Effects of bupropion on cognitive performance during initial tobacco abstinence

Background

Bupropion may aid tobacco abstinence by quickly relieving symptoms of nicotine withdrawal, perhaps including impaired cognitive performance. We examined whether bupropion would attenuate abstinence-induced cognitive deficits on the first day of a brief quit attempt, when smokers are most likely to relapse.

Methods

Smokers (N = 24) with high quit interest were recruited for within-subjects cross-over test of bupropion vs placebo on ability to abstain during separate short-term practice quit smoking attempts. After introduction to working memory (N-back) and sustained attention (continuous performance task; CPT) tasks during the pre-quit smoking baseline, performance on these tasks was assessed after abstaining overnight (CO < 10 ppm) on the first day of each quit attempt, while on bupropion and on placebo.

Results

Compared to placebo, bupropion after abstinence improved correct response times for working memory (p = .01 for medication by memory load interaction) and for one measure of sustained attention (numbers, but not letters; p < .05).

Discussion

Bupropion may attenuate some features of impaired cognitive performance due to withdrawal on the first day of a quit attempt. Future studies could examine whether this effect of bupropion contributes to its efficacy for longer-term smoking cessation.     

γ-Amino butyric acid and glutamate abnormalities in adolescent chronic marijuana smokers

Background

An increasing body of evidence from neuropsychological and neuroimaging studies suggests that exposure to marijuana throughout adolescence disrupts key cortical maturation processes occurring during this developmental phase. GABA-modulating pharmacologic treatments that elevate brain GABA concentration recently have been shown to decrease withdrawal symptoms and improve executive functioning in marijuana-dependent adult subjects. The goal of this study was to investigate whether the lower ACC glutamate previously reported in adolescent chronic marijuana smokers is associated with lower ACC GABA levels.

Methods

Standard and metabolite-edited proton MRS data were acquired from adolescent marijuana users (N = 13) and similarly aged non-using controls (N = 16) using a clinical 3T MRI system.

Results

The adolescent marijuana-using cohort showed significantly lower ACC GABA levels (−22%, p = 0.03), which paralleled significantly lower ACC glutamate levels (−14%, p = 0.01). Importantly, the lower ACC GABA and glutamate levels detected in the adolescent cohort remained significant after controlling for age and sex.

Conclusions

The present spectroscopic findings support functional neuroimaging data documenting cingulate dysfunction in marijuana-dependent adolescents. Glutamatergic and GABAergic abnormalities potentially underlie cingulate dysfunction in adolescent chronic marijuana users, and the opportunity for testing suitable pharmacologic treatments with a non-invasive pharmacodynamic evaluation exists.     

Cannabis use and neurocognitive functioning in a non-clinical sample of users

Objective

With the recent debates over marijuana legalization and increases in use, it is critical to examine its role in cognition. While many studies generally support the adverse acute effects of cannabis on neurocognition, the non-acute effects remain less clear. The current study used a cross-sectional design to examine relationships between recent and past cannabis use on neurocognitive functioning in a non-clinical adult sample.

Method

One hundred and fifty-eight participants were recruited through fliers distributed around local college campuses and the community. All participants completed the Brief Drug Use History Form, the Structured Clinical Interview for DSM-IV Disorders, and neurocognitive assessment, and underwent urine toxicology screening. Participants consisted of recent users (n = 68), past users (n = 41), and non-users (n = 49).

Results

Recent users demonstrated significantly (p < .05) worse performance than non-users across cognitive domains of attention/working memory (M = 42.4, SD = 16.1 vs. M = 50.5, SD = 10.2), information processing speed (M = 44.3, SD = 7.3 vs. M = 52.1, SD = 11.0), and executive functioning (M = 43.6, SD = 13.4 vs. M = 48.6, SD = 7.2). There were no statistically significant differences between recent users and past users on neurocognitive performance. Frequency of cannabis use in the last 4 weeks was negatively associated with global neurocognitive performance and all individual cognitive domains. Similarly, amount of daily cannabis use was negatively associated with global neurocognitive performance and individual cognitive domains.

