Differential effects of Ecstasy and cannabis on self-reports of memory ability: a web-based study

Spanish versions and validation of a series of rating scales and visual analogue scales to assess the subjective effects of cannabis

Cannabis is being legalized for medical and recreational purposes all around the world. However, the understanding of the psychological effects of cannabis is still limited, and it has been previously linked to mental disorders such as schizophrenia. Lately, new scales have been created and adapted to measure its psychological effects. The aim of this study is to create Spanish versions of some of these scales and test their psychometric characteristics. One hundred sixteen participants were recruited from Cannabis Social Clubs (CSC) in Barcelona, Spain. Participants under the effects of their own cannabis completed the Cannabis Experience Questionnaire-modified version (CEQ-mv), Addiction Research Centre Inventory-18 (ARCI-18), Psychotomimetic States Inventory (PSI) and Visual Analogue Scales (VAS). Questionnaires were completed in the CSC, providing a naturalistic setting for the study. Exploratory factor analysis and internal consistency were analyzed. PSI was reduced from a 6-factor to a 4-factor model with adequate to low reliability, ARCI-18 was reduced from a 3-factor to a 2-factor model with good reliability, and VAS were reduced from a 4-factor to a 3-factor model, also with good reliability. These questionnaires showed adequate reliability and can be used in future studies to test the subjective effects of cannabis in clinical and naturalistic settings.

Recreational drug use and prospective memory

Prospective memory (PM) impairment in recreational drug users has been documented in recent years. However, most studies on the effects of drugs on PM contain several methodological challenges, such as small sample size (< 100 participants), unrepresentative sample type (e.g., student or patient), short abstinence period (< 7 days), and lack of control of potential confounds (e.g., sleep and IQ). The present study investigated the possible consequences of recreational drug use on prospective memory, using self-report and lab-based prospective memory measures while overcoming the methodological challenges. The sample was composed of 47 non-users (27 females, age range from 18 to 50 +) and 53 drug users (21 females, age range from 18 to 50 +). Recreational drug users reported significantly more deficits in the long-term episodic, short-term habitual, and internally cued PM failures subscales of the Prospective Memory Questionnaire. However, these deficits were eliminated after controlling for covariates (e.g., age, sleep quality, general health, alcohol usage). Recreational drug users also performed worse than non-users in the short-term, long-term, event-based, and time-based PM subscales of the Royal Prince Alfred Prospective Memory Test. These results remained significant after controlling for the covariates. Drug users demonstrated greater impairments on time-based and long-term PM tasks thought to be linked with executive functioning. Taken together, the present study provides further support for recreational drug-related deficits in PM and highlights a dissociation between self-report and lab-based PM measures.

Web-Based Research in Psychology

Abstract. The present article reviews web-based research in psychology. It captures principles, learnings, and trends in several types of web-based research that show similar developments related to web technology and its major shifts (e.g., appearance of search engines, browser wars, deep web, commercialization, web services, HTML5…) as well as distinct challenges. The types of web-based research discussed are web surveys and questionnaire research, web-based tests, web experiments, Mobile Experience Sampling, and non-reactive web research, including big data. A number of web-based methods are presented and discussed that turned out to become important in research methodology. These are one-item-one-screen design, seriousness check, instruction manipulation and other attention checks, multiple site entry technique, subsampling technique, warm-up technique, and web-based measurement. Pitfalls and best practices are described then, especially regarding dropout and other non-response, recruitment of participants, and interaction between technology and psychological factors. The review concludes with a discussion of important concepts that have developed over 25 years and an outlook on future developments in web-based research.

Illegal drug use and prospective memory: A systematic review

Illegal drug use is proposed to interfere with neurobiological functioning by damaging the neurotransmitter communication systems that are believed to be responsible for cognitive abilities, including perception, attention, and memory. This review specifically examined effects of illegal drug use on prospective memory (PM) - memory for future actions. Twenty- seven studies spanning 14 years were included in this review which were divided into two broad categories based on testing methods used: self-report and lab-based testing methods. The quality of the included studies was assessed across five categories: sample type, sample size, abstinence period, testing methods and control for confounding factors. The overall quality of evidence was good for six studies and moderate for sixteen studies and low for five studies. The results from the studies employing self-report were inconsistent as illegal drug users exhibited PM deficits in some studies, but not in others. However, the studies with lab-based testing methods demonstrated more consistent findings with illegal drug users scoring worse than non-users on various PM tests. There were also consistent findings on the link between the dosage of drug taken and level of PM deficit. Based on the literature, there is moderate evidence that illegal drug use impairs PM ability. We recommend that further lab-based studies be conducted to assess dose-response effects on drug-specificity.

Effects of Alcohol Hangover on Cognitive Performance: Findings from a Field/Internet Mixed Methodology Study

Results from studies into the cognitive effects of alcohol hangover have been mixed. They also present methodological challenges, often relying on self-reports of alcohol consumption leading to hangover. The current study measured Breath Alcohol Concentration (BAC, which was obtained via breathalyzer) and self-reported drinking behavior during a night out. These were then related to hangover severity and cognitive function, measured over the internet in the same subjects, the following morning. Volunteers were breathalyzed and interviewed as they left the central entertainment district of an Australian state capital. They were provided with a unique identifier and, the following morning, logged on to a website. They completed a number of measures including an online version of the Alcohol Hangover Severity Scale (AHSS), questions regarding number and type of drinks consumed the previous night, and the eTMT-B-a validated, online analogue of the Trail Making Test B (TMT-B) of executive function and working memory. Hangover severity was significantly correlated with one measure only, namely the previous night's Breath Alcohol Concentration (r = 0.228, p = 0.019). Completion time on the eTMT-B was significantly correlated with hangover severity (r = 0.245, p = 0.012), previous night's BAC (r = 0.197, p = 0.041), and time spent dinking (r = 0.376, p < 0.001). These findings confirm that alcohol hangover negatively affects cognitive functioning and that poorer working memory and executive performance correlate with hangover severity. The results also support the utility and certain advantages of using online measures in hangover research.

The effects of licit and illicit recreational drugs on prospective memory: a meta-analytic review

RATIONALE

There are no recent reports summarising the magnitude of prospective memory (PM) impairments in recreational drug users.

OBJECTIVE

We performed a meta-analysis of studies (with a parallel group design) examining PM performance in users of common recreational drugs (including alcohol and tobacco) who were not intoxicated during testing. Studies were also evaluated for the presence of methodological bias.

METHODS

Twenty-seven studies were included in the meta-analysis following literature searches of MEDLINE, EMBASE and PsycINFO. Effect sizes (standardised mean difference; SMD) were calculated separately for the effects of alcohol, cannabis, ecstasy, methamphetamine and tobacco use. The influences of drug use and study characteristics on effect sizes were explored using meta-regressions. Sources of study bias were also assessed.

