Multimodal neuroimaging of frontal white matter microstructure in early phase schizophrenia: the impact of early adolescent cannabis use

BACKGROUND

A disturbance in connectivity between different brain regions, rather than abnormalities within the separate regions themselves, could be responsible for the clinical symptoms and cognitive dysfunctions observed in schizophrenia. White matter, which comprises axons and their myelin sheaths, provides the physical foundation for functional connectivity in the brain. Myelin sheaths are located around the axons and provide insulation through the lipid membranes of oligodendrocytes. Empirical data suggests oligodendroglial dysfunction in schizophrenia, based on findings of abnormal myelin maintenance and repair in regions of deep white matter. The aim of this in vivo neuroimaging project is to assess the impact of early adolescent onset of regular cannabis use on brain white matter tissue integrity, and to differentiate this impact from the white matter abnormalities associated with schizophrenia. The ultimate goal is to determine the liability of early adolescent use of cannabis on brain white matter, in a vulnerable brain.

METHODS/DESIGN

Young adults with schizophrenia at the early stage of the illness (less than 5 years since diagnosis) will be the focus of this project. Four magnetic resonance imaging measurements will be used to assess different cellular aspects of white matter: a) diffusion tensor imaging, b) localized proton magnetic resonance spectroscopy with a focus on the neurochemical N-acetylaspartate, c) the transverse relaxation time constants of regional tissue water, d) and of N-acetylaspartate. These four neuroimaging indices will be assessed within the same brain region of interest, that is, a large white matter fibre bundle located in the frontal region, the left superior longitudinal fasciculus.

DISCUSSION

We will expand our knowledge regarding current theoretical models of schizophrenia with a more comprehensive multimodal neuroimaging approach to studying the underlying cellular abnormalities of white matter, while taking into consideration the important confounding variable of early adolescent onset of regular cannabis use.

Mood, motives, and gambling in young adults: an examination of within- and between-person variations using experience sampling

It is well established that young adults are a population at risk for problem gambling and that young adults gamble for various reasons, including positive mood enhancement and negative mood reduction. Although these motives have been identified as important proximal predictors of gambling, the research to date has focused on between-subjects relationships. What is missing is a process-level understanding of the specific within-subjects relations between mood-regulation motives for gambling, mood states, and gambling behaviors. The current study used experience sampling to assess the specific link between gambling motives, mood states, and gambling behavior. Participants were 108 young adults (ages 19-24 years), who completed baseline measures of gambling motives and gambling problems and then reported on their mood states and gambling behavior three times a day for 30 days. Multilevel modeling analyses revealed a significant positive moderating effect for enhancement motives on the relationship between positive mood and amount of time spent gambling and number of drinks consumed while gambling. In addition, problem gambling status was associated with consuming fewer drinks while gambling at higher levels of positive mood, and spending more money than intended at higher levels of negative mood. Unexpectedly, there was only one moderating effect for coping motives on the mood-gambling relationship; low coping motivated gamblers consumed more alcohol while gambling at higher levels of positive mood, whereas high coping motivated gamblers did not change their drinking in response to positive mood. The current findings highlight enhancement motives as risky motives for young adult gambling, particularly in the context of positive mood, and suggest that gambling interventions should include strategies to address positive mood management.

Depressive symptoms are a vulnerability factor for heavy episodic drinking: a short-term, four-wave longitudinal study of undergraduate women

Heavy episodic drinking is increasingly common among undergraduate women. Cross-sectional research suggests that depressive symptoms and heavy episodic drinking are related. Nonetheless, surprisingly little is known about whether depressive symptoms are an antecedent of heavy episodic drinking, a consequence of heavy episodic drinking, or both. Such knowledge is essential to the accurate conceptualization of heavy episodic drinking, depressive symptoms, and their interrelations. In the present short-term longitudinal study, depressive symptoms and heavy episodic drinking were proposed to reciprocally influence each other over time, with depressive symptoms predicting changes in heavy episodic drinking over 1 week and vice versa. This reciprocal relations model was tested in 200 undergraduate women using a 4-wave, 4-week longitudinal design. Structural equation modeling was used to conduct cross-lagged analyses testing reciprocal relations between depressive symptoms and heavy episodic drinking. Consistent with hypotheses, both depressive symptoms and heavy episodic drinking were temporally stable, and depressive symptoms predicted changes in heavy episodic drinking over 1 week. Contrary to hypotheses, heavy episodic drinking did not predict changes in depressive symptoms over 1 week. Results are consistent with a vulnerability model suggesting depressive symptoms leave undergraduate women vulnerable to heavy episodic drinking. For undergraduate women who are struggling with feelings of sadness, worthlessness, and hopelessness, heavy episodic drinking may provide a temporary yet maladaptive means of avoiding or alleviating depressive symptoms.

