Episodic foresight deficits in regular, but not recreational, cannabis users

Altered brain structural and functional connectivity in cannabis users

Cannabis is one of the most used and commodified illicit substances worldwide, especially among young adults. The neurobiology mechanism of cannabis is yet to be identified particularly in youth. The purpose of this study was to concurrently measure alterations in brain structural and functional connectivity in cannabis users using resting-state functional magnetic resonance images (rs-fMRI) and diffusion-weighted images (DWI) from a group of 73 cannabis users (age 22-36, 19 female) in comparison with 73 healthy controls (age 22-36, 14 female) from Human Connectome Project (HCP). Several significant differences were observed in local structural/functional network measures (e.g. degree and clustering coefficient), being prominent in the insular and frontal opercular cortex and lateral/medial temporal cortex. The rich-club organization of structural networks revealed a normal trend, distributed within bilateral frontal, temporal and occipital regions. However, minor differences were found between the two groups in the superior and inferior temporal gyri. Functional rich-club nodes were mostly located within parietal and posterior areas, with minor differences between the groups found mainly in the centro-temporal and parietal regions. Regional network measures of structural/functional networks were associated with times used cannabis (TUC) in several regions. Although the structural/functional network in both groups showed small-world property, no differences between cannabis users and healthy controls were found regarding the global network measures, showing no association with cannabis use. After FDR correction, all of the significant associations between network measures and TUC were found to be insignificant, except for the association between degree and TUC within the presubiculum region. To recap, our findings revealed alterations in local topological properties of structural and functional networks in cannabis users, although their global brain network organization remained intact.

Parkinson's disease disrupts the ability to initiate and apply episodic foresight

OBJECTIVE

While Parkinson's disease is associated with impairments in many aspects of prospective cognition, no study to date has tested whether these difficulties extend to problems using episodic foresight to guide future-directed behavior. To provide the first examination of whether people with Parkinson's disease are impaired in their capacity to initiate and apply episodic foresight.

METHOD

People with Parkinson's disease (n = 42), and a demographically matched neurotypical comparison group (n = 42) completed a validated behavioral assessment that met strict criteria for assessing episodic foresight (Virtual Week-Foresight), as well as a broader neurocognitive and clinical test battery.

RESULTS

People with Parkinson's disease were significantly less likely than the comparison group to acquire items that would later allow a problem to be solved and were also less likely to subsequently use these items for problem resolution. These deficits were largely unrelated to performance on other cognitive measures or clinical characteristics of the disorder.

CONCLUSIONS

The ability to engage in episodic foresight in an adaptive way is compromised in Parkinson's disease. This appears to be a stable feature of the disorder, and one that is distinct from other clinical symptoms and neurocognitive deficits. It is now critical to establish exactly why these difficulties exist and how they impact on real-life functional capacity.

Drinking to Cope is Uniquely Associated with Less Specific and Bleaker Future Goal Generation in Young Hazardous Drinkers

Groups with mental health and/or substance use problems generate less detailed descriptions of their future goals. As substance use to cope with negative affect is common to both groups, this characteristic might be uniquely associated with less specific goal descriptions. To test this prediction, 229 past year hazardous drinking undergraduates aged 18-25 years wrote about three positive future life goals in an open-ended survey, before reporting their internalizing (anxiety and depression) symptoms, alcohol dependence severity and motivations for drinking: coping, conformity, enhancement and social. Future goal descriptions were experimenter-rated for detail specificity, and participant-self-rated for positivity, vividness, achievability, and importance. Effort in goal writing was indexed by time spent writing and total word count. Multiple regression analyses revealed that drinking to cope was uniquely associated with the production of less detailed goals, and lower self-rated positivity and vividness of goals (achievability and importance were also marginally lower), over and above internalizing symptoms, alcohol dependence severity, drinking for conformity, enhancement and social motives, age, and gender. However, drinking to cope was not uniquely associated with reduced effort in writing goals: time spent and word count. In sum, drinking to cope with negative affect is a unique characteristic predicting the generation of less detailed and bleaker (less positive and vivid) future goals, and this is not due to lower effort in reporting. Future goal generation may play a role in the aetiology of comorbidity of mental health and substance use problems, and therapeutic targeting of goal generation might benefit both conditions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10862-023-10032-0.

How do cannabis users mentally travel in time? Evidence from an fMRI study of episodic future thinking

RATIONALE

Episodic future thinking (EFT) is a cognitive function that allows individuals to imagine novel experiences that may happen in the future. Prior studies show that EFT is impaired in different groups of substance users. However, there is no evidence regarding the neurobiological mechanisms of EFT in cannabis users.