RESULTS

Heavy drinkers and regular drug users tended to perform worse than controls on event and time-based PM tasks. Effect sizes (standardised mean differences; SMDs) for event-based PM impairment across the different drug-using groups/heavy drinkers ranged between - 1.10 and - 0.49, with no 95% CI crossing 0.00. SMDs for time-based PM ranged between - 0.98 and - 0.70. Except for the CIs associated with the ES for smokers' time-based PM performance, no CIs crossed 0.00.

CONCLUSIONS

Although all drug-using groups showed moderate-large impairments in event and time-based PM, effect sizes had low precision and moderate-high levels of heterogeneity. In addition, several methodological and reporting issues were identified in the majority of studies. As such, considerable uncertainty remains regarding the role of confounds and the magnitude of PM impairments in non-intoxicated recreational drug users.

Initial feasibility and validity of a prospective memory training program in a substance use treatment population

Individuals with substance use disorders have shown deficits in the ability to implement future intentions, called prospective memory. Deficits in prospective memory and working memory, a critical underlying component of prospective memory, likely contribute to substance use treatment failures. Thus, improvement of prospective memory and working memory in substance use patients is an innovative target for intervention. We sought to develop a feasible and valid prospective memory training program that incorporates working memory training and may serve as a useful adjunct to substance use disorder treatment. We administered a single session of the novel prospective memory and working memory training program to participants (n = 22; 13 men, 9 women) enrolled in outpatient substance use disorder treatment and correlated performance to existing measures of prospective memory and working memory. Generally accurate prospective memory performance in a single session suggests feasibility in a substance use treatment population. However, training difficulty should be increased to avoid ceiling effects across repeated sessions. Consistent with existing literature, we observed superior performance on event-based relative to time-based prospective memory tasks. Performance on the prospective memory and working memory training components correlated with validated assessments of prospective memory and working memory, respectively. Correlations between novel memory training program performance and established measures suggest that our training engages appropriate cognitive processes. Further, differential event- and time-based prospective memory task performance suggests internal validity of our training. These data support the development of this intervention as an adjunctive therapy for substance use disorders. (PsycINFO Database Record

Impact of marijuana use on self-rated cognition in young adult men and women

BACKGROUND AND OBJECTIVES

Marijuana (MJ) is a widely used substance that has been shown to impair cognition in laboratory settings. There is a growing number of medical MJ dispensaries and state policies permitting the use of MJ in the United States. This study is a naturalistic study that explores the association of same day MJ use on self-rated cognition in young adult men and women.

METHODS

Forty-eight (n = 48) young adults (22 F; mean age = 22.3) participated. After a baseline assessment, participants made daily phone calls to study staff over the next 3 weeks. Cumulative minutes of MJ use in the last 24-hours were assessed. Demographic information collected and self-ratings of cognitive impairment were assessed using six questions about areas of difficulty thinking each day.

RESULTS

There was a significant relationship between greater number of minutes of MJ use and higher levels of self-rated cognitive difficulties (b = .004; SE = .001; p < .006). There was no main effect of gender (b = 1.0; SE = .81; p < .22). Planned evaluation of the interaction between gender and minutes of MJ use was not significant statistically, suggesting a similar relationship between minutes of MJ use and cognitive difficulties among women compared to men (p < .54).

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

There is an association between current and heavy MJ use and self-perceived cognitive ability in both males and females. These findings reveal important information regarding one consequence of MJ use that has real-world meaning to young adult smokers. (Am J Addict 2015;24:160-165).

Attenuation of ecstasy-induced neurotoxicity by N-acetylcysteine

Exposure to 3, 4-methylenedioxymethamphetamine (MDMA) can lead to spatial memory impairments and hippocampal cell death. Numerous evidence indicates that the antioxidant N-acetylcysteine (NAC) exerts protective effects in the brain. The present study evaluates the effects of NAC on MDMA-induced neurotoxicity.

METHODS

We intraperitoneally injected 28 adult male Sprague-Dawley rats (200-250 g) with either 0, 10 mg/kg of MDMA, or 10 mg/kg of MDMA plus 100 mg/kg of NAC. Spatial memory was assessed with a Morris Water Maze (MWM). At the end of the study, rats' brains were removed to study the structure and ultrastructure of CA1, and measure Bcl-2 and Bax expressions in the hippocampus. In the MWM, NAC treatment significantly attenuated the MDMA-induced increase in distance traveled (p < 0.05) and escape latency (p < 0.001). The decreased time spent in the target quadrant in MDMA-treated animals was attenuated by NAC (p < 0.01). NAC significantly protected against MDMA-induced apoptosis and the up- and down-regulation of Bax and Bcl-2, respectively. These data have suggested that NAC could protect against behavioral changes and apoptosis in the hippocampus following administration of MDMA. NAC might be useful for the treatment of neurotoxicity in MDMA users.

Prospective memory impairment in long-term opiate users

RATIONALE

Opiate use is associated with a range of neurological and cognitive deficits. However, to date, no studies have assessed whether these cognitive deficits extend to the ability to perform intended actions in the future (i.e. prospective memory). Reduced ability in this area might be anticipated due to impaired executive functions and episodic memory associated with long-term opiate use.

OBJECTIVES

The main objectives of this study are to assess the performance of long-term opiate users on a laboratory measure of prospective memory which closely simulates the types of prospective memory tasks encountered in everyday life ('Virtual Week') and to investigate the extent to which prospective memory performance is related to executive functions and episodic memory ability.

METHODS

Twenty-six long-term heroin users enrolled in an opiate substitution program, and 30 controls with no previous history of drug use were tested on Virtual Week. Retrospective memory and executive functions were also assessed.

RESULTS

Long-term opiate users were significantly impaired on prospective memory performance compared with controls (p = 0.002, η(2) p = 0.17), and these deficits did not vary as a function of prospective memory task type (regular, irregular, event, time). The findings also suggest that retrospective memory difficulties contribute to the prospective memory difficulties seen in opiate users (r s  = 0.78, p < 0.001) but that executive dysfunction is less influential.

CONCLUSIONS

Prospective memory is sensitive to long-term opiate use. Importantly, opiate users suffer from generalised deficits in prospective memory, regardless of the task demands, which may have significant implications for day-to-day functioning. These results may therefore contribute to the development of clinical intervention strategies to reduce the negative impact of prospective memory failures in daily life.

Male and female ecstasy users: differences in patterns of use, sleep quality and mental health outcomes

BACKGROUND

Ecstasy users report a number of adverse effects following use including mood and sleep disturbances. The present study examined differences in characteristics of ecstasy use (amount, frequency of use, reported harm resulting from use) between males and females and assessed relationships between ecstasy use, sleep quality and mental health outcomes.

METHODS

An online survey of 268 ecstasy users (54.1% male, 45.9% female) was conducted. Validated sleep instruments assessing sleep quality and excessive daytime sleepiness, as well as questionnaires regarding physical and mental health (measured using the short-form health survey 12 (SF-12) and details of drug use were included.