The effects of alcohol on responses to nicotine-containing and denicotinized cigarettes in dependent and nondaily smokers

BACKGROUND

Alcohol consumption has been linked to increased tobacco use and craving in both dependent and nondaily smokers, yet the extent to which these relationships depend on interactions involving nicotine remains unclear. This study examined the acute effects of alcohol on the subjective and behavioral responses to nicotine-containing tobacco and denicotinized tobacco in 17 (10 male) dependent daily smokers (DDS) and 23 (11 male) nondependent nondaily smokers (NNS).

METHODS

During 4 randomized double-blind sessions, participants assessed the effects of nicotine-containing tobacco or denicotinized tobacco following the administration of a moderately intoxicating dose of alcohol (mean blood alcohol concentration = 0.076 g/dl) or a placebo beverage. They could then self-administer additional puffs of the same type of cigarette sampled over a 60-minute period using a progressive ratio task.

RESULTS

In NNS, alcohol significantly increased the self-administration of both nicotine-containing and denicotinized cigarettes, and no differences in self-administration were observed between the 2 types of tobacco within either beverage condition. In contrast, in DDS, alcohol was associated with decreased denicotinized tobacco self-administration relative to the placebo beverage condition as well as with increased self-administration of nicotine-containing tobacco relative to denicotinized tobacco. DDS also exhibited relatively elevated craving following the administration of a nicotine-containing cigarette in the alcohol beverage condition.

CONCLUSIONS

Findings suggest that nicotine may be critical to the drinking-smoking relationship in DDS, but that nonnicotine smoking factors may be more important in NNS.

Outcome expectancy liking: a self-generated, self-coded measure predicts adolescent substance use trajectories

This study tested the predictive validity of a novel, brief, and easy-to-use self-report measure of expectancies and their subjective values for alcohol and marijuana use. Canadian students in Grades 7 to 11 were administered paper-and-pencil questionnaires once per year for 3 consecutive years (Krank et al., 2011). As part of the questionnaire, participants completed an outcome expectancy measure where they were asked to list 3 or 4 things they expected would happen if they used a particular substance (i.e., alcohol, marijuana) and to indicate for each whether they would or would not like this outcome. "Liking" outcomes were coded as +1, "not like" as -1, and summed to obtain an outcome expectancy liking (OEL) sum for each participant and each substance. Participants also completed substance use behavior questions for alcohol and marijuana. Multilevel modeling demonstrated that OEL sum significantly predicted the intercept and slope of substance use trajectories by participants, even when demographic variables were controlled. For both alcohol and marijuana, multilevel modeling analyses indicated that a more positive OEL sum for a substance in the first year of the study were more likely to have tried that substance earlier (intercept) and were more likely to escalate their use at a greater rate over time (slope). The results complement the predictive validity found with other direct and indirect measures of substance use associations. The outcome expectancy liking task is a simple and unobtrusive method for identifying adolescents who are at risk for early substance abuse.

Pain is not over when the needle ends: a review and preliminary model of acute pain memory development in childhood

SUMMARY Over the past several decades, the field of pediatric pain has made impressive advances in our understanding of the pain experience of the developing child, as well as the devastating impact of inadequately managed pain early in life. It is now well recognized that, from infancy, children are capable of developing implicit memories of pain that can influence their subsequent reactions to pain. The present review provides a synthesis of selected studies that made a significant impact on this field of inquiry, with particular emphasis on recent clinical and laboratory-based experimental research examining children’s explicit autobiographical memories for acute pain. Research has begun to move towards improving the precision with which children at risk for developing negatively estimated pain memories can be identified, given the adverse influence these memories can have on subsequent pain experiences. As such, several fear- and anxiety-related child and parent variables implicated in this process are discussed, and avenues for future research and clinical intervention are identified throughout. Finally, a preliminary empirically and theoretically derived model of acute pain memory development in childhood is presented to parsimoniously summarize the evidence accumulated to date and guide future investigation in this area.

