Impact of group motivational interviewing on enhancing treatment engagement for homeless Veterans with nicotine dependence and other substance use disorders: A pilot investigation.

BACKGROUND: Prior studies have shown that Group Motivational Interviewing (GMI) for dually diagnosed patients holds promise for increasing treatment engagement. OBJECTIVES: The current study evaluated the impact of a novel GMI protocol that included tobacco-specific components (referred to as "Tobacco GMI or T-GMI") targeting enhanced engagement in smoking cessation treatment. METHODS: Thirty-seven primary alcohol and nicotine-dependent cigarette smoking homeless Veterans with co-morbid psychiatric conditions were recruited to receive four GMI sessions over 4 consecutive days. The first 16 participants received standard GMI, aimed at enhancing engagement in substance abuse treatment and for reducing substance use, while the remaining 21 participants received a modified "tobacco-specific" GMI protocol (T-GMI) that included additional content specific to cessation of tobacco use and enhancing smoking cessation treatment, in addition to the standard substance abuse content of GMI. RESULTS: Participants in T-GMI were more likely to attend tobacco cessation programming (p = .05), as well as to attend combined tobacco cessation programming with prescribed nicotine replacement therapy (p = .03), compared to those in standard GMI. Differences between treatment conditions with respect to alcohol and illicit drug use outcomes were not significant, although overall substance use declined over time in both groups. CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE: Results suggest that inclusion of tobacco-specific components in the context of GMI for substance abuse may enhance treatment engagement for tobacco cessation behaviors among dually diagnosed nicotine dependent homeless patients, a highly vulnerable population for which interventional resources targeting engagement in smoking cessation treatment has historically been lacking. (Am J Addict 2016;25:533-541).

Menstrual cycle phase effects in the gender dimorphic stress cue reactivity of smokers.

INTRODUCTION: We previously reported that female smokers evidence greater subjective craving and stress/emotional reactivity to personalized stress cues than males. The present study employed the same dataset to assess whether females in the follicular versus luteal phase of the menstrual cycle accounted for the gender differences. METHODS: Two objective criteria, onset of menses and luteinizing hormone surge (evaluated via home testing kits), were used to determine whether female smokers were in either the follicular (n = 22) or the luteal (n = 15) phase of their menstrual cycle, respectively. The females and a sample of male smokers (n = 53) were then administered a laboratory-based cue reactivity paradigm that involved assessment of craving, stress, and emotional reactivity in response to counterbalanced presentations of both a personalized stress script and neutral/relaxed script. RESULTS: While there were no significant differences between females in the follicular versus luteal phase on any outcome measure, females in the luteal menstrual phase reported greater craving than males whereas females in the follicular phase reported greater stress and arousal than males and perceived the stress cues as more emotionally aversive than males. CONCLUSIONS: This preliminary investigation suggests that gender differences in craving versus affective responding to stress cues may, in part, be explained variation by menstrual cycle phase. Study limitations and implications of the findings for future research and treatment are briefly discussed.

Craving, cue reactivity, and stimulus control among early-stage young smokers: effects of smoking intensity and gender.

INTRODUCTION: Smoking initiation usually begins in adolescence, but how and for whom nicotine dependence emerges during this period is unclear. The cue-reactivity paradigm is well suited to examine one marker of dependence: craving-related stimulus control, i.e., the ability of environmental cues to elicit craving to smoke. This study examined the effects of both level of smoking involvement (daily vs. occasional smoking) and gender on reactivity to both smoking and alcohol cues. METHODS: Young (age range 16-20; 42% female) daily (n = 55) and occasional (n = 52) smokers were exposed to each of three counterbalanced cues: (a) in vivo smoking (e.g., sight, smell, lighting of cigarette), (b) alcohol (e.g., opening, pouring, and smell of preferred beverage), and (c) neutral cue. RESULTS: Daily smokers exhibited higher levels of tonic (i.e., noncue-elicited) craving than did occasional smokers. Both groups showed significant increases in craving in response to cues (i.e., cue-elicited craving), with little evidence that cue-elicited craving differed between groups. Females were more cue reactive to both the alcohol and smoking cues than males, particularly for the positively reinforced aspects of smoking (i.e., hedonic craving). There were no gender × group interaction effects in response to either the alcohol or the smoking cue. CONCLUSIONS: Findings show the presence of cue-elicited craving even among occasional smokers and are consistent with literature demonstrating heightened sensitivity to environmental cues among females. Cue-elicited craving may be one mechanism that contributes to the maintenance of smoking behavior and perhaps to the development of nicotine dependence within early stage smokers.