RESULTS

Male ecstasy users reported taking larger amounts of ecstasy, but were not more frequent users compared to females. Female ecstasy users were more likely to report increased harm following ecstasy including: feelings of guilt and remorse; failing to do what was normally expected of them; and having been told by others to cut down their ecstasy use. There were interactions between amount and gender and frequency and gender in predicting use of sleep medication and daytime dysfunction. There was a positive correlation between poorer sleep quality and negative mood, although this relationship was not moderated by sex.

CONCLUSIONS

There is a significant association between sleep quality and mood disturbance in ecstasy users suggesting that these negative outcomes are co-morbid. These findings have implications for the treatment and advice given to ecstasy users who are experiencing sleep and/or mood related complaints.

Mechanisms underlying the link between cannabis use and prospective memory

While the effects of cannabis use on retrospective memory have been extensively examined, only a limited number of studies have focused on the links between cannabis use and prospective memory. We conducted two studies to examine the links between cannabis use and both time-based and event-based prospective memory as well as potential mechanisms underlying these links. For the first study, 805 students completed an online survey designed to assess cannabis consumption, problems with cannabis use indicative of a disorder, and frequency of experiencing prospective memory failures. The results showed small to moderate sized correlations between cannabis consumption, problems with cannabis use, and prospective memory. However, a series of mediation analyses revealed that correlations between problems with cannabis use and prospective memory were driven by self-reported problems with retrospective memory. For the second study, 48 non-users (who had never used cannabis), 48 experimenters (who had used cannabis five or fewer times in their lives), and 48 chronic users (who had used cannabis at least three times a week for one year) were administered three objective prospective memory tests and three self-report measures of prospective memory. The results revealed no objective deficits in prospective memory associated with chronic cannabis use. In contrast, chronic cannabis users reported experiencing more internally-cued prospective memory failures. Subsequent analyses revealed that this effect was driven by self-reported problems with retrospective memory as well as by use of alcohol and other drugs. Although our samples were not fully characterized with respect to variables such as neurological disorders and family history of substance use disorders, leaving open the possibility that these variables may play a role in the detected relationships, the present findings indicate that cannabis use has a modest effect on self-reported problems with prospective memory, with a primary problem with retrospective memory appearing to underlie this relationship.

Cannabis-related deficits in real-world memory

BACKGROUND

Research shows that cannabis users exhibit deficits in prospective memory (PM) and executive function, which persist beyond acute intoxication. However, many studies rely on self-reports of memory failures or use laboratory-based measures that may not mimic functional deficits in the real world. The present study aimed to assess real-world memory functioning.

METHOD

Twenty cannabis-only users and 20 non-illicit drug users were recruited. Participants completed a substance use inventory and a mood scale, followed by a non-immersive virtual reality task assessing PM and executive functioning. The task involved the participant playing the role of an office worker for the day and performing routine office duties. A number of subscales were used to assess facets of executive function (planning, adaptive thinking, creative thinking, selection, prioritisation) and PM (time-based, event-based and action-based PM).

RESULTS

Multivariate analysis of variance revealed cannabis users performed worse overall on the task, with poor performance on the planning, time-based PM and event-based PM subscales. In addition, indices of cannabis (length, dose, frequency, total use) were correlated with performance on these three subscales.

CONCLUSIONS

The present study expands on previously established research, providing support for the cannabis-related deficits in PM and executive functioning, and the role of different aspects of cannabis use in these deficits.

The effects of multitasking on psychological stress reactivity in recreational users of cannabis and MDMA

BACKGROUND

Cannabis and 3,4-methylenedioxymethamphetamine (MDMA) use is associated with psychobiological and neurocognitive deficits. Assessments of the latter typically include tests of memory and everyday cognitive functioning. However, to date, little attention has been paid to effects of drug use on psychological stress reactivity. We report three studies examining the effects of recreational use of cannabis and MDMA on mood and psychological responses to multitasking using a cognitively demanding laboratory stressor that provides an analogue for everyday situations involving responses to multiple stimuli.

METHODS

The effects of the multitasking framework on mood and perceived workload were assessed in cannabis (N=25), younger (N=18) and older (N=20) MDMA users and compared with non-target drug controls.

RESULTS

Compared with respective control groups, cannabis users became less alert and content, and both MDMA groups became less calm following acute stress. Unexpectedly, the stressor increased ratings of calm in cannabis users. Users also scored higher than their controls with respect to ratings of resources needed to complete the multitasking framework.

CONCLUSIONS

These findings show, for the first time, that recreational use of cannabis and MDMA, beyond the period of intoxication, can negatively influence psychological responses to a multitasking stressor, and this may have implications for real-life situations which place high demands on cognitive resources.

Prospective memory deficits in Ecstasy users: effects of longer ongoing task delay interval

Ecstasy use has been associated with neurotoxicity and neurocognitive impairment in a variety of domains, including prospective memory (ProM), which involves the delayed execution of a previously encoded intention in response to a specific cue. The present study adopted the multiprocess theory of ProM to evaluate the hypothesis that Ecstasy users would evidence differentially impaired ProM on longer versus shorter ongoing task delays. Ecstasy (n = 31) users, high-risk alcohol users (n = 21), and healthy nonusers (n = 31) completed the short (2-min) and long (15-min) delay ProM scales of the Memory for Intentions Screening Test. Results showed a significant group by ProM delay interaction, such that Ecstasy users performed comparably to the comparison groups on short-delay trials, but were impaired on long-delay ProM, particularly for time-based cues. Among the Ecstasy users, long-delay ProM was positively associated with risky decision making, but not with retrospective memory or other aspects of executive functions. These findings suggest that Ecstasy users may be particularly susceptible to deficits in strategic target monitoring and maintenance of cue-intention pairings over longer ProM delays. Findings are discussed in the context of their potential everyday functioning (e.g., academic, vocational) and treatment implications for Ecstasy users.

Ecstasy use and self-reported disturbances in sleep

OBJECTIVE

Ecstasy users report a number of complaints after its use including disturbed sleep. However, little is known regarding which attributes of ecstasy use are associated with sleep disturbances, which domains of sleep are affected or which factors may predict those ecstasy users likely to have poor sleep quality and/or excessive daytime sleepiness.

METHODS

This study examined questionnaire responses of social drug users (n = 395) to the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale.

RESULTS

A significant proportion of ecstasy users (69.5%) had Pittsburgh Sleep Quality Index scores above the threshold used to identify sleep disturbance. Although frequency of ecstasy use did not affect the degree of reported sleep disturbance, participants who used larger amounts of ecstasy had poorer sleep. In addition, participants who perceived harmful consequences arising from their ecstasy use or had experienced remorse following ecstasy use had poorer sleep. Clinically relevant levels of sleep disturbance were still evident after controlling for polydrug use. Risk factors for poor sleep quality were younger age, injury post-ecstasy use and having been told to cut down on ecstasy use.

CONCLUSIONS

Many ecstasy users report poor sleep quality, which likely contributes to the negative effects reported following ecstasy use.

