Juvenile ocular myasthenia gravis: a report of two cases.

We report 2 cases of pediatric ocular myasthenia gravis. The first case was a 7-year-old girl who presented with bilateral ophthalmoplegia and ptosis that correlated with the onset of upper respiratory symptoms. Neuroimaging and acetylcholine receptor antibody testing were unremarkable. The ice pack test was positive. Symptoms greatly improved with pyridostigmine, with full resolution of ophthalmoplegia achieved by 8-month follow-up. The second case was a 4-year-old girl who presented emergently with ptosis and bilateral ophthalmoplegia. Acetylcholine receptor antibodies testing was positive. The patient was started on pyridostigmine and intravenous immunoglobulin and is scheduled to follow-up with pediatric ophthalmology in the outpatient setting.

Art-delivered episodic future thinking reduces delay discounting: A phase IIa proof-of-concept trial.

INTRODUCTION: High rates of delay discounting (DD), or the preference for immediate rewards over delayed rewards, is associated with substance use disorder (SUD). Lower rates of DD predict better treatment outcomes, and thus strategies that reduce DD may support SUD recovery. The process of vividly imagining a future event, known as episodic future thinking (EFT), may be a particularly viable approach to reduce DD. Some limited research has examined delivery of EFT in treatment settings, using verbal prompts that are typical of studies in non-treatment settings. We propose that the creation of visual art represents a unique alignment of the purpose of EFT with an innovative delivery modality in treatment settings. METHODS: This single arm, proof-of-concept trial evaluated art-delivered EFT (ArtEFT) to reduce DD in a sample of women (N = 39) in a residential SUD treatment center. Participants engaged in a single, 1-h ArtEFT session during which they engaged in EFT and created a visual representation using art materials. The study collected DD measures for hypothetical money ($50 and $1000 magnitude conditions) before and after ArtEFT. RESULTS: Using area-under-the-curve (AUCord) as the index of DD, the study observed predicted changes following the ArtEFT session. The ANOVA revealed statistically significant main effects of both magnitude [F(1,38) = 11.184, p = .002] and time [F(1. 38) = 4.731, p = .036], with a non-significant interaction [F(1,38) = 3.821, p = .058]. CONCLUSION: This study reveals promising preliminary indicators that art may be an effective modality to deliver EFT, with particular advantages for implementation given the popularity of art programming in SUD treatment programs.

Engagement in types of activities and frequency of alcohol use in a national sample of United States adolescents.

OBJECTIVE: Adolescents with fewer sources of environmental reinforcement may be at risk for alcohol use. Behavioral economic theories posit that engagement in some activities may facilitate alcohol use, whereas other activities may be incompatible with use and reduce likelihood of alcohol use. It is unclear which types of activities may facilitate or may be incompatible with alcohol use in adolescence. Using a national sample of adolescents, the current study examined differences in engagement with types of activities that may be incompatible with alcohol use, compared among adolescents who endorsed alcohol use, and adolescents who did not. METHOD: Data from the 2019 Monitoring the Future (MTF) study (N = 4626) were analyzed. Potentially incompatible and facilitating activities, and alcohol-involved activities were identified from pre-existing survey measures. Confirmatory factor analysis, measurement invariance, and structural equation modeling were used to examine patterns in activity engagement among those who endorsed alcohol use and those who did not. RESULTS: Participants who did not endorse alcohol use reported higher engagement in activities that may be incompatible with alcohol use, including enjoyment from school and going to the mall (p < .001). Participants who endorsed alcohol use reported higher engagement in activities that may facilitate alcohol use (p < .001), such as spending time with friends and attending parties. Facilitating activities (ß = 0.15, p < .001) and alcohol-involved activities (ß = 0.70, p < .001) were positively associated with alcohol use frequency. Observed effect sizes were small in magnitude for all findings. CONCLUSIONS: The findings support the premise of behavioral economic theory, suggesting some activities may serve as protective factors against alcohol use frequency while other activities may facilitate alcohol use among adolescents. National surveys may consider adding specific measure of activity engagement to identify activities that may be incompatible with alcohol use among adolescents.

Engagement with Activity Monitoring During a Behavioral Activation Intervention: A Randomized Test of Monitoring Format and Qualitative Evaluation of Participant Experiences.