Brief motivational feedback may enhance treatment entry in veterans with comorbid substance use and psychiatric disorders.

BACKGROUND AND OBJECTIVES: There are limited investigations of brief interventions to facilitate treatment entry among individuals with substance use disorders. This study investigated the effectiveness of brief motivational feedback (BMF) for increasing entry into intensive substance abuse treatment in veteran patients. METHODS: Veteran patients (N = 84) with substance use disorders referred for an intake assessment in a substance abuse specialty clinic received either (i) intake assessment plus BMF or (ii) intake assessment as usual (AAU). BMF consisted of brief motivational enhancement feedback pertaining to estimates of alcohol and drug consumption, money spent on drugs and alcohol, and self-reported problems due to substance abuse. Primary outcome was entry in treatment groups in an intensive outpatient program for substance abuse. RESULTS: Patients in BMF and AAU conditions did not significantly differ on indices of treatment entry. However, among patients with comorbid substance dependence and psychiatric disorders, those who received BMF were significantly more likely to enter outpatient treatment groups. CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE: The addition of motivational feedback to a standard intake assessment enhanced substance abuse treatment entry among veteran patients with comorbid substance use disorders and psychiatric disorders. These preliminary findings extend the use of motivational feedback to facilitate entry into substance abuse treatment among veteran patients with comorbid substance use and psychiatric disorders. Furthermore, they suggest opportunity for more effective patient-treatment matching based on initial motivation and other individual factors such as psychiatric comorbidity.

A double-blind placebo-controlled trial of N-acetylcysteine in the treatment of cocaine dependence.

BACKGROUND: There remains no FDA approved medication for the treatment of cocaine dependence. Preclinical studies and early pilot clinical investigations have suggested that N-acetylcysteine (NAC) may be useful in the treatment of the disorder. OBJECTIVE: The present report assessed the efficacy of NAC in the treatment of cocaine dependence. METHODS: Cocaine-dependent volunteers (n = 111) were randomized to receive daily doses of 1,200 mg of NAC, 2,400 mg of NAC, or placebo. Participants were followed for 8 weeks (up to three visits weekly). At each of these visits, urine samples were collected, along with self-reports of cocaine use. Urine samples were assessed for quantitative levels of benzoylecognine (ie, cocaine metabolite). RESULTS: Overall, the primary results for the clinical trial were negative. However, when considering only subjects who entered the trial having already achieved abstinence, results favored the 2,400 mg NAC group relative to placebo, with the 2,400 mg group having longer times to relapse and lower craving ratings. CONCLUSION: While the present trial failed to demonstrate that NAC reduces cocaine use in cocaine-dependent individuals actively using, there was some evidence it prevented return to cocaine use in individuals who had already achieved abstinence from cocaine. SCIENTIFIC SIGNIFICANCE: N-acetylcysteine may be useful as a relapse prevention agent in abstinent cocaine-dependent individuals.

Gender differences in craving and cue reactivity to smoking and negative affect/stress cues.

There is evidence that women may be less successful when attempting to quit smoking than men. One potential contributory cause of this gender difference is differential craving and stress reactivity to smoking- and negative affect/stress-related cues. The present human laboratory study investigated the effects of gender on reactivity to smoking and negative affect/stress cues by exposing nicotine dependent women (n = 37) and men (n = 53) smokers to two active cue types, each with an associated control cue: (1) in vivo smoking cues and in vivo neutral control cues, and (2) imagery-based negative affect/stress script and a neutral/relaxing control script. Both before and after each cue/script, participants provided subjective reports of smoking-related craving and affective reactions. Heart rate (HR) and skin conductance (SC) responses were also measured. Results indicated that participants reported greater craving and SC in response to smoking versus neutral cues and greater subjective stress in response to the negative affect/stress versus neutral/relaxing script. With respect to gender differences, women evidenced greater craving, stress and arousal ratings and lower valence ratings (greater negative emotion) in response to the negative affect/stressful script. While there were no gender differences in responses to smoking cues, women trended towards higher arousal ratings. Implications of the findings for treatment and tobacco-related morbidity and mortality are discussed.

