subjects were administered a neuroendocrine challenge with the 5-HT1a agonist ipsapirone after completing six sessions of a laboratory measure of aggression, the Point Subtraction Aggression Paradigm (PSAP), in order to determine if a laboratory measure of aggression was related to serotonin function. Subjects who showed more aggressive responding on the PSAP (n = 11) had a significantly blunted temperature response to ipsapirone compared to those with less aggressive responding (n = 20). There was no difference between the two groups on the cortisol response to ipsapirone. This study supports a relationship between serotonin function and aggression as measured in the human laboratory, similar to the well-documented association between self-reported aggression and serotonin.

Self-reported impulsivity is correlated with laboratory-measured escape behavior.

Aggression has been previously correlated with impulsive personality. In the present study, Barratt Impulsiveness Scale (BIS) scores of 40 male controls aged 15-40 years were related to the frequency of free-operant aggressive and escape responses toward a fictitious antagonist. Participants earned "points" worth money with repeated button presses on a fixed-ratio schedule and were provoked by the periodic subtraction of a point. These subtractions were blamed on the behavior of a (fictitious) other participant, and aggressive responses (presses of a separate button) were defined as those emitted by the participant with an intent to subtract earnings from the other (fictitious) participant. BIS scores were not correlated with frequency of point-subtracting (aggressive) responses to the point subtractions, but they were correlated with the frequency of escape responses on a third button, which the participant was told would protect his points from subtraction for an unspecified period of time. These results suggest that among normal controls, impulsivity might be characterized by some sensitivity to aversive stimuli.