Randi Melissa Schuster

Effects of cannabis on neurocognitive functioning: recent advances, neurodevelopmental influences, and sex differences.

Decades of research have examined the effects of cannabis on neurocognition. Recent advances in this field provide us with a better understanding of how cannabis use influences neurocognition both acutely (during intoxication) and non-acutely (after acute effects subside). Evidence of problems with episodic memory is one of the most consistent findings reported; however, several other neurocognitive domains appear to be adversely affected by cannabis use under various conditions. There is significant variability in findings across studies, thus a discussion of potential moderators is increasingly relevant. The purpose of this review was to 1) provide an update on research of cannabis’ acute and non-acute effects on neurocognition, with a focus on findings since 2007 and 2) suggest and discuss how neurodevelopmental issues and sex differences may influence cannabis effects on neurocognition. Finally we discuss how future investigations may lead to better understanding of the complex interplay among cannabis, stages of neurodevelopment, and sex on neurocognitive functioning.

Performance of young adult cannabis users on neurocognitive measures of impulsive behavior and their relationship to symptoms of cannabis use disorders

Recent studies suggest that abstinent cannabis users show deficits on neurocognitive laboratory tasks of impulsive behavior. But results are mixed, and less is known on the performance of non-treatment-seeking, young adult cannabis users. Importantly, relationships between performance on measures of impulsive behavior and symptoms of cannabis addiction remain relatively unexplored. We compared young adult current cannabis users (CU, n = 65) and nonusing controls (NU, n = 65) on several laboratory measures of impulsive behavior, as well as on a measure of episodic memory commonly impacted by cannabis use. The CU group performed more poorly than the NU group on the Hopkins Verbal Learning Test–Revised Total Immediate Recall and Delayed Recall. No significant differences were observed on the measures of impulsive behavior (i.e., Iowa Gambling Task, IGT; Go–Stop Task; Monetary Choice Questionnaire; Balloon Analogue Risk Task). We examined relationships between neurocognitive performance and symptoms of cannabis use disorder symptoms (Diagnostic and Statistical Manual of Mental Disorders–Fourth Edition, DSM–IV CUD) among the CU group, which revealed that poorer IGT performance was associated with more symptoms of DSM–IV CUD. Our results show poorer memory performance among young adult cannabis users than among healthy controls, but no differences on measures of impulsive behavior. However, performance on a specific type of impulsive behavior (i.e., poorer decision making) was associated with more cannabis use disorder symptoms. These results provide preliminary evidence to suggest that decision-making deficits may be more strongly associated with problems experienced from cannabis use, rather than solely being a consequence of cannabis use, per se. This publication was supported by Grants K23DA023560 and R01DA031176 (PI: Gonzalez) and F31DA032244 (PI: Schuster) from the National Institute on Drug Abuse (NIDA), as well as P01 CA098262 (PI: Mermelstein) from the National Cancer Institute (NCI). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health.

The Influence of Depression on the Progression of HIV: Direct and Indirect Effects

The authors suggest a theoretical model of pathways of HIV progression, with a focus on the contributions of depression—as well as secondary, behavioral and emotional variables. Literature was reviewed regarding (a) comorbid depression and the direct physiological effects on HIV progression and (b) intermediary factors between HIV and disease progression. Intermediary factors included (a) substance use, (b) social support, (c) hopelessness, (d) medication nonadherence, and (e) risky sexual behavior and the contraction of secondary infections. The authors suggest direct physiological pathways from depression to HIV progression and indirect pathways (e.g., behavioral, social, and psychological). In addition to depression, substance use, poor social support, hopelessness, medication nonadherence, and risky sexual behavior seem to be integral in HIV progression. Based on the individual relationships of these variables to depression and HIV progression, a comprehensive multipath model, incorporating all factors, serves to explain how severe emotional distress may lead to accelerated progression to AIDS.

Cigar, cigarillo, and little cigar use among current cigarette-smoking adolescents.