Prospective memory functioning among ecstasy/polydrug users: evidence from the Cambridge Prospective Memory Test (CAMPROMPT)

RATIONALE

Prospective memory (PM) deficits in recreational drug users have been documented in recent years. However, the assessment of PM has largely been restricted to self-reported measures that fail to capture the distinction between event-based and time-based PM. The aim of the present study is to address this limitation.

OBJECTIVES

Extending our previous research, we augmented the range laboratory measures of PM by employing the CAMPROMPT test battery to investigate the impact of illicit drug use on prospective remembering in a sample of cannabis only, ecstasy/polydrug and non-users of illicit drugs, separating event and time-based PM performance. We also administered measures of executive function and retrospective memory in order to establish whether ecstasy/polydrug deficits in PM were mediated by group differences in these processes.

RESULTS

Ecstasy/polydrug users performed significantly worse on both event and time-based prospective memory tasks in comparison to both cannabis only and non-user groups. Furthermore, it was found that across the whole sample, better retrospective memory and executive functioning was associated with superior PM performance. Nevertheless, this association did not mediate the drug-related effects that were observed. Consistent with our previous study, recreational use of cocaine was linked to PM deficits.

CONCLUSIONS

PM deficits have again been found among ecstasy/polydrug users, which appear to be unrelated to group differences in executive function and retrospective memory. However, the possibility that these are attributable to cocaine use cannot be excluded.

Everyday and prospective memory deficits in ecstasy/polydrug users

The impact of ecstasy/polydrug use on real-world memory (i.e. everyday memory, cognitive failures and prospective memory [PM]) was investigated in a sample of 42 ecstasy/polydrug users and 31 non-ecstasy users. Laboratory-based PM tasks were administered along with self-reported measures of PM to test whether any ecstasy/polydrug-related impairment on the different aspects of PM was present. Self-reported measures of everyday memory and cognitive failures were also administered. Ecstasy/polydrug associated deficits were observed on both laboratory and self-reported measures of PM and everyday memory. The present study extends previous research by demonstrating that deficits in PM are real and cannot be simply attributed to self-misperceptions. The deficits observed reflect some general capacity underpinning both time- and event-based PM contexts and are not task specific. Among this group of ecstasy/polydrug users recreational use of cocaine was also prominently associated with PM deficits. Further research might explore the differential effects of individual illicit drugs on real-world memory.

Smoking and everyday prospective memory: a comparison of self-report and objective methodologies

AIMS

To examine whether persistent smoking leads to impairments in self-reported and objective measures of prospective memory (PM: the cognitive ability to remember to carry out activities at some future point in time).

METHODS

An opportunity sample of 18 existing smokers and 22 who had never smoked were compared. An existing-groups design was utilised, comparing a smoking group with a never-smoked control group as the independent factor. Scores on the sub-scales of the Prospective and Retrospective Memory Questionnaire (PRMQ) and scores on the Cambridge Prospective Memory Test (CAMPROMPT) constituted the dependent factors. Age, mood, other drug use, strategy scores and IQ were also measured. Each participant was tested in a laboratory setting. Self-reported PM lapses were measured using the PRMQ. The CAMPROMPT was used as an objective measure of PM. Alcohol and other drug use were assessed by a Recreational Drug Use Questionnaire. The Hospital Anxiety and Depression Scale gauged levels of anxiety and depression. A strategy scale measured the number of strategies used to aid memory. The National Adult Reading Test measured IQ.

RESULTS

After observing no between-group differences on age, mood, alcohol use, strategy use, and IQ, smokers and the never-smoked did not differ on the self-reported lapses measured on the PRMQ. However, smokers recalled significantly fewer items on the CAMPROMPT than the never-smoked group.

CONCLUSION

The results of the present study suggest that persistent smoking leads to impairments in everyday PM.

Using the internet to research hidden populations of illicit drug users: a review

AIMS

To review the current research of hidden populations of illicit drugs users using web-based methods and discuss major advantages and disadvantages.

METHODS

Systematic review of 16 databases, including PubMed, PsycINFO (EBSCOhost), CSA Sociological Abstracts, Expanded Academic ASAP and Google Scholar.

FINDINGS

Substances researched were most commonly 'party/club drugs' (such as ecstasy) and cannabis. All of the studies reviewed concluded that the internet is a useful tool for reaching hidden populations, but is likely to impose some bias in samples. Advantages include: access to previously under-researched target groups; speed; international applications; increased ease of data entry; and improved confidentiality for respondents. The major disadvantage is a lack of representativeness of samples.

CONCLUSIONS

Internet research is successful at accessing hidden populations of illicit drugs users, when appropriately targeted and provides unprecedented opportunities for research across a wide range of topics within the addictions field. Findings are unlikely to be generalisable to the general public, but appropriate for describing target populations.

Does cannabis use affect prospective memory in young adults?

The aim of the present study was to examine prospective memory impairments associated with cannabis use in young adults. An independent measures design utilising pre-existing groups of users and non-users was employed in which an opportunity sample of 90 undergraduates studying at universities in the north east of England participated. The number of prospective memory failures reported on the Prospective Memory Questionnaire and the number of location-action combinations correctly recalled during a video-based prospective memory task were measured. The number of strategies used to assist memory, level of anxiety and depression, and use of alcohol, nicotine and any other recreational drugs in addition to cannabis were also measured and controlled during the analysis. Analysis revealed no significant differences in the number of self-reported prospective memory failures; however, cannabis users recalled significantly fewer location-action combinations than non-users in the video-based prospective memory task. The findings from the present study suggest that cannabis use has a detrimental effect on prospective memory ability in young adults but users may not be aware of these deficits.

Reduced memory and attention performance in a population-based sample of young adults with a moderate lifetime use of cannabis, ecstasy and alcohol

Regular use of illegal drugs is suspected to cause cognitive impairments. Two substances have received heightened attention: 3,4-methylenedioxymethamphetamine (MDMA or 'ecstasy') and delta-9-tetrahydrocannabinol (THC or 'cannabis'). Preclinical evidence, as well as human studies examining regular ecstasy consumers, indicated that ecstasy use may have negative effects on learning, verbal memory and complex attentional functions. Cannabis has also been linked to symptoms of inattention and deficits in learning and memory. Most of the published studies in this field of research recruited participants by means of newspaper advertisements or by using word-of-mouth strategies. Because participants were usually aware that their drug use was critical to the research design, this awareness may have caused selection bias or created expectation effects. Focussing on attention and memory, this study aimed to assess cognitive functioning in a community-based representative sample that was derived from a large-scale epidemiological study. Available data concerning drug use history allowed sampling of subjects with varying degrees of lifetime drug experiences. Cognitive functioning was examined in 284 young participants, between 22 and 34 years. In general, their lifetime drug experience was moderate. Participants completed a neuropsychological test battery, including measures for verbal learning, memory and various attentional functions. Linear regression analysis was performed to investigate the relationship between cognitive functioning and lifetime experience of drug use. Ecstasy and cannabis use were significantly related to poorer episodic memory function in a dose-related manner. For attentional measures, decrements of small effect sizes were found. Error measures in tonic and phasic alertness tasks, selective attention task and vigilance showed small but significant effects, suggesting a stronger tendency to experience lapses of attention. No indication for differences in reaction time was found. The results are consistent with decrements of memory and attentional performance described in previous studies. These effects are relatively small; however, it must be kept in mind that this study focussed on assessing young adults with moderate drug use from a population-based study.