OBJECTIVES

We aimed to compare brain activations of regular cannabis users and non-using controls during an EFT fMRI task. Exploratory analyses were also conducted to investigate the association between EFT and cannabis use variables (e.g., duration of use, age onset, frequency of use).

METHODS

Twenty current cannabis users and 22 drug-naïve controls underwent an fMRI scanning session while completing a task involving envisioning future-related events and retrieval of past memories as a control condition. The EFT fMRI task was adapted from the autobiographical interview and composed of 20 auditory cue sentences (10 cues for past and 10 cues for future events). Participants were asked to recall a past or generate a future event, in response to the cues, and then rate their vividness after each response.

RESULTS

We found that cannabis users compared to non-user controls had lower activation within the cerebellum, medial and superior temporal gyrus, lateral occipital cortex, and occipital fusiform gyrus while envisioning future events. Cannabis users rated the vividness of past events significantly lower than non-users (P < 0.005). There were marginal group differences for rating the vividness of future events (P = 0.052). Significant correlations were also found between the medial and superior temporal gyrus activities and behavioral measures of EFT and episodic memory.

CONCLUSIONS

Cannabis users, compared to drug-naïve controls, have lower brain activation in EFT relevant regions. Thus, any attempts to improve aberrant EFT performance in cannabis users may benefit from EFT training.

Cannabis use and sexual risk among MSM who drink: Understanding why more frequent cannabis users may engage in higher rates of condomless sex

BACKGROUND

Condomless anal intercourse (CAI) is the major risk factor for HIV transmission among men who have sex with men (MSM). MSM who are heavier cannabis users engage in CAI more frequently. However, little is known about the processes that may underlie this association. This study sought to understand the potential role of condom attitudes and condom-related planning in the association between cannabis use and CAI.

METHODS

This is a secondary data analysis of a study on alcohol use and sexual decision-making among MSM. Two hundred and fifty-eight MSM with moderate to heavy drinking were enrolled. Measures included CAI, cannabis use, attitudes about the influence of condoms on sexual pleasure, condom use planning, age, heavy episodic drinking, and use of pre-exposure prophylaxis (PrEP).

RESULTS

We conducted a negative binomial regression analysis controlling for age, PrEP, and heavy episodic drinking. Cannabis use frequency was a significant predictor of CAI (b =.333, p < .001). Indirect effects showed that while heavier cannabis users exhibited less condom-related planning (b = -0.106, p = 0.015) and more negative attitudes toward the impact of condom use on pleasure (b= -0.177, p = 0.004), cannabis use had a significant indirect effect on CAI only through attitude ratings.

CONCLUSIONS

MSM who are heavier cannabis users engage in more frequent CAI and exhibit an indirect effect on CAI through negative attitudes toward the impact of condoms on pleasure. These findings suggest the potential importance of addressing these condom attitudes in HIV-prevention interventions among MSM who use cannabis.

Effects of episodic future thinking on reinforcement pathology during smoking cessation treatment among individuals with substance use disorders

RATIONALE

Reinforcer pathology (RP) is a theoretical model based on two processes: delay discounting (DD) and drug demand. Given that RP has been shown to have a predictive value on smoking behaviors, several studies have explored which interventions can reduce RP. Consistent with the RP framework, episodic future thinking (EFT) has shown effects on treatment outcomes and RP processes. The vast majority of studies that assess the effects of EFT on RP consist of experimental studies, and no previous research has tested these effects in a clinical sample of smokers.

OBJECTIVES

The primary aim of this study was to assess the effects of EFT on RP throughout the course of a smoking cessation intervention in smokers with substance use disorders (SUDs).

METHODS

Participants were randomized to cognitive behavior therapy (CBT) + EFT (n = 39) or CBT + EFT + contingency management (n = 33). Cotinine, frequency of EFT practices, cigarette purchase task (CPT), and DD were evaluated in treatment sessions. Mixed-effects model repeated measures analysis was used to explore DD and CPT in-treatment changes as a function of EFT practices and cotinine levels.

RESULTS

Greater practice of the EFT component significantly reduced cigarette demand (p < .020) as well as DD (p = .003). Additionally, a greater reduction in cotinine levels coupled with greater EFT practice led to a greater decrease in cigarette demand (p < .014).

CONCLUSIONS

EFT reduced the two facets of RP in treatment-seeking smokers with SUDs.

Deficits in episodic future thinking following acute alcohol consumption

RATIONALE

Acute alcohol consumption adversely affects many cognitive abilities, including episodic memory and executive functioning. However, no study to date has tested whether these acute effects of alcohol also extend to episodic future thinking (EFT). This is a surprising omission given that EFT refers to the ability to imagine oneself experiencing the future, a highly adaptive ability that has been implicated in many important functional behaviours. EFT is also thought to impose demands on episodic memory and executive control.