Conclusions

Our results support the widespread adverse effects of cannabis use on neurocognitive functioning. Although some of these adverse effects appear to attenuate with abstinence, past users' neurocognitive functioning was consistently lower than non-users.     

Young adults who smoke cigarettes and marijuana: Analysis of thoughts and behaviors

Introduction

Smoking both cigarettes and marijuana is increasingly common among young adults, yet little is known about use patterns, motivations, or thoughts about abstinence. In a U.S. sample, this study explored young adults' severity of cigarette and marijuana co-use, quit attempts, and thoughts about use.

Methods

Young adults age 18-to-25 who had smoked at least one cigarette in the past 30 days completed an anonymous online survey.

Results

Of 1987 completed surveys, 972 participants reported both past-month cigarette and marijuana use (68% male, 71% Caucasian, mean age 20.4 years [SD = 2.0]). Frequency of use, temptations to use, measures of dependence, decisional balance, and past-year quit attempts were associated across the two substances (all p < .05), but not motivation to quit. Relative to marijuana, participants reported greater desire and a later stage of change for quitting cigarettes and were more likely to endorse a cigarette abstinence goal, yet they had lower expectancy of success with quitting cigarettes and with staying quit (all p < .001).

Conclusions

Cigarette and marijuana use, temptations to use, and pros/cons of using were related in this young adult sample. Differences in motivation and thoughts about abstinence, however, suggest that young adults may be more receptive to interventions for tobacco than marijuana use. Use patterns and cognitions for both substances should be considered in prevention and intervention efforts.     

Cognitive impairments in poly-drug ketamine users

Rationale

Cognitive impairment has been found to be reversible in people with substance abuse, particularly those using ketamine. Ketamine users are often poly-substance users. This study compared the cognitive functions of current and former ketamine users who were also abusing other psychoactive substances with those of non-users of illicit drugs as controls.

Methods

One hundred ketamine poly-drug users and 100 controls were recruited. Drug users were divided into current (n = 32) and ex-users (n = 64) according to the duration of abstinence from ketamine (> 30 days). The Beck Depression Inventory (BDI), the Hospital Anxiety Depression Scale (HADSA) and the Severity of Dependence Scale (SDS) were used to evaluate depression and anxiety symptoms and the severity of drug use, respectively. The cognitive test battery comprised verbal memory (Wechsler Memory Scale III: Logic Memory and Word List), visual memory (Rey–Osterrieth Complex Figure, ROCF), executive function (Stroop, Wisconsin Card Sorting Test, and Modified Verbal Fluency Test), working memory (Digit Span Backward), and general intelligence (Information, Arithmetic and Digit-Symbol Coding) tests.

Results

Current users had higher BDI and HADSA scores than ex-users (p < 0.001 for BDI and p = 0.022 for HADSA) and controls (p < 0.001 for BDI and p = 0.002 for HADSA). Ex-users had higher BDI (p = 0.006) but equal HADSA scores (p = 1.000) compared to controls. Both current and ex-users had lower scores on Logical Memory delayed recall (p = 0.038 for current users and p = 0.032 for ex-users) and ROCF delayed recall (p = 0.033 for current users and p = 0.014 for ex-users) than controls. Current users also performed worse on ROCF recognition than controls (p = 0.002). No difference was found between the cognitive functions of current and ex-users.

Conclusions

Ketamine poly-drug users displayed predominantly verbal and visual memory impairments, which persisted in ex-users. The interactive effect of ketamine and poly-drug use on memory needs further investigation.     

Effects of chronic ketamine use on frontal and medial temporal cognition

Background

Recreational ketamine use has been on the rise worldwide. Previous studies have demonstrated that it disrupts various memory systems, but few studies have examined how it affects learning and frontal functioning. The present study investigates the effects of repeated ketamine self-administration on frontal fluency, attention, learning, and memory along the verbal/nonverbal axis.