Involvement of inferior parietal lobules in prospective memory impairment during acute MDMA (ecstasy) intoxication: an event-related fMRI study

Prospective memory refers to the realization of delayed intentions. Several studies have shown that 3,4-methylenedioxy-methamphetamine (MDMA) users perform worse on measures of prospective memory as compared to nondrug users. Interpretation of these data may be limited because of polydrug use, psychosocial stressors, and increased psychopathology that have been reported in MDMA users. This study was designed to directly assess the pharmacological effect of MDMA on prospective memory and brain activity in a double-blind, placebo-controlled, cross-over study. Twelve recreational MDMA users received MDMA 75 mg and placebo and performed an objective prospective memory task during functional imaging. During prospective memory task performance subjects were engaged in a foreground task that consisted of a simple reaction time to visual stimuli (Go trials) and a prospective task of withholding a response during trials that were part of a dynamic memory set (No go trials). Behavioral data showed that a single dose of MDMA increased prospective memory failures in the No go trials, and that number of prospective memory failures was positively correlated to MDMA concentration in plasma. Functional imaging showed that MDMA decreased BOLD activation during Go trials in the thalamus (left), putamen (left), precuneus (left), and the inferior parietal lobules (bilateral), as compared to placebo. During No go trials, MDMA reduced BOLD deactivation in the inferior parietal lobules (bilateral), as compared to placebo. It is concluded that the loss of deactivation in inferior parietal lobules may account for increments in memory failures observed during MDMA intoxication.

A pilot study using the internet to study patterns of party drug use: processes, findings and limitations

Since the 1990s there has been a rise in both the prevalence of party drug use in Australia and the use of party drug-related websites. This study investigates whether it is feasible to recruit and survey party drug users via the internet. It took place in Victoria, Australia. Participants were directed to a website where they completed a brief, structured internet-based survey. A total of 460 responses were received over 31 days, 393 of which fitted all inclusion criteria. The sample consisted predominately of young, male polydrug users and is one of the largest samples of party drug users in Australia reported thus far. It was concluded that it is feasible to recruit and survey current party drug users via the internet and that this method is quicker and cheaper than traditional survey methods, although samples are not necessarily representative of the party drug-using population. Other limitations and advantages are discussed.

Recreational ecstasy use and the neurotoxic potential of MDMA: current status of the controversy and methodological issues

The controversy over possible MDMA-induced serotonergic neurotoxicity in human recreational ecstasy users is examined critically in light of recent research findings. Although the designs of such studies have improved considerably since the 1990s, the evidence to date remains equivocal for a number of reasons, including (1) inconsistent findings on the existence and reversibility of persistent ecstasy-related serotonergic and cognitive deficits; (2) lack of clear association between changes in brain imaging measures and functional deficits attributed to MDMA-induced neurotoxicity; (3) the contribution of concomitant cannabis or other drug use to both brain imaging abnormalities and cognitive deficits; (4) methodological shortcomings such as failure to adequately match samples of ecstasy users and controls; (5) the questionable relevance of animal models of MDMA-induced neurotoxicity to typical human patterns of ecstasy use; and (6) the potential role of inherent pre-drug deficits in serotonergic systems, impulse control and executive cognitive function that may predispose to excessive use of drugs including ecstasy. Given the retrospective nature of nearly all studies of ecstasy users to date, the controversy over whether MDMA has ever caused neurotoxicity or cognitive deficit in human ecstasy users is likely to continue for some time without resolution.

Prospective memory impairment in former users of methamphetamine

RATIONALE

Considerable research indicates that methamphetamine use is associated with neurocognitive impairment, but no empirical study to date has assessed whether these difficulties extend to memory for future intentions (prospective memory).

OBJECTIVES

The present study assessed prospective performance on a laboratory measure of prospective memory that closely represents the types of prospective memory tasks that actually occur in everyday life and provides an opportunity to investigate the different sorts of prospective memory failures that occur ("Virtual Week").

MATERIALS AND METHODS

Twenty adults with confirmed history of methamphetamine use and dependence, currently engaged in rehabilitation and confirmed to be abstinent for an average period of 6 months, and 20 methamphetamine-naive participants were tested on Virtual Week. Various other aspects of cognitive function were also assessed, including retrospective memory and executive functioning.

RESULTS

Methamphetamine users were significantly impaired on Virtual Week, and these deficits did not vary as a function of specific prospective memory task demands. Of all the cognitive measures, cognitive inhibition shared greatest variance with group effects on the prospective memory measure.

CONCLUSIONS

Prospective memory performance is sensitive to prior methamphetamine use even well into abstinence. Methamphetamine users experience generalized difficulties with prospective memory, suggesting that these deficits are likely to have important implications for day-to-day functioning.

Polydrug use, cannabis, and psychosis-like symptoms

OBJECTIVE

To examine psychosis-like symptoms in users of legal and illicit drugs.

METHODS

Schizotypal Personality Questionnaire (SPQ) scores were compared in groups of people with different exposure to cannabis, with the use of other drugs serving as a covariate. Supplemental analyses compared users of legal and illicit drugs with cannabis use as a covariate.

RESULTS

Weekly (n = 111) and monthly (n = 136) cannabis users had higher scores on the SPQ than former (n = 143) and non-users (n = 81). The use of other drugs accounted for the links between cannabis and schizotypy. Lifetime use of psychomotor stimulant drugs plus ecstasy accounted for associations between cannabis and scores on the SPQ and its different subscales. Dividing groups by type of drug use revealed that those who used only cannabis and legal drugs (CLDs) (n = 126) were no different from those who used only legal drugs (LDs) (n = 74) but both groups scored significantly lower on the SPQ than polydrug users (n = 247). When controlling for marijuana use in the last month, the significant difference across drug use groups remained.

CONCLUSIONS

The results suggest that research on marijuana and schizotypy requires careful assessment of the use of other drugs, especially psychomotor stimulants and ecstasy.

Metamemory in recreational ecstasy polydrug users: what do self-reports of memory failures mean?