OBJECTIVES

The current study was designed to provide the first test of whether a moderate dose of alcohol influences EFT and whether any observed EFT difficulties are secondary to broader problems in episodic memory and executive functioning. Sex differences in EFT following acute alcohol consumption were also examined.

METHODS

One hundred and twenty-four healthy adult social drinkers were recruited and randomly assigned to either the alcohol (n = 61) or placebo (n = 63) condition. Participants were administered a dose of 0.6 g/kg alcohol or a matched placebo drink.

RESULTS

Relative to the placebo condition, EFT was impaired by acute alcohol consumption. This impairment was underpinned by broader difficulties with episodic memory, but not executive functioning. There were no sex differences in EFT performance following acute alcohol use.

CONCLUSION

These data provide novel insights into the effects of acute alcohol consumption on EFT and the broader cognitive mechanisms that contribute to these difficulties. The results are discussed in relation to their implications for understanding many of the maladaptive behaviours commonly associated with acute alcohol use.

Episodic future thinking for smoking cessation in individuals with substance use disorder: Treatment feasibility and acceptability

BACKGROUND

Smokers with substance use disorders (SUD) smoke approximately four times more than the general population. Current efforts are focused on improving smoking cessation treatments for this population. Episodic future thinking (EFT), a novel intervention aimed at decreasing impulsive choice, has shown promising results for reducing cigarette demand in experimental settings. This feasibility study sought to examine the feasibility and preliminary EFT effects on delay discounting (DD) and nicotine intake reductions throughout treatment.

METHOD

Smokers in substance use treatment (N = 29; 75.9% males) received an 8-week cognitive-behavioral treatment (CBT) + EFT for smoking cessation. The study assessed feasibility through successful recruitment rates, retention, and adherence to treatment. Participants' satisfaction acted as our acceptability measure. We computed nonparametric range tests to analyze changes in continuous variables.

RESULTS

Among interested individuals, 42 (43.75%) met the inclusion criteria, and 29 entered the treatment program. Rate of treatment completion was 65.5% (19/29). Mean (SD) sessions attended were 7(1.11), and mean patient satisfaction rating with treatment was 8.83/10. The study observed low compliance with EFT, with 15.8% (3/19) of patients practicing at least 50% of the requested times.

CONCLUSIONS

CBT + EFT is acceptable for the SUD population. However, future studies should implement some adjustments to improve the adherence and feasibility of EFT, such as reducing the number of practices and temporal intervals in EFT events. Given the small sample size, and the absence of a control group, future larger scale trials are needed to elucidate EFT effects on DD and smoking cessation.

Alcohol use disorder and cannabis use disorder symptomatology in adolescents is associated with dysfunction in neural processing of future events

Two of the most commonly used substances by adolescents in the United States are cannabis and alcohol. Cannabis use disorder (CUD) and alcohol use disorder (AUD) are associated with impairments in decision-making processes. One mechanism for impaired decision-making in these individuals is thought to be an inability to adequately represent future events during decision-making. In the current study involving 112 adolescents, we used a comparative optimism task to examine the relationship between relative severity of CUD/AUD (as indexed by the CUD/AUD Identification Tests [CUDIT/AUDIT]) and atypical function within neural systems underlying affect-based neural represenation future events. Greater CUDIT scores were negatively related to responses within subgenual anterior and posterior cingulate cortex when processing high-intensity potential future positive and negative events. There was also a particularly marked negative relationship between CUD symptoms and blood oxygen level-dependent (BOLD) responses within visual and premotor cortices to high-intensity, negatively valenced potential future events. However, AUD symptom severity was not associated with dysfunction within these brain regions. These data indicate that relative risk/severity of CUD is associated with reduced responsiveness to future high-intensity events. This may impair decision-making where future significant consequences should guide response choice.