INTRODUCTION Cigar, cigarillo, and little cigar (CCLC) use is prevalent among adolescents, particularly among those who smoke cigarettes. METHODS Using data from a longitudinal study of smoking patterns among adolescents, we examined differences between CCLC users (ever and past 30 days) and nonusers (never and not in the past 30 days) among adolescents who smoked a cigarette in the last month (n = 486). RESULTS In our sample, 76.7% reported ever trying CCLC and 40.7% reported past month CCLC use. Bivariate analyses showed that CCLC users differed from nonusers in terms of demographics, other forms of tobacco use, other substance use, and mental health. Multivariate logistic regression analyses found that both ever and past 30-day CCLC use were strongly associated with being male and concurrent use of hookah. Ever CCLC use was also strongly associated with recent use of alcohol, and past 30-day CCLC use was strongly associated with antisocial behavior. After controlling for the number of days on which cigarettes were smoked in the past 30 days, past 30-day CCLC use was associated with most other forms of tobacco use, other substance use, and mental health, but not with number of cigarettes smoked in the past month and nicotine dependence. CONCLUSIONS Results suggest that CCLC use is high among adolescent cigarette users and is associated with a variety of negative correlates. Importantly, many of these relationships are not accounted for by the adolescents level of cigarette use. Further characterizing CCLC use will be important for developing more targeted and tailored interventions.

Preliminary Evidence for a Sex-Specific Relationship between Amount of Cannabis Use and Neurocognitive Performance in Young Adult Cannabis Users

Accumulating evidence suggests neuropsychological deficits from cannabis use, with a burgeoning area of preclinical research indicating possible sex-differences. However, few studies have examined how cannabis use may differentially impact neurocognition in male and female cannabis users. As such, we examined potential sex-differences in associations between amount of cannabis use (across several time frames) and neurocognitive performance among young adult regular cannabis users. Consistent with previous studies, more cannabis use was generally associated with poorer episodic memory and decision-making, but not other measures of inhibitory control. However, patterns of results suggested sex-specific dissociations. In particular, more cannabis use was more consistently associated with poorer episodic memory performance in females than males. Conversely, more cannabis use was associated with poorer decision-making performance for males, but not females. These results provide further evidence for residual cannabis-associated neurocognitive deficits and suggest the importance of examining the impact of cannabis on neurocognition separately for males and females.

The influence of inhibitory control and episodic memory on the risky sexual behavior of young adult cannabis users

Cannabis use is associated with risky sexual behavior (RSB) and sex-related negative health consequences. This investigation examined the role of inhibitory control and episodic memory in predicting RSB and sex-related negative consequences among current cannabis users. Findings indicated that the relationships among cannabis, neurocognition, and sexual-risk varied according to the dimension of neurocognition and the parameter of RSB in question. Specifically, more risk-taking was associated with more RSB. Furthermore, amount of recent cannabis use was associated with more RSB and sex-related negative consequences, but only among those with worse performances on a measure of decision-making and of risk-taking. Contrary to hypotheses, worse episodic memory also significantly predicted higher overall sexual-risk and decreased safe-sex practices. Results indicate that worse neurocognitive performance in the areas of risk-taking, decision-making, and episodic memory may influence the degree to which cannabis users engage in RSB and experience negative health consequences as a result. (JINS, 2012, 18, 1-7).

Unique roles of antisocial personality disorder and psychopathic traits in distress tolerance.

Previous research indicates that individuals with antisocial personality disorder (ASPD) evidence low distress tolerance, which signifies impaired ability to persist in goal-directed behavior during an aversive situation, and is associated with a variety of poor interpersonal and drug use outcomes. Based on theory and research indicating that psychopathic traits are associated with hypo-reactivity in emotional responding, a unique hypothesis emerges where psychopathic traits should have the opposite effect of ASPD and be related to high levels of distress tolerance. In a sample of 107 substance-dependent patients in an inner-city substance use residential treatment facility, this hypothesis was supported. ASPD was related to lower distress tolerance, while psychopathic traits were related to higher distress tolerance, with each contributing unique variance. Findings are discussed in relation to different presentations of distress tolerance as a function of psychopathic traits among those with an ASPD diagnosis.