Previous research has found relationships between self-rated memory and ecstasy use, such that heavier users report worse function. These findings have been interpreted in terms of objective memory capacity. However, research on metamemory suggests that self-reported memory may be only weakly related to objective function, with demographics, mood, and memory-related beliefs and feelings also contributing to ratings. This study examined relationships between ecstasy/other drug use and self-reported memory, controlling for effects of demographic factors and mood. Associations between self-reported memory, memory-related beliefs and feelings, and objectively-measured cognitive function were also examined. Forty-five ecstasy polydrug, 48 cannabis polydrug, and 40 legal drug users completed a battery of neuropsychological tests and questionnaire measures of metamemory, including memory-related control beliefs, memory-related anxiety, and self-reported prospective and general/retrospective memory. The combined polydrug groups reported more general/retrospective memory failures. Covariance analysis, however, suggested that this finding was confounded by general anxiety levels. A combination of objective cognitive measures contributed to prediction of self-rated prospective memory, with demographics, mood, and memory-related anxiety also contributing to variability. However, associations between objective and self-reported memory were not strong. Self-report may not be a specific methodology with which to assess objective memory capacities in ecstasy and other drug users.

Real-world memory and executive processes in cannabis users and non-users

The relationships between executive processes, associative learning and different aspects of real world memory functioning were explored in a sample of cannabis users and nonusers. Measures of executive component processes, associative learning, everyday memory, prospective memory, and cognitive failures were administered. Relative to nonusers, cannabis users were found to be impaired in several aspects of real world memory functioning. No other group differences were apparent. The absence of cannabis related deficits in those executive component processes and aspects of learning that are believed to support real world memory processes is surprising given that cannabis related deficits were obtained in real world memory. The present results are discussed within the context of neuroimaging evidence which suggests that cannabis users may exhibit different patterns of neural activation when performing executive tasks while not always exhibiting deficits on these tasks.

Executive function deficits in short-term abstinent cannabis users

OBJECTIVES

Few cognitive tasks are adequately sensitive to show the small decrements in performance in abstinent chronic cannabis users. In this series of three experiments we set out to demonstrate a variety of tasks that are sufficiently sensitive to show differences in visual memory, verbal memory, everyday memory and executive function between controls and cannabis users.

METHODS

A series of three studies explored cognitive function deficits in cannabis users (phonemic verbal fluency, visual recognition and immediate and delayed recall, and prospective memory) in short-term abstinent cannabis users. Participants were selected using snowball sampling, with cannabis users being compared to a standard control group and a tobacco-use control group.

RESULTS

The cannabis users, compared to both control groups, had deficits on verbal fluency, visual recognition, delayed visual recall, and short- and long-interval prospective memory. There were no differences for immediate visual recall.

CONCLUSIONS

These findings suggest that cannabis use leads to impaired executive function. Further research needs to explore the longer term impact of cannabis use.

The dark side of ecstasy: neuropsychiatric symptoms after exposure to 3,4-methylenedioxymethamphetamine

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is a known neurotoxin in animals. This review discusses the history, pattern of use, pharmacology, acute and long-term effects of MDMA. Emphasis is given to the concern that MDMA may induce long-term cognitive and psychiatric effects. MDMA is an illegal substance, and investigations of the effects of exposure in human beings have limitations and weaknesses. There are numerous studies suggesting a correlation between MDMA exposure and psychopathology, and that the psychotropic effects may be long-lasting or permanent. However, it is not possible to conclude that there is a causal relationship between exposure and the increased psychopathology observed in MDMA users. Longitudinal studies are needed to assess whether MDMA causes persistent cognitive impairment and/or psychiatric symptoms in human beings.

Prospective memory impairment in "ecstasy" (MDMA) users

RATIONALE

Considerable research indicates that "ecstasy" users perceive their memory for future intentions (prospective memory) to be impaired. However, only one empirical study to date has directly tested how this capacity is affected by ecstasy use, and this study provided relatively limited information regarding the extent, scope, or implications of problems experienced.

OBJECTIVES

The present study assessed prospective performance on a laboratory measure of prospective memory that closely represents the types of prospective memory tasks that actually occur in everyday life and provides an opportunity to investigate the different sorts of prospective memory failures that occur ("Virtual Week").

METHOD

Ecstasy user group (27 current users and 34 nonusers) was between participants, and prospective memory task (regular, irregular, time-check) was within participants. A measure sensitive to specific aspects of psychopathology was also administered.

RESULTS

Ecstasy users were significantly impaired on Virtual Week, and these deficits were of a comparable magnitude irrespective of the specific prospective memory task demands. The pattern of results was unchanged after controlling for marijuana use, level of psychopathology, and sleep quality. Further, prospective memory was shown to be significantly impaired for both relatively infrequent and relatively frequent ecstasy users, although for the latter group the magnitude of this deficit was greater.

CONCLUSIONS

Prospective memory performance is sensitive to regular and even moderate ecstasy use. Importantly, ecstasy users experience generalized difficulties with prospective memory, suggesting that these deficits are likely to have important implications for day-to-day functioning.

Everyday memory deficits in ecstasy-polydrug users

Recent research suggests that not only does the use of recreational drugs impact on working memory functioning, but more ;everyday' aspects of memory (e.g. remembering to do something in the future) are also affected. Forty-three ecstasy-polydrug users and 51 non-ecstasy users were recruited from a university population. Each participant completed the Cognitive Failures Questionnaire (CFQ) and Everyday Memory Questionnaire (EMQ). Of these, 28 ecstasy-polydrug users and 35 non-ecstasy users completed the Prospective Memory Questionnaire (PMQ). In addition, an objective measure of cognitive failures (the CFQ-for-others) was completed by friends of participants. With the exception of the CFQ-for-others, in each regression equation, cannabis emerged as the only significant predictor of everyday and prospective memory deficits. Significant correlations were found between the different indicators of everyday memory and various measures of illicit drug use. Cannabis featured prominently in this respect. The present study provides further support for cannabis related deficits in aspects of everyday memory functioning. Ecstasy may aLso be associated with cognitive slips, but not to the same extent as cannabis.

Ecstasy (MDMA) and memory function: a meta-analytic update

A meta-analysis was conducted to examine the impact of recreational ecstasy use on short-term memory (STM), long-term memory (LTM), verbal and visual memory. We located 26 studies containing memory data for ecstasy and non-ecstasy users from which effect sizes could be derived. The analyses provided measures of STM and LTM in 610 and 439 ecstasy users and revealed moderate-to-large effect sizes (Cohen's d) of d = -0.63 and d = -0.87, respectively. The difference between STM versus LTM was non-significant. The effect size for verbal memory was large (d = -1.00) and significantly larger than the small effect size for visual memory (d = -0.27). Indeed, our analyses indicate that visual memory may be affected more by concurrent cannabis use. Finally, we found that the total lifetime number of ecstasy tablets consumed did not significantly predict memory performance.