Behavioural activation (BA) is an efficacious treatment approach. Activity monitoring is a key component of brief BA treatments; however, no studies have examined the most efficacious format for monitoring. The present pilot study tested brief versus intensive activity monitoring approaches during a BA intervention administered in a college orientation course. Outcomes characterised (1) engagement with the treatment protocol via activity monitoring and (2) participant qualitative experiences with monitoring and the intervention as reported during focus group interviews. Four course sections were randomly assigned to receive monitoring forms that were brief (assessed activities three times daily) or intensive (assessed activities hourly). Forms were provided electronically to students via a web-based platform which tracked completion. There were no significant differences in monitoring frequency (38.0 vs. 23.0 days; p = .154) or the duration of monitoring engagement (62.0 vs. 36.0 days; p = .054) between the brief and intensive conditions. Qualitative findings suggested that participants in both conditions found utility in activity monitoring, particularly during the first month as they transitioned to college. Overall, findings indicated that participants may find utility in monitoring during the first month of a BA intervention using either brief or intensive monitoring forms.

A pilot trial of behavioural activation with a contingency management component: Preliminary examination of changes in smoking and alternative rewards among low-income individuals.

The heaviest smoking and burden of tobacco-related illness occurs among low-income individuals. Using a behavioural economics framework, this non-randomised pilot study examined the preliminary efficacy of behavioural activation (BA) with a contingency management (CM) component designed to encourage continued use of BA skills and reductions in cigarettes smoked. Eighty-four participants were recruited from a community centre. Data were collected at the start of every other group and at four different follow-up time points. Domains assessed included number of cigarettes smoked, activity level, and environmental rewards (i.e. alternative environmental reinforcers). Over time, cigarette smoking decreased (p < .001), environmental reward increased (p = .03), and reward probability and activity level were associated over time with cigarette smoking (p ≤ .03) above and beyond the effect of nicotine dependence. The continued use of BA skills was associated with greater environmental rewards (p = .04). While further research is needed to replicate this work, results suggest initial evidence for the utility of this intervention in a traditionally underserved community.

Delay discounting and substance use treatment outcomes: A systematic review focused on treatment outcomes and discounting methodology.

INTRODUCTION: Delay discounting-the tendency to choose small, immediate rewards over larger, delayed rewards-is robustly associated with substance use. Delay discounting may present challenges in treatment for substance use disorders, as individuals with elevated discounting may struggle to wait for the long-term rewards that come from abstinence, which may yield poorer treatment outcomes. However, evidence on the role of discounting in treatment outcomes has been inconsistent. The study conducted a systematic review of the literature to characterize the prospective effects of delay discounting measured pre-treatment on substance use treatment outcomes, with a focus on characterizing findings across: 1) type of treatment outcome and 2) methodology used to assess and characterize discounting. METHOD: A systematic literature search identified N = 17 studies that examined the association between delay discounting at treatment entry (pre-treatment) and substance use treatment outcomes. Findings were reported across the following substance use treatment outcomes: abstinence, relapse, use frequency and related problems, and treatment adherence. Findings regarding discounting methodology were reported by type of discounting measure (adjusting choice task, fixed choice task, or experiential task) and parameter used to characterize discounting (k, log transformed k (lnk), and area under the curve). RESULTS: Delay discounting at treatment entry was not consistently associated with substance use treatment outcomes when examined across all studies overall (47 %) or by treatment outcome (0-40 % for most outcomes). The majority of studies (64 %) that used an adjusting choice, computer-based task reported a significant association between discounting and treatment outcomes, whereas few studies that used a fixed choice or experiential task reported significant associations with treatment outcomes (0-25 %). Most studies (71 %) that used the lnk parameter to characterize discounting reported significant associations between discounting and a range of treatment outcomes. In contrast, few studies that used k or AUC (25-33 %) reported significant associations between discounting and treatment outcomes. CONCLUSION: When examined overall and by treatment outcome, evidence did not consistently indicate that delay discounting was prospectively associated with substance use treatment outcomes. However, delay discounting at treatment entry was more commonly associated with a variety of poorer treatment outcomes when researchers used more fine-grained methods to characterize discounting.

A Preliminary Experimental Study of Self-Objectification and Risky Sex Behavior Among a University Sample of Cisgender Women in the U.S.