Does alexithymia explain variation in cue-elicited craving reported by methamphetamine-dependent individuals?

Drug craving is an important motivational phenomenon among addicted individuals, and successful management of craving is essential to both the initiation and maintenance of abstinence. Although craving in response to drug cues is common in drug-dependent individuals, it is not universal. At the present time, it is not known why approximately 20-30% of all addicted persons fail to report appreciable craving in laboratory-based cue reactivity studies. This study examined the possibility that alexithymia, a personality attribute characterized by a difficulty identifying and describing emotions, may contribute to the impoverished cue-elicited craving experienced by some addicts. Specifically, we tested the hypothesis that alexithymia, as measured by the Toronto Alexithymia Scale (TAS), would be inversely related to the magnitude of cue-elicited craving obtained in a cue reactivity protocol. Forty methamphetamine-dependent individuals completed the TAS and provided craving ratings for methamphetamine after presentation of methamphetamine-associated cues. Thirteen participants (32%) reported no methamphetamine cue-elicited craving. Contrary to expectation, TAS factor 1 (a measure of difficulty identifying feelings) scores were positively associated with cue-elicited craving. Thus, the results suggest that increasing difficulty-identifying feelings may be associated with higher cue-elicited craving. Clinical implications for this finding are discussed.

Impaired cognitive performance in subjects with methamphetamine dependence during exposure to neutral versus methamphetamine-related cues.

BACKGROUND: Chronic methamphetamine abuse is associated with cognitive deficits that may impede treatment in methamphetamine-dependent patients. Exposure to methamphetamine-related cues can elicit intense craving in chronic users of the drug, but the effects of exposure to drug cues on cognitive performance in these individuals are unknown. OBJECTIVES: This study assessed whether exposure to methamphetamine-related visual cues can elicit craving and/or alter dual task cognitive performance in 30 methamphetamine-dependent subjects and 30 control subjects in the laboratory. METHODS: Reaction time, response errors, and inhibition errors were assessed on an auditory Go-No Go task performed by adult participants (total N = 60) while watching neutral versus methamphetamine-related video cues. Craving was assessed with the Within-Session Rating Scale modified for methamphetamine-dependent subjects. RESULTS: Exposure to methamphetamine-related cues elicited craving only in methamphetamine-dependent subjects. Even in the absence of methamphetamine cues, methamphetamine-dependent subjects exhibited slower reaction times and higher rates of both inhibition and response errors than control subjects did. Upon exposure to methamphetamine cues, rates of both response errors and inhibition errors increased significantly in methamphetamine-dependent subjects. Control subjects exhibited no increase in inhibition errors and only slightly increased rates of response errors upon exposure to methamphetamine cues. Response error rates, but not inhibition error rates or reaction times, during methamphetamine cue exposure were significantly associated with craving scores in methamphetamine-dependent subjects. CONCLUSIONS AND SIGNIFICANCE: Methamphetamine-dependent individuals exhibit cognitive performance deficits that are more pronounced during exposure to methamphetamine-related cues. Interventions that reduce cue reactivity may have utility in the treatment of methamphetamine dependence.

Randomized controlled trial of group motivational interviewing for veterans with substance use disorders.

BACKGROUND: Motivational interviewing delivered in a group format is understudied yet promising as a treatment for substance use disorders (SUD). We evaluated the efficacy of group motivational interviewing (GMI) relative to a treatment-control (TCC) for enhancing treatment and self-help engagement and decreasing alcohol and drug use among veterans with SUD and co-existing psychiatric disorders. METHOD: Veterans (n = 118) with alcohol use disorder were recruited within an outpatient SUD treatment program and randomized to GMI or TCC upon program entry. Alcohol use, SUD treatment, and 12-step session attendance were primary outcomes. Drug use days was the secondary outcome. Participants were assessed at baseline and at one-and three-month follow-up. RESULTS: Significant differences were observed between GMI and TCC for binge drinking at both one (RR = .74; 95 % CI [.58, .94]) and three-month follow-up (RR = .74; 95 % CI [.59, .91]). At three-month follow-up, significant differences between treatment conditions were observed for alcohol use days (RR = .79; 95 % CI [.67, .94]), number of SUD treatment sessions (RR = 2.53; 95 % CI [1.99, 3.22]), and 12-step sessions attended (RR = 1.64; 95 % CI [1.35-1.98]). Similarly, we observed significant effects for GMI on reducing alcohol consumption in standard drinks (RR = .49; 95 % CI [.25, .95]). Drug use days declined at each follow-up, with no significant differences between treatment conditions. CONCLUSIONS: GMI delivered at SUD treatment program entry enhanced treatment session and 12-step group attendance and lowered alcohol consumption among outpatient Veterans. Future research should study how GMI works and its effectiveness in SUD treatment settings.