Cannabis and Ecstasy/MDMA (3,4-methylenedioxymethamphetamine): an analysis of their neuropsychobiological interactions in recreational users

The majority of recreational Ecstasy/MDMA users (90-98%) also take cannabis. This co-drug usage is often viewed as a methodological confound, which needs to be removed statistically. Here we take a rather different approach, and debate the potential complexities of their psychobiological interactions. The ring-substituted amphetamine derivate MDMA (3,4-methylendioxymethamphetmaine, or 'Ecstasy') is a powerful CNS stimulant, whereas cannabis is a relaxant. Their co-usage may reflect opposing effects in three psychobiological areas: arousal, body temperature, and oxidative stress. Firstly MDMA is alerting whereas cannabis is sedating. Secondly MDMA is hyperthermic whereas cannabis is hypothermic. Thirdly MDMA increases oxidative stress whereas cannabinoids are antioxidant. Hence cannabis may modulate the acute and sub-acute reactions to MDMA, reduce the acute hyperthermia induced by MDMA, and ameliorate the oxidative stress caused by MDMA. The limited empirical evidence on each topic will be critically examined. In terms of chronic effects each drug is functionally damaging, so that polydrug users generally display cumulative neurobiological impairments. However in certain aspects their neuropsychobiological effects may interactive rather than additive. In particular, the combined use of cannabis and MDMA may have rather different neuropsychobiological implications, than their separate usage. In order to investigate these potential complexities, future research will need better empirical data on the exact patterns of co-drug usage.

Issues of representation in eHealth research (with a focus on web surveys)

The growth of eHealth research has been both rapid and sustained over the past several years. As part of this growth, the Internet is increasingly being used, both to deliver online interventions, and to collect data from a wide variety of groups of people. This paper reviews some of the issues around the latter use of the Internet, and in particular, the use of web surveys to produce results intended to be generalizable to a broader population. The paper provides an overview of issues of sample representation and the challenges faced in using Internet surveys. Various methods of sample selection, and their strengths and weaknesses are reviewed, and the threats to valid inference are discussed.

Acute dose of MDMA (75 mg) impairs spatial memory for location but leaves contextual processing of visuospatial information unaffected

RATIONALE

Research concerning spatial memory in 3,4-methylenedioxymethamphetamine (MDMA) users has presented conflicting results showing either the presence or absence of spatial memory deficits. Two factors may have confounded results in abstinent users: memory task characteristics and polydrug use.

OBJECTIVES

The present study aims to assess whether a single dose of MDMA affects spatial memory performance during intoxication and withdrawal phase and whether spatial memory performance after MDMA is task dependent.

MATERIALS AND METHODS

Eighteen recreational MDMA users participated in a double-blind, placebo-controlled, three-way crossover design. They were treated with placebo, MDMA 75 mg, and methylphenidate 20 mg. Memory tests were conducted between 1.5 and 2 h (intoxication phase) and between 25.5 and 26 h (withdrawal phase) post-dosing. Two spatial memory tasks of varying complexity were used that required either storage of stimulus location alone (spatial memory task) or memory for location as well as processing of content or contextual information (change blindness task).

RESULTS

After a single dose of MDMA, the subjects made larger localization errors and responded faster compared to placebo in the simple spatial memory task during intoxication phase. Inaccuracy was not due to increased response speed, as determined by regression analysis. Performance in the change blindness task was not affected by MDMA. Methylphenidate did not affect performance on any of the tasks.

CONCLUSION

It is concluded that a single dose of MDMA impairs spatial memory for location but leaves processing of contextual information intact.

High-dose MDMA does not result in long-term changes in impulsivity in the rat

RATIONALE

Evidence suggests that recreational users of (+/-)3,4-methylenedioxymethamphetamine HCl (MDMA, "ecstasy") have cognitive and behavioral deficits and show increased impulsivity consistent with 5-hydroxytryptamine (5-HT) neurotoxicity. MDMA effects on impulsivity in users are difficult to establish being confounded by polydrug use and individual predisposition to impulsivity or behavioral inhibition.

OBJECTIVE

We previously observed a long-term anxiolytic effect of a neurotoxic dose of MDMA on elevated plus maze behavior in Dark Agouti (DA) rats while other strains were reported to show anxiogenesis. We have now examined whether MDMA influences impulsivity producing disinhibited behavior interpretable as anxiolysis.

METHODS

Impulsivity was measured using an operant visuospatial discrimination procedure. Male DA rats (n = 24) were trained to lever press for food reward in response to a light-stimulus and subsequently required to withhold responding. Correct responses, premature responses, and response latencies were used as measures of accuracy and impulsivity. Trained rats were administered MDMA (5 mg/kg, i.p. at 3-h intervals to a total of three injections). Performance was measured at 3 h and 7, 27, 49, and 80 days posttreatment.

RESULTS

There was a short-term effect of MDMA on the percentage of correct responses at 3 h and day 1 with recovery to control levels by days 7-8 and no significant long-term changes up to day 80. There was no effect of MDMA on premature responses on any of the days measured. MDMA reduced cortical 5-HT content (MDMA 363 +/- 14 ng/g and control 440 +/- 10 ng/g tissue).

CONCLUSION

These results suggest that impulsivity may not be directly altered by MDMA despite serotonergic neurotoxicity.

Differential experiences of the psychobiological sequelae of ecstasy use: quantitative and qualitative data from an internet study

Previous work provided preliminary evidence that different patterns of use among ecstasy users may impact on perceived side-effects. Participants recruited via an ecstasy-related bulletin board differed in their responses compared to those recruited via other means. The present investigation compares self-reports of psychobiological difficulties among ecstasy users recruited either via a bulletin board or by alternative methods. Qualitative data included reports of any negative or positive changes attributable to ecstasy use and reasons for cessation of use. An Internet-based design was utilized and 209 volunteers completed the study, 117 of whom were recruited via a bulletin board devoted to discussion of ecstasy. Psychobiological difficulties attributable to ecstasy use varied, with mood fluctuation the most common. Differences between the two groups in the extent to which these problems were reported was found. Bulletin board recruits were less likely to report anxiety or poor concentration, but more likely to report tremors/twitches. For the whole sample, lifetime use was associated more with psychobiologial problems, although this pattern was stronger and more pervasive for the non-bulletin board participants. Bulletin board recruits were more aware of possible negative psychological effects and were more likely to report adopting harm reduction strategies. From the qualitative data three negative consequences of use were identified, the most common of which was "psychological problems". In support of the quantitative findings the likelihood of reporting psychological problems increased with lifetime exposure to ecstasy in both recruitment conditions but interestingly this did not appear to impact on reasons for cessation of use. Participants also reported a number of effects that they regarded as beneficial. Future research should also take these aspects of use into account.