Self-objectification is associated with a number of negative mental and behavioral outcomes. Though previous research has established associations between self-objectification and risky sex, no study to date has examined whether self-objectification affects propensity to engage in risky sex. The current research employed an experimental design to examine the effect of heightened self-objectification on a laboratory analog of risky sex (n = 181). We observed that when college-attending women experienced a heightened state of self-objectification, they were more likely to engage in sex without a condom and less likely to wait to use a condom with a highly desirable partner. Given the frequency of intended and unintended objectifying messages that young women face, this increase in willingness to engage in risky sex behavior represents a consequential health concern.

Single- and Cross-Commodity Delay Discounting of Cannabis.

OBJECTIVE: Despite extensive literature that has identified high rates of delay discounting as a behavioral correlate of substance misuse, associations of cannabis use measures and delay discounting are less consistent. Furthermore, there is very limited research examining cannabis use using cross-commodity delay discounting tasks, where the immediate and delayed outcomes are different commodities. METHOD: Using conventional single-commodity delay discounting tasks for money and cannabis outcomes as well as cross-commodity delay discounting tasks (i.e., cannabis now vs. money later, money now vs. cannabis later), we examined associations of delay discounting rates with cannabis use frequency, cannabis use disorder symptom count, cannabis-related problems, and craving among young adult cannabis users (N = 115; M age = 20.7, SD = 2.6; M cannabis use days per month = 15.5, SD = 10.0). RESULTS: Although associations between cannabis use measures and rates of delay discounting in single-commodity conditions were modest, significant associations were observed with delay discounting rates in cross-commodity conditions. Of note, regression and model comparison analyses generally showed positive associations of cannabis measures with immediate cannabis versus delayed money delay discounting rates, and negative associations of cannabis measures with immediate money versus delayed cannabis delay discounting rates. CONCLUSIONS: The results suggest that problematic cannabis use may not be strictly associated with the inability to wait for delayed outcomes, as suggested by previous research implementing single-commodity delay discounting tasks, but also with a willingness to wait for delayed access to cannabis.

Valuation of future alcohol in cross-commodity delay discounting is associated with alcohol misuse/consequences.

OBJECTIVE: Delay discounting (DD) refers to the reduction in reward value as a function of its delay, and individuals who misuse alcohol typically exhibit high rates of DD, which may reflect a general preference for immediate outcomes. This interpretation is based on studies utilizing single-commodity DD tasks where the same commodity is available immediately and following a delay. Cross-commodity DD tasks require individuals to choose between different commodities at varying delays and may provide the potential to further illuminate intertemporal preference associated with alcohol misuse. The present study examined associations between single-commodity and cross-commodity DD rates with alcohol use metrics among young adults. METHOD: DD by young adults (N = 70, aged 19-24, 71% male, 80% White) who engage in hazardous drinking was examined using a fully parametric combination of immediate and delayed alcohol and money outcomes. We hypothesized that past 30-day alcohol use and alcohol-related negative consequences would be associated with preference for alcohol outcomes independent of whether alcohol was immediate or delayed. RESULTS: Results support the hypothesis, as past 30-day consumption and AUDIT scores were positively associated with rate of DD in the immediate alcohol versus delayed money task and negatively associated with rate of DD in the immediate money versus delayed alcohol task. Moreover, we found the immediate money versus delayed alcohol task provided unique explanatory power for individual alcohol use. CONCLUSIONS: The observed associations indicate that willingness to invest in future access to alcohol may be associated with elevated alcohol use and related consequences. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The Role of Delay Discounting in the Generation of Stressful Life Events Across Adolescence.

Hammen's (1991) model of stress generation suggests that depressed individuals are more likely to behave in ways that bring about greater exposure to negative life events. More recent research suggests that adolescents with other types of psychological vulnerabilities, including those more likely to make impulsive choices, may also be predisposed to experience greater increases in stress over time. The current study examined whether delay discounting (DD), defined as the tendency to prefer smaller but immediately available rewards relative to larger, delayed rewards, predicts the generation of negative life events across adolescence and whether this is due to the association between DD and depressive symptoms. Participants (n = 213, Mage = 15, range 12-17) completed self-report measures of depressive symptoms and negative life events, as well as a behavioral measure assessing DD annually over four years. Results of latent growth models suggest that both independent and dependent negative life events increased across adolescence. Consistent with a stress generation framework, DD predicted the growth in dependent, but not independent, negative life events over this time period, controlling for baseline levels of depressive symptoms. Further exploratory analyses suggest that DD was associated with increases in depressive symptomology across adolescence, but that the relation between DD and changes in independent negative life events was not better accounted for by increases in depressive symptoms over time. Taken together, these findings suggest the importance of DD in predicting youths' exposure to dependent negative life events and point to potential avenues for clinical intervention.