Social information processing of positive and negative hypothetical events in children with ADHD and conduct problems and controls

OBJECTIVE

This study examined social information processing (SIP) of events with varied outcomes in children with ADHD and conduct problems (CPs; defined as oppositional defiant disorder [ODD] or conduct disorder [CD]) and controls.

METHOD

Participants were 64 children (46 boys, 18 girls) aged 6 to 12, including 39 with ADHD and 25 controls. Vignettes were developed that systematically varied with regard to peer intention (ambiguous, negative, positive) and event outcome (ambiguous, negative, positive), and were used to evaluate participants' SIP abilities (cue encoding, interpretation, and response generation).

RESULTS

Results showed that, after controlling for CPs, children with ADHD detected fewer positive, negative, and neutral cues; attributed more negative and less positive intent to peers; focused less on situational outcomes of vignettes; and generated fewer positive responses compared with the control group.

CONCLUSION

These results indicate that children with ADHD differ from non-ADHD children, even after controlling for CPs, in how they process positive and negative social experiences.

Caught in a bad romance: perfectionism, conflict, and depression in romantic relationships

According to the social disconnection model, perfectionistic concerns (i.e., harsh self-scrutiny, extreme concern over mistakes and others' evaluations, and excessive reactions to perceived failures) confer vulnerability to depressive symptoms indirectly through interpersonal problems. This study tested the social disconnection model in 226 heterosexual romantic dyads using a mixed longitudinal and experience sampling design. Perfectionistic concerns were measured using three partner-specific self-report questionnaires. Conflict was measured as a dyadic variable, incorporating reports from both partners. Depressive symptoms were measured using a self-report questionnaire. Perfectionistic concerns and depressive symptoms were measured at Day 1 and Day 28. Aggregated dyadic conflict was measured with daily online questionnaires from Days 2 to 15. Data were analyzed using structural equation modeling. There were four primary findings: (a) Dyadic conflict mediated the link between perfectionistic concerns and depressive symptoms, even when controlling for baseline depressive symptoms; (b) depressive symptoms were both an antecedent and a consequence of dyadic conflict; (c) perfectionistic concerns incrementally predicted dyadic conflict and depressive symptoms beyond neuroticism (i.e., a tendency to experience negative emotions) and other-oriented perfectionism (i.e., rigidly demanding perfection from one's partner); and (d) the relationships among variables did not differ based on gender. As the most rigorous test of the social disconnection model to date, this study provides strong support for this emerging model. Results also clarify the characterological and the interpersonal context within which depressive symptoms are likely to occur.

Reformulating and testing the perfectionism model of binge eating among undergraduate women: a short-term, three-wave longitudinal study

The perfectionism model of binge eating (PMOBE) is an integrative model explaining why perfectionism is related to binge eating. This study reformulates and tests the PMOBE, with a focus on addressing limitations observed in the perfectionism and binge-eating literature. In the reformulated PMOBE, concern over mistakes is seen as a destructive aspect of perfectionism contributing to a cycle of binge eating via 4 binge-eating maintenance variables: interpersonal discrepancies, low interpersonal esteem, depressive affect, and dietary restraint. This test of the reformulated PMOBE involved 200 undergraduate women studied using a 3-wave longitudinal design. As hypothesized, concern over mistakes appears to represent a vulnerability factor for binge eating. Bootstrapped tests of mediation suggested concern over mistakes contributes to binge eating through binge-eating maintenance variables, and results supported the incremental validity of the reformulated PMOBE beyond perfectionistic strivings and neuroticism. The reformulated PMOBE also predicted binge eating, but not binge drinking, supporting the specificity of this model. The reformulated PMOBE offers a framework for understanding how key contributors to binge eating work together to generate and to maintain binge eating.

The effects of acute doses of nicotine on video lottery terminal gambling in daily smokers

RATIONALE

A growing body of evidence suggests that gambling frequently co-occurs with smoking, yet little is known about the degree to which nicotine and/or tobacco use influences gambling behavior. Nonetheless, an increasing number of studies suggest that acute administration of nicotine may alter other reinforcing behaviors in both animal and human models, raising the possibility that nicotine may also influence gambling behavior and craving.

OBJECTIVES

The purpose of this study was to examine the acute effects of nicotine on subjective and behavioral gambling responses.

METHODS

Twenty-eight (15 male) regular gamblers who smoke daily completed two double-blind laboratory sessions where their subjective and behavioral responses to video lottery terminal (VLT) gambling were assessed, following the administration of nicotine inhalers (NI; 4 mg deliverable) or placebo inhalers.