Methods

Twenty-five ketamine users and 30 healthy controls took a battery of neuropsychological tests. Frontal fluency was measured by the Verbal Fluency Test for semantic organization ability and the Figural Fluency Test for nonverbal executive functioning. Learning and memory were measured with the Chinese Auditory-Verbal Learning Test for acquisition and retention abilities of verbal information, as well as with the Continuous Visual Memory Test for nonverbal information. Participants also took several tests tapping subdomains of attention. To test for the potential effects of other drug use, 10 polydrug controls were included for comparison with the ketamine users and healthy controls.

Results

Ketamine users had impaired verbal fluency, cognitive processing speed, and verbal learning. Verbal learning impairment was strongly correlated with estimated lifetime ketamine use. Ketamine users showed no impairments in figural fluency, sustained attention, selective attention, visual learning, or verbal/nonverbal memory. However, heavier lifetime ketamine use was significantly correlated with deficits in verbal memory (both immediate recall and delayed recall) and visual recognition memory. Deficits in cognitive processing speed and verbal learning persisted even after polydrug controls were included in the control group, but their inclusion did make the impairment in verbal fluency barely reach statistical significance.

Conclusions

This study suggests that repeated ketamine use causes differential impairment to multiple domains of frontal and medial temporal functioning, possibly specific to verbal information processing.     

Randomized clinical trial examining duration of voucher-based reinforcement therapy for cocaine abstinence

Background

This is the first study to systematically manipulate duration of voucher-based reinforcement therapy (VBRT) to see if extending the duration increases abstinence during and following VBRT.

Methods

We randomized cocaine-dependent methadone-maintained adults to Standard (12 weeks; n = 62) or Extended (36 weeks; n = 68) VBRT and provided escalating voucher amounts contingent upon urinalysis verification of cocaine abstinence. Urinalysis was scheduled at least every 2 weeks during the 48-week study and more frequently during VBRT (3/week) and 12 weeks of Aftercare (2/week).

Results

Extended VBRT produced longer durations of continuous cocaine abstinence during weeks 1–24 (5.7 vs 2.7 weeks; p = 0.003) and proportionally more abstinence during weeks 24–36 (X² = 4.57, p = .03, OR = 2.18) compared to Standard VBRT. Duration of VBRT did not directly predict after-VBRT abstinence; but longer continuous abstinence during VBRT predicted abstinence during Aftercare (p = 0.001) and during the last 12 weeks of the study (p < 0.001). Extended VBRT averaged higher monthly voucher costs compared to Standard VBRT ($96 vs $43, p < .001); however, the average cost per week of abstinence attained was higher in the Standard group ($8.06 vs $5.88, p < .001). Participants in the Extended group with voucher costs exceeding $25 monthly averaged 20 weeks of continuous abstinence.

Conclusions

Greater abstinence occurred during Extended VBRT, but providing a longer duration was not by itself sufficient to maintain abstinence after VBRT. However, if abstinence can be captured and sustained during VBRT, then providing longer durations may help increase the continuous abstinence that predicts better long-term outcomes.     

Neurophysiological and cognitive effects of smoked marijuana in frequent users

Rationale

Previously, we reported that acute marijuana intoxication minimally affected complex cognitive performance of daily marijuana smokers. It is possible that the cognitive tests used were insensitive to marijuana-related cognitive effects.

Objectives

In the current study, electroencephalographic (EEG) signals were recorded as daily marijuana users performed additional tests of immediate working memory and delayed episodic memory, before and after smoking marijuana.

Methods

Research volunteers (N = 24), who reported smoking ∼ 24 marijuana cigarettes/week, completed this study. Participants completed baseline computerized cognitive tasks, smoked a single marijuana cigarette (0%, 1.8%, or 3.9% ?⁹-THC w/w), and completed additional cognitive tasks; sessions were separated by at least 72-hours. Cardiovascular and subjective effects were also assessed throughout sessions.