Choices between money and hyper-palatable food: Choice impulsivity and eating behavior.

OBJECTIVE: Choice impulsivity may influence eating behavior. The study tested whether choice impulsivity, termed delay discounting, may be related to food generally, or may be specific to hyper-palatable foods (HPF). The study also determined whether a discounting task with choices between money and food may have utility in predicting obesity-related outcomes. METHOD: Participants (N = 284) completed a task that assessed choices between smaller reward available immediately and larger reward available later. Single commodity conditions presented choices between amounts of HPF, non-HPF, or money (e.g., HPF now vs. HPF later). Cross-commodity conditions presented choices between money and food commodities (e.g., money now vs. HPF later; money now vs. non-HPF later). RESULTS: There were no significant differences in discounting of HPF and non-HPF in single commodity conditions (Mean ln[k] difference = .40, p = .058). In the cross-commodity conditions holding money constant as the immediate reward, individuals discounted HPF significantly less than non-HPF (Mean ln[k] difference = .92; p = .0001). In regression analyses, individuals with excess HPF intake, greater HPF craving, and higher BMIs were more likely to choose HPF immediately, when money was the delayed reward (p values = .003 to .008). CONCLUSIONS: Choice impulsivity may be specific to foods that are hyper-palatable. Results suggest that individuals with excess HPF intake, higher HPF craving, and higher BMIs may exhibit a general tendency toward impulsive decision making that may be exacerbated in an obesogenic environment that provides wide access to HPF. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Social vulnerability, COVID-19 impact, and decision making among adults in a low-resource community.

Socially vulnerable individuals, including those with greater exposure to adversity and social instability, are at greater risk for a variety of negative outcomes following exposure to public health crises. One hypothesized mechanism linking social vulnerability to poor health outcomes is delay discounting, the behavioral tendency to select smaller immediately available rewards relative to larger delayed rewards. However, little research has examined the impact of real-world disease outbreaks, such as the COVID-19 pandemic, on the relation between social vulnerability and delay discounting. This study examined whether the severity of COVID-19 impact moderated the association between social vulnerability and delay discounting in a diverse sample of 72 human adults (Mage = 42.4; 69% Black; 87% female) drawn from two low-resource urban areas. Contrary to hypotheses, results indicated that exposure to more severe COVID-19 impacts did not affect decision making among individuals with higher levels of social vulnerability. Conversely, findings suggest that individuals with lower levels of social vulnerability who reported more significant impacts of COVID-19 evidenced a greater tendency to select larger, delayed rewards relative to individuals with greater social vulnerability. Findings suggest the recent pandemic may influence the relation between social vulnerability and behavioral processes underlying health decision-making.

Working Memory Training Reduces Cigarette Smoking Among Low-Income Individuals With Elevated Delay Discounting.

INTRODUCTION: The competing neurobehavioral decision systems theory conceptualizes addictive behavior, such as cigarette smoking, as arising from the imbalance between stronger impulsive relative to weaker executive decision processes. Working memory trainings may enhance executive decision processes, yet few studies have evaluated its efficacy on substance misuse, with mixed evidence. The current study is the first to evaluate the efficacy of a working memory training on cigarette smoking. We consider the moderating role of delay discounting (DD), or the preference for smaller, immediately available rewards relative to larger, delayed rewards, which has been associated with smoking onset, progression, and resumption. The investigation focuses on individuals living in high-poverty, low-resource environments due high burden of tobacco-related disease they experience. AIMS AND METHODS: The study utilized a subset of data (N = 177 individuals who smoke) generated from a randomized clinical trial that is evaluating the efficacy of working memory training for improving health-related outcomes. Participants were randomized to complete up to 15 sessions of the active, working memory training or a control training. RESULTS: Findings showed that among participants who were randomized to the working memory condition, those with higher rates of baseline DD demonstrated decreases in cigarette smoking (p = .05). Conversely, individuals randomized to the control condition, who had higher rates of baseline DD exhibited increases in cigarette smoking (p = .025). CONCLUSIONS: Results suggest that DD may be an important indicator of working memory training outcomes and a possible approach for effectively targeting treatments in the future. IMPLICATIONS: DD is important indicator of working memory training outcomes on cigarette smoking. The findings suggest the possibility to effectively target treatments considering the impact of DD. Given that rates of DD tend to be higher among individuals from low-resource communities, and that computer-based working memory training programs are relatively low-cost and scalable, these findings suggest this approach may have specific utility for adults at heightened risk for cigarette use.This study was registered with ClinicalTrials.gov (Identifier NCT03501706).