The Behavioral Sequelae of Cannabis Use in Healthy People: A Systematic Review

Background: Cannabis is known to have a broad range of effects on behavior, including experiencing a "high" and tranquility/relaxation. However, there are several adverse behavioral sequalae that can arise from cannabis use, depending on frequency of use, potency (e.g., THC content), age of onset, and cumulative exposure. This systematic review examined evidence for cannabis-related adverse behavioral sequalae in otherwise healthy human subjects. Methods: Following PRISMA guidelines, we conducted a systematic review of cross-sectional and longitudinal studies from 1990 to 2020 that identified cannabis-related adverse behavioral outcomes in subjects without psychiatric and medical co-morbidities from PubMed and PsychInfo searches. Key search terms included "cannabis" OR "tetrahydrocannabinol" OR "cannabidiol" OR "marijuana" AND "anxiety" OR "depression" OR "psychosis" OR "schizophrenia" "OR "IQ" OR "memory" OR "attention" OR "impulsivity" OR "cognition" OR "education" OR "occupation". Results: Our search detected a total of 2,870 studies, from which we extracted 124 relevant studies from the literature on cannabis effects in the non-clinical population. Effects of cannabis on several behavioral sequelae including cognition, motivation, impulsivity, mood, anxiety, psychosis intelligence, and psychosocial functioning were identified. The preponderance of the evidence suggests that frequency of cannabis use, THC (but not CBD) content, age of onset, and cumulative cannabis exposure can all contribute to these adverse outcomes in individuals without a pre-existing medical condition or psychiatric disorder. The strongest evidence for the negative effects of cannabis are for psychosis and psychosocial functioning. Conclusions: Although more research is needed to determine risk factors for development of adverse behavioral sequelae of cannabis use, these findings underline the importance of understanding vulnerability to the adverse effects of cannabis, which has implications for prevention and treatment of problematic cannabis use.

Perceived health, medical, and psychiatric conditions in individual and dual-use of marijuana and nonprescription opioids

OBJECTIVE

Marijuana and nonprescription opioids remain the two most commonly used illicit substances in the United States. They have commonalities, yet the use of both at the same time may have a greater impact on psychological and health outcomes. Research is needed to determine whether dual-use is associated with more negative outcomes than individual substance use.

METHOD

We used the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC) Wave 1 (W1; N = 43,093), Wave 2 (W2; N = 34,653), and the more recent NESARC-III (N3; N = 36,171) to compare nonuse with use of marijuana, nonprescription opioids, or both. We examined perceived health, pain interference, pain-related medical conditions, psychiatric conditions, and suicidality.

RESULTS

Individual use and dual-use were more common in N3 than in W1. W1 dual-use and nonprescription opioid-only use predicted worse outcomes for most variables prospectively and cross-sectionally, including pain interference and poorer general health. Associations between marijuana-only use and outcomes were not as strong; however, marijuana was associated with depression and suicidal ideation.

CONCLUSION

Nonprescription opioid use is concerning with dual-use predicting poorer perceived health and pain interference with work 3 years later along with strong relationships to suicidality and psychiatric conditions. Marijuana and nonprescription opioid dual-use is a possible treatment target. Substance interventions may be enhanced by addressing alternative pain care; chronic conditions; and/or psychiatric comorbidity. Differences in outcomes between substance use and nonuse were smaller recently in N3, particularly for marijuana use only. This may be due to increased access decreasing differences between those using and not using these drugs. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Cannabis-associated impairments in the fading affect bias and autobiographical memory specificity

We investigated potential relationships between cannabis use and 2 phenomena associated with autobiographical remembering: the fading affect bias (FAB) and memory specificity. The FAB is an emotional affect regulation mechanism that is observed when the intensity of affect associated with experiencing negative memories fades faster than the intensity of affect associated with experiencing positive memories. Memory specificity refers to the level of detail with which events are recalled. No studies have examined the relationships between cannabis use, the FAB, and memory specificity simultaneously. Chronic cannabis users (N = 47) and non-users (N = 52) recalled and described positive and negative autobiographical events and rated the affective intensity for the events at the time of occurrence and at time of test. Participants retrieved additional memories using a sentence-completion recall task, which were coded for specificity. Cannabis users showed reduced fading affect for unpleasant events and reduced memory specificity compared to non-users.

Not all drugs are created equal: impaired future thinking in opiate, but not alcohol, users

Episodic future thinking refers to the ability to travel forward in time to pre-experience an event. Although future thinking has been intimately linked with self and identity, to our knowledge, no prior research has compared episodic future thinking in populations with different substance use disorders. This study investigates whether there are differences in episodic future thinking between these alcohol and opiate users. The study recruited participants who were on the opiate substitution program (n = 31) and individuals who had been diagnosed with alcohol dependence (n = 21) from the Royal Prince Alfred Hospital Drug and Health Services. Healthy controls (n = 23) were recruited via Royal Prince Alfred Hospital databases and the general community. Past and future thinking was measured using four cue words. After each cue word, participants rated their phenomenological experience (e.g. emotion, reliving experience). Results indicated that alcohol-dependent individuals performed significantly higher in episodic future thinking compared to opiate users. These findings indicate that not all substance use disorder groups share similar episodic thinking capabilities. Our results suggest that the self-projection component of rehabilitation programs may have to be tailored to the different episodic construction abilities found in substance use disorder groups.