Results

Overall performance accuracy was not significantly altered by marijuana, although the drug increased response times during task performance and induced a response bias towards labeling “new” words as having been previously seen in the verbal episodic memory task. Marijuana reduced slow wave evoked potential amplitude in the episodic memory task and decreased P300 amplitude and EEG power in the alpha band in the spatial working memory task. Heart rate and “positive” subjective-effect ratings were increased in a ?⁹-THC concentration-dependent manner.

Conclusions

Relative to previous findings with infrequent marijuana users, the frequent users in the current study exhibited similar neurophysiological effects but more subtle performance effects. These data emphasize the importance of taking into account the drug-use histories of research participants and examining multiple measures when investigating marijuana-related effects on cognitive functioning.     

Mental health problems and interest in marijuana treatment among marijuana-using college students

Background

There is growing recognition that marijuana use among college students is associated with marijuana-related problems. Yet little work has examined whether use is associated with mental health problems and whether there is a dose effect such that individuals engaging in more frequent use evince relatively greater psychiatric impairments. Further, little is known about factors related to interest in marijuana treatment among students experiencing marijuana-related problems.

Method

The current study examined academic and psychiatric functioning as well as interest in marijuana treatment among undergraduates (N = 1,689). Approximately 29% acknowledged marijuana use, with 9.8% using weekly or more.

Results

More frequent marijuana use was related to more academic difficulties. Marijuana use (among both weekly and less frequent users) was related to greater psychiatric impairment. Interest in marijuana treatment was examined among students with 2+ marijuana-related problems (n = 251). Of those, 22.7% expressed interest in marijuana treatment. Factors positively related to treatment interest included: marijuana use frequency, use-related problems, friends' marijuana use, age, employment status, and some types of mental health problems.

Conclusions

Marijuana use among college students is associated with academic, psychiatric, and marijuana-related impairments. However, there is some interest in treatment to manage marijuana use among undergraduates, particularly among those with more frequent and more problematic marijuana use.     

Binge drinking trajectory and neuropsychological functioning among university students: A longitudinal study

Background

Adolescence is a time of considerable neurodevelopment. Binge drinking (BD) during this period increases the vulnerability to its neurotoxic effects. This longitudinal study aimed to investigate the relationship between BD trajectory over university years and neuropsychological functioning.

Methods

Cohort-study. Two-year follow-up. A total of 89 university students were assessed: 40 Non-BD (at Initial and Follow-up), 16 Ex-BD (BD at Initial but not at Follow-up) and 33 BD (at both times). Neuropsychological assessment of working memory, episodic memory and executive abilities was carried out during their first (Initial) and third (Follow-up) academic year at the University of Santiago de Compostela.

Results

BD subjects performed less well on the Wechsler Memory Scale-III (WMS-III) Logical Memory Subtest (immediate theme recall, P = .034; delayed theme recall, P = .037; and percent retention, P = .035) and committed more perseverative errors on the Self-Ordered Pointing Task (SOPT) (P = .021) than Non-BD. There were no differences between Ex-BD and Non-BD.

Conclusions

Binge drinking trajectory during adolescence is associated with neuropsychological performance. Persistent BD, but not Ex-BD, is associated with verbal memory and monitoring difficulties. This is compatible with the hypothesis that heavy alcohol use during adolescence may affect cognitive functions that rely on the temporomesial and dorsolateral prefrontal cortex.     

Enhancing brief cognitive-behavioral therapy with motivational enhancement techniques in cocaine users

Background

We investigated the impact of enhancing brief cognitive-behavioral therapy with motivational interviewing techniques for cocaine abuse or dependence, using a focused intervention paradigm.

Methods

Participants (n = 74) who met current criteria for cocaine abuse or dependence were randomized to three-session cognitive-behavioral therapy (CBT) or three-session enhanced CBT (MET + CBT), which included an initial session of motivational enhancement therapy (MET). Outcome measures included treatment retention, process measures (e.g., commitment to abstinence, satisfaction with treatment), and cocaine use.