Methods to Optimize Recruitment, Participation, and Retention Among Vulnerable Individuals Participating in a Longitudinal Clinical Trial.

Low-income and ethnic/racial minority adults do not often participate in research or may face unique barriers when participating in research, which delays and impedes medical advances for this vulnerable population. This article describes in detail the evidenced-based methods used to enhance recruitment, participation, and retention in a clinical trial at a center serving ethnic/racial minorities and low-income individuals. The article details the partnership with a community outreach center and describes the duties and impact of a community liaison to enhance recruitment, participation, and retention in a randomized controlled trial with a 6-month follow-up. Of the 246 individuals initially recruited for screening, 80 did not meet inclusion criteria with the most common reason for disqualification being meeting criteria for substance use disorder (n = 44). One hundred sixty-six participants qualified for participation. The majority of participants identified as African American (n = 127, 77.1%) and reported an annual individual income under $10,000 (n = 121 (74.2%). Forty-five percent of the sample completed the requested number of sessions (i.e., 12). Sixty-three percent of participants completed post intervention assessments and 42% completed 6-month follow-up data collection. The participation and retention numbers in this study appear higher than typical participation and retention rates in longitudinal studies with similar populations. The methods and lessons learned may be useful for other clinical trials that recruit vulnerable populations and wish to enhance participation, engagement, and retention.

A review of cross-commodity delay discounting research with relevance to addiction.

Delay discounting (DD) refers to the decrease in the subjective value of a reward as the delay to its receipt increases. As high rates of DD are consistently associated with measures of substance misuse, DD is an important construct in current conceptualizations of addiction. High rates of DD appear to model preference for the immediate rewards provided by substance use, resulting in the interpretation that individuals with substance use disorder are generally unable or unwilling to delay gratification to obtain larger but delayed rewards. This interpretation is largely based on literature implementing binary choice tasks using differing amounts of the same commodity (i.e., single-commodity), in which high rates of DD can result from relative preference for the immediate outcome or relative dispreference for the delayed outcome. We propose that tasks using different commodities (i.e., cross-commodity) for the immediate and delayed outcomes offer potential in disentangling these dissociable and consequentially distinct interpretations. Our review suggests that cross-commodity DD tasks provide unique insights into understanding addiction not captured by single-commodity designs. We conclude that more research implementing cross-commodity DD tasks is needed to better understand the role of intertemporal choice in addiction and recovery.

Are You Sure: Preference and Ambivalence in Delay Discounting.

Delay discounting (DD) research has become ubiquitous due to its robust associations with clinical outcomes. Typical DD tasks involve multiple trials in which participants indicate preference between smaller, sooner and larger, later rewards. Scoring of these binary choice tasks has not considered trial-level ambivalence as a possible decision-making construct. The present study explored the extent to which trial-level ambivalence varied within-individual using an established assessment of DD (the Monetary Choice Questionnaire). Results indicate that degree of ambivalence peaks around the trials associated with the DD rate. Moreover, ambivalence is associated with a diminished impact of reward delay differences on choice, where greater delay differences decrease the odds of choosing the larger, later rewards. Taken together, we believe ambivalence to be a relevant construct for research on intertemporal decision making, and it may be particularly useful in the study of manipulations on individual rates of DD.

Exposure to maternal depressive symptoms and growth in adolescent substance use: The mediating role of delay discounting.