Neuropsychological sex differences associated with age of initiated use among young adult cannabis users

Introduction. Earlier initiation of cannabis use is associated with poorer neuropsychological functioning across several domains. Given well-documented sex differences in neuromaturation during adolescence, initiation of cannabis use during this time may affect neuropsychological functioning differently for males and females. Method: In the current study, we examined sex differences in the relationship between age of initiated cannabis use and neuropsychological performance after controlling for amount of lifetime cannabis use in 44 male and 25 female young adult cannabis users. Results: We found that an earlier age of initiated use was related to poorer episodic memory, especially immediate recall, in females, but not in males. On the other hand, we found that, surprisingly, an earlier age of initiated use was associated with better decision making overall. However, exploratory analyses found sex-specific factors associated with decision making and age of initiated use, specifically that attention-deficit/hyperactivity disorder (ADHD) symptoms in females may drive the relationship between an earlier age of initiated use and better decision making. Further, an earlier age of initiated use was associated with less education, a lower IQ, and fewer years of mother’s education for females, but more lifetime cannabis use for males. Conclusions: Taken together, our findings suggest there are sex differences in the associations between age of initiated cannabis use and neuropsychological functioning. The current study provides preliminary evidence that males and females may have different neuropsychological vulnerabilities that place them at risk for initiating cannabis use and continued cannabis use, highlighting the importance of examining the impact of cannabis on neuropsychological functioning separately for males and females.

Tobacco may mask poorer episodic memory among young adult cannabis users

OBJECTIVE Co-occurring cannabis and tobacco use has become increasingly prevalent among young adults, but it is not clear how tobacco use may alter the neurocognitive profile typically observed among cannabis users. Although there is substantial evidence citing cannabis and tobaccos individual effect on episodic memory and related brain structures, few studies have examined the effect of combined cannabis and tobacco use on memory. METHOD This investigation examined relationships between amount of past year cannabis and tobacco use on 4 different indices of episodic memory among a sample of young adults who identified cannabis as their drug of choice. RESULTS Results indicated that more cannabis use was linked with poorer initial acquisition, total learning, and delayed recall on the Hopkins Verbal Learning Test-Revised, but only among cannabis users who sporadically smoked cigarettes in the past year. Conversely, the amount of past year cannabis use was not associated with episodic memory performance among individuals who more consistently smoked cigarettes in the past year. These differences could not be explained by several relevant potential confounds. CONCLUSIONS These findings provide important insight into a potential mechanism (i.e., attenuation of cognitive decrements) that might reinforce use of both substances and hamper cessation attempts among cannabis users who also smoke cigarettes. Ongoing and future research will help to better understand how co-use of cannabis and tobacco affects memory during acute intoxication and abstinence and the stability of these associations over time.

The role of decision-making in cannabis-related problems among young adults

BACKGROUND Deficits in decision-making and episodic memory are often reported among heavy cannabis users, yet little is known on how they influence negative consequences from cannabis use. Individual differences in decision-making may explain, in part, why some individuals experience significant problems from their cannabis use whereas others do not. We hypothesized that poor decision-making would moderate relationships between amount of cannabis use and problems from cannabis use whereas episodic memory performance would not. METHOD Young adult cannabis users (n=52) with cannabis as their drug of choice and with minimal comorbidities completed semi-structured interviews, self-report questionnaires, and measures of neurocognitive functioning, with decision-making accessed via the Iowa Gambling Task (IGT), episodic memory via the Hopkins Verbal Learning Test - Revised (HVLT) and problems from cannabis use with the Marijuana Problems Scale. RESULTS Strong relationships were observed between amount of cannabis use (lifetime, 12-month, and 30-day) and problems reported from use, but only among participants with low (impaired) decision-making (R(2)=.39 to .51; p<.01). No significant relationships were observed among those with better (low average to high average) decision-making performance (p>.05). In contrast, episodic memory performance was not a significant moderator of the relationship between amount of cannabis use and cannabis problems (p>.05). CONCLUSIONS Cannabis users with poor decision-making may be at greater risk for experiencing significant negative consequences from their cannabis use. Our results lend further support to emerging evidence of decision-making as a risk factor for addiction and extend these findings to cannabis users.