Menstrual cycle and cue reactivity in women smokers.

INTRODUCTION: Emerging research suggests potential effects of the menstrual cycle on various aspects of smoking behavior in women, but results to date have been mixed. The present study sought to explore the influence of menstrual cycle phase on reactivity to smoking in vivo and stressful imagery cues in a sample of non-treatment-seeking women smokers. METHODS: Via a within-subjects design, nicotine-dependent women (N = 37) participated in a series of four cue reactivity sessions, each during a distinct biologically verified phase of the menstrual cycle (early follicular [EF], mid-follicular [MF], mid-luteal [ML], and late luteal [LL]). Subjective (Questionnaire of Smoking Urges-Brief; QSU-B) and physiological (skin conductance and heart rate) measures of craving and reactivity were collected and compared across phases. RESULTS: Subjective reactive craving (QSU-B) to smoking in vivo cues varied significantly across the menstrual cycle (p = .02) and was higher in both EF and MF phases versus ML and LL phases, but this finding was not sustained when controlling for reactivity to neutral cues. Heart rate reactivity to stressful imagery cues (p = .01) and skin conductance reactivity to smoking in vivo cues (p = .05) varied significantly across the menstrual cycle upon controlling for reactivity to neutral cues, with highest reactivity during the MF phase. DISCUSSION: Menstrual cycle phase may have an effect on reactivity to smoking-related and stressful cues among women smokers. These findings contribute to an expanding literature, suggesting menstrual cycle effects on smoking behaviors in women.

Menstrual phase effects on smoking cessation: a pilot feasibility study.

BACKGROUND AND OBJECTIVES: A growing body of research suggests that nicotine withdrawal and cigarette craving may vary across the menstrual cycle and that the luteal phase of the cycle may be associated with increases in each. This potential relationship suggests that careful timing of quit attempts during the menstrual cycle may improve initial success at abstinence, although there are no direct tests of this approach yet published. Our objectives were to preliminarily test the effect of timing of quit attempts for smoking cessation relative to menstrual cycle and to identify methodological procedures that could guide subsequent, larger clinical trials. METHODS: In this pilot study, we randomized female smokers aged 18-40 who were not currently using hormonal contraception to quit smoking during either the follicular (n = 25) or luteal phase (n = 19) of their menstrual cycle. Participants were provided with two sessions of smoking cessation counseling (90 minutes total). All participants were provided with a transdermal nicotine patch contingent on maintenance of abstinence throughout the course of the 6-week study. RESULTS: Among participants who initiated treatment, received the patch, and made a quit attempt (n = 35), carbon monoxide-verified repeated point prevalence abstinence 2 weeks after the target quit date was higher in the follicular than the luteal group (32% vs. 19%, respectively; OR = 2.0, 95% CI = 0.4-9.8). Within the overall study population, this difference was slightly lower (24% vs. 16%; OR = 1.7, 95% CI = 0.4-7.8). CONCLUSIONS: Timing quit attempts based on menstrual phase is feasible. Insights gained from this study and the recommendations made herein may inform future research on this important clinical question.

Cue reactivity in young marijuana smokers: a preliminary investigation.

To develop and evaluate the feasibility of a cue reactivity paradigm for young marijuana smokers, the authors set up a laboratory procedure involving neutral and marijuana-related imagery, video, and in vivo cues. Fifteen adolescents and young adults with cannabis use disorders completed the procedure, which included continuous measurement of skin conductance and heart rate. Participants also completed questionnaires regarding marijuana craving before, during, and after cue presentations. Higher levels of craving and skin conductance were observed during marijuana cue presentations. The procedure appears to elicit cue reactivity among adolescents and young adults with cannabis use disorders and should be further evaluated and refined with a larger sample. Implications for future studies are discussed.

Paradoxical olfactory function in combat veterans: The role of PTSD and odor factors.