Maternal depression is associated with instability within the family environment and increases in offspring substance use across adolescence. Rates of delay discounting, or the tendency to select smaller rewards that are immediately available relative to larger, but delayed rewards, are also associated with steeper increases in substance use among youth. Moreover, recent research suggests that early unstable environments may reinforce youths' propensity towards opportunistic decision making and delay discounting specifically. The current prospective, longitudinal study examined links between maternal depressive symptoms, adolescent delay discounting, and subsequent substance use. Participants included 247 adolescents and their mothers who were assessed annually over a 6-year period (from ages 13 to 19 years). Results supported a small but significant mediation effect. Specifically, maternal depressive symptoms predicted increases in adolescent delay discounting, which, in turn, predicted steeper increases in adolescent substance use over time. Thus, youth decision making may represent a mechanism linking maternal depression and adolescent risk behaviors. Findings indicate the potential for interventions targeting parental psychopathology to prevent subsequent adolescent substance use.

School-based epidemiology study of myopia in Tianjin, China.

PURPOSE: To study the epidemiology of myopia in school-aged children in Tianjin and the relationship between visual acuity-based screening and refraction-based screening. METHOD: This school-based prospective cohort study was performed on children from 42 elementary schools and 17 middle schools in Tianjin, China. Totally 14,551 children, ages ranging from 5 to 16 years, were included in this study. Uncorrected visual acuity (UCVA) was determined by logarithmic tumbling E chart. Non-cycloplegic photorefraction was examined by the Spot (v2.1.4) photoscreener. The relationship between the UCVA and refractive error was investigated for different age groups. RESULTS: The overall prevalence of myopia at this school based screen is 78.2%, ranged from 10% at age of 5 to 95% at age of 16. The most dramatic increase in prevalence is from age of 6 (14.8%) to age of 7 (38.5%). The overall prevalence of high myopia is 2.5%. UCVA is found corresponding to spherical equivalent refraction (SER) in a manner of normal distribution and is significantly affected by age. When using UCVA to estimate the prevalence of myopia, the overall sensitivity and specificity are 0.824 and 0.820, respectively. Age-dependent optimal cutoff points and 95% confident intervals of such estimation are reported. CONCLUSIONS: Myopia is heavily affecting school-aged children in Tianjin, China. The refraction screening is preferable for myopia screening, whereas the UCVA screening results need to be interpreted in an age-dependent manner for myopia estimation.

Uncommitted Commitment: Behavioral Strategy to Prevent Preference Reversals.

When both smaller-sooner (SS) and larger-later (LL) rewards are temporally distal, individuals frequently prefer the LL. However, because both outcomes become proximal, individuals frequently switch to preferring the SS. These preference reversals are predicted by hyperbolic delay discounting, and may model the essential challenge of self-control. Using smokers, a population known to have high rates of delay discounting, and thus more vulnerable to preference reversals, this pilot study sought to examine soft commitment as a strategy that may prevent preference reversals. Eleven smokers were assigned to an experimental commitment condition, operationalized as 3 weeks of daily commitment trials indicating preference between an SS and LL. Ten smokers were assigned to a control commitment condition. These 3 weeks were followed by 8 days of daily choice trials indicating preference between an impending SS and LL, for both experimental and control conditions. Though no overall difference of preference was observed between groups during the choice trials, hierarchical linear modeling revealed a decrease in preference for the LL over time by the control group (e.g., increasing trend of preference reversals) but no changes by the experimental group. This pilot study provides an initial indication that soft commitment can facilitate choice persistence and prevent preference reversals.

The Indirect Effects of Trait Anxiety on Drug Use Via Emotion Dysregulation in a Low-Income Sample.

Background: Research has demonstrated consistent associations between anxiety and illicit drug use. However, few studies to date have examined the shared risk factors that may contribute to this common comorbidity. Therefore, the current investigation tested the indirect effect of trait anxiety on drug use disorder symptoms via emotion dysregulation, a widely recognized transdiagnostic risk factor found to be relevant across both anxiety and illicit drug use. Method: The sample was comprised of 241 adults (Mage = 50.56, SDage = 5.90; 76.8% Black) recruited from a community center serving low-income and homeless individuals. Results: Consistent with our hypothesis, structural equation modeling demonstrated an indirect effect of trait anxiety on drug use disorder symptoms through emotion dysregulation. Conclusions: The current findings show initial support for emotion dysregulation as an explanatory vulnerability factor indirectly underlying the relationship between anxiety and drug use.