Users' perceptions of the risks and effects of taking ecstasy (MDMA): a questionnaire study

This self-report questionnaire study examined ecstasy users' perceptions of the risks associated with their use of ecstasy, their precautions against such risks, and its perceived effects on their lives. Gender differences in these areas were also explored. The sample comprised 328 ecstasy users (139 female, 187 male, one transsexual) with a mean age of 22.5 years (SD = 4.9 years). Questionnaires were completed either in hard copy or through a website concerned with ecstasy use. The results showed that friends were the most common source of information about ecstasy for the sample overall, although females were more likely to utilize this source than males. None of the five categories of perceived risk (e.g. psychiatric, physical) showed a significant gender difference. Males were more likely to take rest breaks whilst females were more likely to limit consumption as a precaution against harm. Three factors emerged from a principal components analysis concerning perceived personal change since initiation of ecstasy use. Factor 1 (23.8% of the variance) concerned negative experiences (e.g. depression). Factor 2 (22.0% of the variance) concerned positive personal qualities (e.g. caring). Factor 3 (10.5% of the variance) concerned selective aspects of functioning (e.g. alertness). The pattern of Factor 1 and Factor 2 scores over time suggested that 6 years since initiation of ecstasy use might be a time when some long-term users may be open to reassess their use of the drug. Broader implications of the findings for health education initiatives aimed at ecstasy users are discussed.

The confounding problem of polydrug use in recreational ecstasy/MDMA users: a brief overview

The popular dance drug ecstasy (3,4-methylenedioxymethamphetamine -- MDMA) is neurotoxic upon central serotonergic neurons in laboratory animals and possibly also in humans. In recent years, several studies reported alterations of serotonergic transmission and neuropsychiatric abnormalities in ecstasy users which might be related to MDMA-induced neurotoxic brain damage. To date, the most consistent findings associate subtle cognitive, particularly memory, deficits with heavy ecstasy use. However, most studies have important inherent methodological problems. One of the most serious confounds is the widespread pattern of polydrug use which makes it dif.cult to relate the findings in user populations to one specific drug. The present paper represents a brief overview on this issue. The most commonly co-used substances are alcohol, cannabis and stimulants (amphetamines and cocaine). Stimulants are also neurotoxic upon both serotonergic and dopaminergic neurons. Hence, they may act synergistically with MDMA and enhance its long-term adverse effects. The interactions between MDMA and cannabis use may be more complex: cannabis use is a well-recognized risk factor for neuropsychiatric disorders and it was shown to contribute to psychological problems and cognitive failures in ecstasy users. However, at the cellular level, cannabinoids have neuroprotective actions and they were shown to (partially) block MDMA-induced neurotoxicity in laboratory animals. In future, longitudinal and prospective research designs should hopefully lead to a better understanding of the relation between drug use and subclinical psychological symptoms or neurocognitive failures and, also, of questions around interactions between the various substances of abuse.

Cannabis use, cognitive performance and mood in a sample of workers

There are well documented acute and chronic effects of cannabis use on mental functioning. However, less is known about any effects on cognition within the context of work and everyday life. The aim of the study was to examine any association between cannabis use and cognitive performance, mood and human error at work. Cannabis users and controls completed a battery of laboratory based computer tasks measuring mood and cognitive function pre- and post-work at the start and end of a working week. They also completed daily diaries reporting their work performance. Cannabis use was associated with impairment in both cognitive function and mood, though cannabis users reported no more workplace errors than controls. Cannabis use was associated with lower alertness and slower response organization. In addition, users experienced working memory problems at the start, and psychomotor slowing and poorer episodic recall at the end of the working week. This pattern of results suggests two possible effects. First a 'hangover'-type effect which may increase with frequency of use. Second a subtle effect on cognitive function, perhaps more apparent under cognitive load and/or fatigue, which may increase with more prolonged use. The results also highlight the importance of the timing of testing within the context and routine of everyday life.

Pattern of cannabis use in ecstasy polydrug users: moderate cannabis use may compensate for self-rated aggression and somatic symptoms

Cannabis is one of the most common 'co-drugs' for ecstasy users. The aim of the present study was to explore self-reported psychobiological problems in ecstasy polydrug users in relation to their pattern of cannabis use. Two hundred and eighty ecstasy polydrug users were allocated into five cannabis groups according to the frequency of their cannabis use. The control group comprised 121 alcohol-tobacco users. There were no significant group differences with regard to age, diagnosed family psychiatric history and level of self-rated stress experienced during 6 months prior to the study. The present study produced three main findings: (a) Ecstasy users with no concomitant use of cannabis displayed more self-rated aggression and somatic symptoms compared with ecstasy users who were smoking cannabis on a monthly or weekly basis. (b) Ecstasy users who reported heavy cannabis use in the past displayed higher paranoid symptoms compared with ecstasy weekly and daily cannabis users. (c) Former heavy cannabis users were the most likely to complain of a variety of ecstasy related long-term problems. In conclusion, moderate cannabis use may help to ameliorate or mask MDMA-induced aggressivity and somatic symptoms. However, this study confirms that heavy cannabis and ecstasy use is associated with several psychobiological problems, which may emerge after a period of abstinence from both drugs.

MDMA (3,4-Methylenedioxymethamphetamine) or ecstasy: the neuropsychobiological implications of taking it at dances and raves

MDMA (3,4-methylenedioxymethamphetamine) or 'ecstasy' is a ring-substituted amphetamine derivative, which is widely used as a recreational drug, most particularly at dances and raves. Around 80-95% of dancers/ravers report using ecstasy/MDMA, compared to 5-15% of young people in general. This paper will consider the possible contribution of stimulatory environmental conditions to the neuropsychobiological effects of MDMA. Animal research shows that heat and crowding potentiate the acute effects of MDMA. Social interaction and intravenous drug self-administration in laboratory rats are significantly enhanced when MDMA is given under hot ambient temperatures. Loud noise and physical activity can also contribute to the general overarousal. Furthermore, MDMA impairs homeostatic thermal control in rats, leading them to overheat in hot environments. The human implications of these findings are that the hot, noisy and overcrowded conditions at raves may be providing the ideal environment to heighten the acute drug response. In recreational users, the acute medical dangers of MDMA comprise a constellation of hyperthermia-related abreactions, which generally only occur when it has been taken in hot and crowded environments. MDMA is well established as a serotonergic neurotoxin in laboratory animals, but heat and overcrowding increase the degree of distal axon terminal loss. If this also occurs in humans, then the stimulatory environments of clubs and raves may heighten the likelihood of adverse neuropsychological sequelae in recreational ecstasy users. Consistent with this prediction, the extent of self-reported dancing/exercise when on MDMA has recently been shown to be associated with significantly more psychobiological problems afterwards.

Nonequivalence of on-line and paper-and-pencil psychological tests: The case of the prospective memory questionnaire

There is growing evidence that Internet-mediated psychological tests can have satisfactory psychometric properties and can measure the same constructs as traditional versions. However, equivalence cannot be taken for granted. The prospective memory questionnaire (PMQ; Hannon, Adams, Harrington, Fries-Dias, & Gibson, 1995) was used in an on-line study exploring links between drug use and memory (Rodgers et al., 2003). The PMQ has four factor-analytically derived subscales. In a large (N = 763) sample tested via the Internet, only two factors could be recovered; the other two subscales were essentially meaningless. This demonstration of nonequivalence underlines the importance of on-line test validation. Without examination of its psychometric properties, one cannot be sure that a test administered via the Internet actually measures the intended construct.