Stress- and trauma-related disorders, including posttraumatic stress disorder (PTSD), are characterized by an increased sensitivity to threat cues. Given that threat detection is a critical function of olfaction and that combat trauma is commonly associated with burning odors, we sought a better understanding of general olfactory function as well as response to specific trauma-related (i.e. burning) odors in combat-related PTSD. Trauma-exposed combat veterans with (N = 22) and without (N = 25) PTSD were assessed for general and specific odor sensitivities using a variety of tools. Both groups had similar general odor detection thresholds. However, the combat veterans with PTSD, compared to combat veterans with comparable trauma exposure, but without PTSD, had increased ratings of odor intensity, negative valence, and odor-triggered PTSD symptoms, along with a blunted heart rate in response to burning rubber odor. These findings are discussed within the context of healthy versus pathological changes in olfactory processing that occur over time after psychological trauma.

Is cocaine desire reduced by N-acetylcysteine?

OBJECTIVE: Animal models suggest that N-acetylcysteine inhibits cocaine-seeking. The present pilot study evaluated whether N-acetylcysteine would suppress reactivity to cocaine-related cues in cocaine-dependent humans. METHOD: In this double-blind, placebo-controlled trial, 15 participants received N-acetylcysteine or placebo during a 3-day hospitalization. Participants were crossed over to receive the opposite condition on a second, identical 3-day stay occurring 4 days later. During each hospital stay, participants completed a cue-reactivity procedure that involved collecting psychophysical and subjective data in response to slides depicting cocaine and cocaine use. RESULTS: While taking N-acetylcysteine, participants reported less desire to use and less interest in response to cocaine slides and watched cocaine slides for less time. CONCLUSIONS: The inhibition of cocaine cue reactivity is consistent with existing preclinical data and supports the use of N-acetylcysteine as a treatment for cocaine dependence.

An open-label trial of N-acetylcysteine for the treatment of cocaine dependence: a pilot study.

Recent preclinical studies implicate N-acetylcysteine (NAC), a cysteine prodrug, as a potential medication for preventing relapse to cocaine use; however, little is known about the safety and tolerability of NAC in cocaine-dependent subjects in an outpatient setting. This pilot study examines the safety and tolerability of 3 doses of NAC for the treatment of cocaine dependence. Twenty three treatment-seeking cocaine-dependent patients participated in a 4-week medication trial and received NAC at doses of 1200 mg/day, 2400 mg/day or 3600 mg/day. Results suggested that the three doses were well tolerated. Overall, the retention rates appeared to favor higher doses of NAC (2400 mg/day and 3600 mg/day). The majority of subjects who completed the study (n=16) either terminated use of cocaine completely or significantly reduced their use of cocaine during treatment. Overall the findings suggest that it is feasible to treat cocaine-dependent treatment seekers with N-acetylcysteine on an outpatient basis.

Reactivity to nicotine cues over repeated cue reactivity sessions.

The present study investigated whether reactivity to nicotine-related cues would attenuate across four experimental sessions held 1 week apart. Participants were nineteen non-treatment seeking, nicotine-dependent males. Cue reactivity sessions were performed in an outpatient research center using in vivo cues consisting of standardized smoking-related paraphernalia (e.g., cigarettes) and neutral comparison paraphernalia (e.g., pencils). Craving ratings were collected before and after both cue presentations while physiological measures (heart rate, skin conductance) were collected before and during the cue presentations. Although craving levels decreased across sessions, smoking-related cues consistently evoked significantly greater increases in craving relative to neutral cues over all four experimental sessions. Skin conductance was higher in response to smoking cues, though this effect was not as robust as that observed for craving. Results suggest that, under the described experimental parameters, craving can be reliably elicited over repeated cue reactivity sessions.

Effect of a Brief Memory Updating Intervention on Smoking Behavior: A Randomized Clinical Trial.