Results

Participants who received the MET + CBT intervention attended more drug treatment sessions following the study interventions, reported significantly greater desire for abstinence and expectation of success, and they expected greater difficulty in maintaining abstinence compared to the CBT condition. There were no differences across treatment conditions on cocaine use.

Conclusions

These findings offer mixed support for the addition of MET as an adjunctive approach to CBT for cocaine users. In addition, the study provides evidence for the feasibility of using short-term studies to test the effects of specific treatment components or refinements on measures of therapy process and outcome.     

Binge drinking and marijuana use among menthol and non-menthol adolescent smokers: Findings from the Youth Smoking Survey

Introduction

Research has shown that smoking menthol cigarettes induces smoking initiation and hinders cessation efforts especially among youth. The objective of this paper is to examine the association between menthol cigarette smoking and substance use among adolescent students in Canada.

Methods

A nationally representative cross-sectional sample of 4466 Canadian students in grades 7 to 12 from the 2010–2011 Youth Smoking Survey is analyzed. A bivariate probit model is used jointly to examine the association of menthol smoking status with binge drinking and marijuana use.

Results

32% of the current smokers in grades 7 to 12 smoke mentholated cigarettes, 73% are binge drinkers and 79% use marijuana. Results of the bivariate probit regression analysis, controlling for other covariates, show statistically significant differences in the likelihood of binge drinking and marijuana use between menthol and non-menthol smokers. Menthol cigarette smokers are 6% (ME = 0.06, 95% CI = 0.03–0.09) more likely to binge drink and 7% (ME = 0.07, 95% CI = 0.05–0.10) more likely to use marijuana.

Conclusion

Smoking menthol cigarettes is associated with a higher likelihood of binge drinking and marijuana use among Canadian adolescents. Banning menthol in cigarettes may be beneficial to public health.     

Modulation of risk-taking in marijuana users by transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC)

Cognitive deficits that are reported in heavy marijuana users (attention, memory, affect perception, decision-making) appear to be completely reversible after a prolonged abstinence period of about 28 days. However, it remains unclear whether the reversibility of these cognitive deficits indicates that (1) chronic marijuana use is not associated with long-lasting changes in cortical networks or (2) that such changes occur but the brain adapts to and compensates for the drug-induced changes. Therefore, we examined whether chronic marijuana smokers would demonstrate a differential pattern of response in comparison to healthy volunteers on a decision-making paradigm (Risk Task) while undergoing sham or active transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC). Twenty-five chronic marijuana users who were abstinent for at least 24 h were randomly assigned to receive left anodal/right cathodal tDCS of DLPFC (n = 8), right anodal/left cathodal tDCS of DLPFC (n = 9), or sham stimulation (n = 8); results on Risk Task during sham/active tDCS were compared to healthy volunteers from a previously published dataset. Chronic marijuana users demonstrated more conservative (i.e. less risky) decision-making during sham stimulation. While right anodal stimulation of the DLPFC enhanced conservative decision-making in healthy volunteers, both right anodal and left anodal DLPFC stimulation increased the propensity for risk-taking in marijuana users. These findings reveal alterations in the decision-making neural networks among chronic marijuana users. Finally, we also assessed the effects of tDCS on marijuana craving and observed that right anodal/left cathodal tDCS of DLPFC is significantly associated with a diminished craving for marijuana.     

Latent class analysis of polysubstance use,sexual risk behaviors,and infectious disease among South African drug users

Background

HIV transmission risk among non-injection drug users is high due to the co-occurrence of drug use and sexual risk behaviors. The purpose of the current study was to identify patterns of drug use among polysubstance users within a high HIV prevalence population.

Methods

The study sample included 409 substance users from the Pretoria region of South Africa. Substances used by 20% or more the sample included: cigarettes, alcohol, marijuana and heroin in combination, marijuana and cigarettes in combination, and crack cocaine. Latent class analysis was used to identify patterns of polysubstance use based on types of drugs used. Multivariate logistic regression analyses compared classes on demographics, sexual risk behavior, and disease status.