RESULTS

NI significantly decreased tobacco-related cravings (p < 0.05) but did not affect gambling-related cravings, VLT betting patterns, or subjective responses (ps > 0.1).

CONCLUSIONS

NI were found to acutely suppress tobacco-related cravings without influencing gambling. These results suggest that use of nicotine replacement therapies may be a safe option for gamblers who are attempting to quit smoking.

A comparison of gambling behavior, problem gambling indices, and reasons for gambling among smokers and nonsmokers who gamble: evidence from a provincial gambling prevalence study

INTRODUCTION

Numerous epidemiological and clinical studies have found that tobacco use and gambling frequently cooccur. Despite high rates of smoking among regular gamblers, the extent to which tobacco potentially influences gambling behavior and vice versa is poorly understood. The current study aimed to provide more insight into this relationship by directly comparing nonsmoking and smoking gamblers on gambling behavior, problem gambling indices, and reasons for gambling.

METHODS

The data for this study came from the 2005 Newfoundland and Labrador Gambling Prevalence Study. Gamblers identified as nonsmokers (N = 997) were compared with gamblers who smoke (N = 622) on numerous gambling-related variables. Chi-square analyses were used to compare groups on demographic variables. Associations between smoking status and gambling criteria were assessed with a series of binary logistic regressions.

RESULTS

The regression analyses revealed several significant associations between smoking status and past 12-month gambling. Higher problem gambling severity scores, use of alcohol/drugs while gambling, amount of money spent gambling, use of video lottery terminals, and reasons for gambling which focused on positive reinforcement/reward and negative reinforcement/relief were all associated with smoking.

CONCLUSIONS

The findings suggest an association between smoking and potentially problematic gambling in a population-based sample. More research focused on the potential reinforcing properties of tobacco on the development and treatment of problematic gambling is needed.

Posttraumatic stress hyperarousal symptoms mediate the relationship between childhood exposure to violence and subsequent alcohol misuse in Mi'kmaq youth

This study was part of a school-based collaborative research project with a Canadian Mi'kmaq community that examined the potential role of posttraumatic stress (PTS) symptom clusters in mediating the relationship between childhood exposure to violence (EV) and alcohol misuse in a sample of Mi'kmaq adolescents (N = 166). The study employed a cross-sectional design and used several well-validated self-report questionnaires. Path analytic results showed that when each PTS symptom cluster was independently investigated for mediating effects while controlling for depressive symptoms, age, and gender, only the PTS hyperarousal symptom cluster fully mediated the EV-alcohol misuse relationship. Results are discussed within the context of previous theory and research on the topic of PTS as a mediator between EV and alcohol misuse.

Drug misuse and diversion in adults prescribed anxiolytics and sedatives

STUDY OBJECTIVE

To identify patterns of misuse and diversion of anxiolytic and sedative drugs among a sample of adults prescribed these drugs.

DESIGN

Cross-sectional study.

SETTING

University research center in Canada.

PARTICIPANTS

Sixty-seven adults (aged 19-61 yrs) who had current prescriptions for anxiolytic or sedative drugs.

INTERVENTION

Face-to-face interviews and questionnaires were used to gather information on demographics as well as variables relating to drug misuse and diversion such as personality dimensions, psychiatric symptoms, and other substance use.

MEASUREMENTS AND MAIN RESULTS

Of the 67 participants, 36 (54%) reported misusing their drugs on at least one occasion, and 35 (52%) reported diverting their drugs at least once. A variety of forms of anxiolytic or sedative misuse were reported, including exceeding the recommended dosage (28 participants [42%]), deliberately using the drug with alcohol or another drug (27 [40%]), or taking it by an alternate route of administration (5 [7%]). Misuse and diversion were associated with a history of substance use and substance-related problems, as well as personality characteristics relating to impulsivity and hopelessness. Diversion was also associated with an increased likelihood of having taken any psychoactive prescription drug without having a valid prescription for it.

CONCLUSION

A variety of forms of drug misuse and diversion occurred among this population of adults who were prescribed anxiolytics or sedatives. Likelihood of engaging in misuse or diversion was associated with other substance use, substance use disorders, and personality characteristics. Despite the modest sample size and cross-sectional design, this study identified substantial heterogeneity in prescription anxiolytic and sedative misuse, suggesting that the use of clearly defined operational criteria will be essential in future efforts to further characterize this phenomenon.