IMPORTANCE: Recent research on addiction-related memory processes suggests that protracted extinction training following brief cue-elicited memory retrieval (ie, retrieval-extinction [R-E] training) can attenuate/eradicate the ability of cues to elicit learned behaviors. One study reported that cue-elicited craving among detoxified heroin addicts was substantially attenuated following R-E training and through 6-month follow-up. OBJECTIVE: To build on these impressive findings by examining whether R-E training could attenuate smoking-related craving and behavior. DESIGN, SETTING, AND PARTICIPANTS: This prospective, mixed-design, human laboratory randomized clinical trial took place between December 2013 and September 2015. Participants were recruited in Charleston, South Carolina. Study sessions took place at the Medical University of South Carolina. The participants were 168 screened volunteer smokers, of whom 88 were randomized; 72 of these 88 participants (81.8%) attended all the follow-up sessions through 1 month. The primary eligibility criteria were current nicotine dependence (DSM criteria), smoking 10 or more cigarettes per day, and a willingness to attempt smoking cessation. INTERVENTIONS: Participants were randomly assigned to receive either smoking-related memory retrieval followed by extinction training (the R-E group) or nonsmoking-related retrieval followed by extinction training (the NR-E group). MAIN OUTCOMES AND MEASURES: Primary outcomes were cue-elicited craving and physiological responding to familiar and novel cues in the R-E group vs the NR-E group over a 1-month follow-up period. Secondary outcomes were smoking-related behaviors. RESULTS: A total of 44 participants were randomly assigned to the R-E group (mean age, 48.3 years; 72.7% male); a total of 44 participants were randomly assigned to the NR-E group, with 43 attending at least 1 training session (mean age, 46.7 years; 55.8% male). The mean craving response to both familiar and novel smoking cues was significantly lower for participants in the R-E group than for participants in the NR-E group at 1-month follow-up (for both cue types: t1225 = 2.1, P = .04, d = 0.44, and Δ = 0.47 [95% CI, 0.04-0.90]). The mean numbers of cigarettes smoked per day at 2 weeks and 1-month were significantly lower for the R-E group than for the NR-E group (treatment main effect: F1,68 = 5.4, P = .02, d = 0.50, and Δ = 2.4 [95% CI, 0.4-4.5]). Significant differences in physiological responses, urine cotinine level, number of days abstinent, lapse, and relapse were not observed between groups (all between P = .06 and .75). CONCLUSIONS AND RELEVANCE: Retrieval-extinction training substantially attenuated craving to both familiar and novel smoking cues and reduced the number of cigarettes smoked per day by participants 1 month after treatment relative to extinction training alone. Between-group differences were not observed for physiological responses, cotinine level, number of days abstinent, relapse, or lapse. In summary, R-E training is a brief behavioral treatment that targets smoking-related memories and has the potential to enhance relapse prevention. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT02154685.

PTSD and the HPA axis: differences in response to the cold pressor task among individuals with child vs. adult trauma.

Hypothalamic pituitary adrenal (HPA) axis and subjective stress response to a cold-water immersion task, the cold pressor task (CPT), in individuals (N=89) with post-traumatic stress disorder (PTSD) were examined. All tests were conducted at 08:00h after an overnight hospital stay. Plasma adrenocorticotrophin hormone (ACTH), cortisol, and subjective stress were examined at baseline and five post-task time points in controls (n=31), subjects with PTSD as a result of an index trauma during childhood (i.e. before age 18; n=25), and subjects with PTSD as a result of an index trauma as an adult (n=33). Approximately, 50% of individuals in both trauma groups were alcohol dependent, and the impact of this comorbidity was also examined. Subjects with PTSD, regardless of age of index trauma, had a less robust ACTH response as compared to controls. Regardless of the presence or absence of comorbid alcohol dependence, subjects with childhood trauma had lower cortisol at baseline and at all post-task measurement points and did not demonstrate the decrease in cortisol over the course of the 2h monitoring period seen in subjects with adult index trauma and controls. The findings reveal differences in the neuroendocrine response to the CPT in individuals with PTSD compared to control subjects, and differences in PTSD subjects when examined by age of index trauma.

Personality correlates of startle habituation.

This study investigated the relationship between extraversion and rates of acoustic startle habituation, a potential biological marker for individual differences. Personality was measured using the Eysenck Personality Questionnaire (EPQ), the Sensation Seeking Scale (SSS), and Tellegen's Multidimensional Personality Questionnaire (MPQ). Higher EPQ Extraversion and higher SSS scores were associated with faster, more rapid startle habituation. Moreover, the relationship between extraversion and faster startle habituation was replicated in a second, follow-up sample. Within the initial study sample, lower scores on the Constraint (CON) factor of the MPQ (reflecting greater impulsiveness, risk-taking, and nonconformity) were also associated with faster startle habituation. Follow-up analyses revealed relationships between EPQ Extraversion, SSS, and low MPQ CON. These results suggest that faster habituation within the CNS may be associated tendencies toward impulsivity and behavioral disinhibition.