Results

Four classes of substance use were found: MJ + Cig (40.8%), MJ + Her (30.8%), Crack (24.7%), and Low Use (3.7%). The MJ + Cig class was 6.7 times more likely to use alcohol and 3 times more likely to use drugs before/during sex with steady partners than the Crack class. The MJ + Cig class was 16 times more likely to use alcohol before/during sex with steady partners than the MJ + Her class. The Crack class was 6.1 times more likely to engage in transactional sex and less likely to use drugs before/during steady sex than the MJ + Her class.

Conclusions

Findings illustrate patterns of drug use among a polysubstance using population that differ in sexual risk behavior. Intervention strategies should address substance use, particularly smoking as a route of administration (ROA), and sexual risk behaviors that best fit this high-risk population.     

A quantitative analysis of subjective,cognitive, and physiological manifestations of the acute tobacco abstinence syndrome

Rationale

Previous studies have documented the existence of signs and symptoms of the acute tobacco abstinence syndrome; however, less attention has been paid to quantifying the magnitude of these effects.

Objective

The present study quantified the relative magnitude of subjective, cognitive, and physiological manifestations of acute tobacco abstinence.

Method

Smokers (N = 203, ≥ 15 cig/day) attended two counterbalanced laboratory sessions, one following 12-h of abstinence and the other following ad-lib smoking. At both sessions, they completed an extensive battery of self-report measures (withdrawal, affect, hunger, craving, subjective attentional bias towards smoking cues), physiological assessments (heart rate, blood pressure, brain EEG), and cognitive performance tasks (psychomotor processing, sustained attention, objective attentional bias).

Results

Abstinence effects were largest for craving, subjective attentional bias, negative affect, overall withdrawal severity, concentration difficulty, hunger, and heart rate. Effects were moderate for positive affect and EEG power. Effects were small, but reliable, for psychomotor speed, sustained attention, and somatic symptoms. Effects on performance-based indices of attentional bias towards smoking-related cues were small and reliable for some indices but not others. Effects were small and inconsistent for blood pressure and EEG frequency. Variation in internal consistency accounted for 33% of the variation in abstinence effect sizes across measures.

Conclusions

There was a wide range of effect sizes both across and within domains, indicating that the acute tobacco abstinence syndrome is not a monotonic phenomenon. These findings may be indicative of the relative magnitudes of signs and symptoms that the average smoker may exhibit during acute abstinence.     

It depends on when you ask: Motives for using marijuana assessed before versus after a marijuana use event

Background

Marijuana use motives are typically evaluated retrospectively using measures that summarize or generalize across episodes of use, which may compromise validity. Using Ecological Momentary Assessment data, we examined the main reason for a specific marijuana use event measured both prospectively and retrospectively. We then determined reason types, event characteristics, and user characteristics that predicted change in reason.

Methods

Thirty-six medical outpatients age 15 to 24 years who used marijuana two times a week or more used a handheld computer to select their main reason for use from the five categories of the Marijuana Motives Measure (Simons, Correia, & Carey, 1998) just before and after each time they used marijuana over two weeks (n = 263 events with before/after reason). The reasons were examined individually and according to dimensions identified in motivational models of substance use (positive/negative, internal/external).

Results

The reason assessed before use changed to a different reason after use for 20% of events: 10% of events for pleasure; 21%, to cope; 35%, to be more social; 55%, to expand my mind; and 100%, to conform. In the multivariable model, external and expansion reasons each predicted change in reason for use (p < 0.0001 and p = 0.001, respectively). Youth were also more likely to change their reason if older (p = 0.04), if male (p = 0.02), and with weekend use (p = 0.002).

Conclusion

Retrospective assessments of event-specific motives for marijuana use may be unreliable and therefore invalid for a substantial minority of events, particularly if use is for external or expansion reasons.     

At high risk and want to quit: Marijuana use among adults with depression or serious psychological distress

Objectives

This study compared marijuana use characteristics and quit behaviors between adults with and without depression or serious psychological distress (SPD).

Methods

Drawing data for 39,133 non-institutionalized adults from the 2011 National Survey on Drug Use and Health, we assessed marijuana use status, frequent use, dependence or abuse, and quit behaviors in association with lifetime clinician-identified depression, lifetime and recent major depressive episode (MDE), and recent SPD.

Results

Adults with depression or SPD were at a significantly higher risk of being lifetime ever users (OR = 1.60–2.08), past year users (OR = 1.67–1.86), frequent users (OR = 1.40–1.62), and dependent or abusing users (OR = 2.32–3.05) compared with adults without these symptoms. Adults with depression or SPD had a lower quit ratio overall, but were equally or even more likely to make quit or self-regulation attempts. Further analysis suggested that adults with recent MDE had the greatest level of quit attempts or self-regulation attempts compared with adults without MDE or with past MDE.

Conclusions

These findings highlight the need for tailored cessation programs to sustain quit attempts and promote successful quitting among adults with depression or SPD, especially those with recent symptoms.     

Effects of working memory load,a history of conduct disorder,and sex on decision making in substance dependent individuals

Background

Substance dependence and antisocial psychopathology, such as a history of childhood conduct disorder (HCCD), are associated with impulsive or disadvantageous decision making and reduced working memory capacity (WMC). Reducing WMC via a working memory load increases disadvantageous decision making in healthy adults, but no previous studies have examined this effect in young adults with substance dependence and HCCD.

Method

Young adults with substance dependence (SubDep; n = 158, 71 female), substance dependence and HCCD (SubDep + HCCD; n = 72, 24 female), and control participants (n = 152, 84 female) completed a test of decision making (the Iowa Gambling Task; IGT) with or without a concurrent working memory load intended to tax WMC. Outcomes were (i) net advantageous decisions on the IGT, and (ii) preferences for infrequent- versus frequent-punishment decks.

Results

SubDep + HCCD men made fewer advantageous decisions on the IGT than control men without a load, but there were no group differences among women in that condition. Load was associated with fewer advantageous decisions for SubDep + HCCD women and control men, but not for men or women in the other groups. Participants showed greater preference for infrequent-punishment, advantageous decks under load as well.

Conclusions

There are gender differences in the effects of substance dependence, HCCD, and working memory load on decision making on the IGT. Decision making by control men and SubDep + HCCD women suffered the most under load. Load increases preferences for less-frequent punishments, similar to a delay discounting effect. Future research should clarify the cognitive and neural mechanisms underlying these effects.     

Interactive effects of chronic cigarette smoking and age on hippocampal volumes

Background

Previous cross-sectional MRI studies with healthy, young-to-middle-aged adults reported no significant differences between smokers and non-smokers on total hippocampal volume. However, these studies did not specifically test for greater age-related volume loss in the total hippocampus or hippocampal subregions in smokers, and did they did not examine relationships between hippocampal and subfield volumes and episodic learning and memory performance.

Methods

Healthy, young-to-middle-aged (45 ± 12 years of age) smokers (n = 39) and non-smokers (n = 43) were compared on total hippocampal and subfield volumes derived from high-resolution 4 Tesla MRI, emphasizing testing for greater age-related volume losses in smokers. Associations between hippocampal volumes and measures of episodic learning and memory were examined.

Results

Smokers showed significantly smaller volumes, as well as greater volume loss with increasing age than non-smokers in the bilateral total hippocampus and multiple subfields. In smokers, greater pack-years were associated with smaller volumes of the total hippocampus, presubiculum, and subiculum. In the entire cohort, performance on measures of learning and memory was related to larger total hippocampal and several subfield volumes, predominately in the left hemisphere.

Conclusions

Chronic cigarette smoking in this young-to-middle aged cohort was associated with smaller total hippocampal and subfield volumes, which were exacerbated by advancing age. Findings also indicated an adverse smoking dose/duration response (i.e., pack-years) with total hippocampal and select subfield volumes. These hippocampal volume abnormalities in smokers may be related to the deficiencies in episodic learning and memory in young-to-middle-aged smokers reported in previous studies.