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

Everyday memory deficits in ecstasy-polydrug users

Rationale/Objectives: Recent research suggests that not only does the use of recreational drugs impact working memory functioning, but more “everyday” aspects of memory (e.g. remembering to do something in the future) are also affected. Methods: 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. Results: There was a main effect of ecstasy-polydrug use on CFQ, EMQ, CFQ-for-others, Long-Term (LT) PM and internally cued PM scores. These were slightly attenuated following control for working memory capacity. Correlations were found between the different indicators of everyday memory and various measures of illicit drug use. Cannabis featured prominently in this respect. In addition, all ecstasy-related deficits were reduced to below statistical significance following control for cannabis use. Conclusions: 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

Sleep Impairment in Ecstasy/Polydrug and Cannabis-Only Users

The present study investigated aspects of sleep quality in ecstasy and cannabis users. Two-hundred and twenty seven participants (117 ecstasy/polydrug users, 53 cannabis users and 57 drug naive participants) took part. The participants completed measures of daytime sleepiness, and indicators of sleep quality. The results demonstrated that ecstasy/polydrug users viewed themselves as being more evening types and having poorer sleep quality than cannabis users and drug naive participants. They were also more likely to have missed a night's sleep. The reported differences in sleep type may reflect ecstasy-related serotonergic dysfunction resulting in problems with shifting circadian rhythms

The nature of ecstasy-group related deficits in associative learning

Rationale/objectives: Research has revealed associative learning deficits among users of ecstasy; the present study explored the component processes underlying these deficits. Methods: Thirty-five ecstasy users and 62 non-ecstasy users completed a computer-based, verbal paired-associates learning task. Participants attempted to learn eight sequentially presented word pairs. After all eight had been presented, the first member of each pair was displayed and participants attempted to recall the second. Eight trials were administered. Correct responses on each trial, forgetting at various levels of learning, perseveration errors and the rate at which the associations were learned (trials to completion) were all recorded. Results: MANOVA revealed that ecstasy users performed worse overall and subsequent ANOVAs showed that users performed significantly worse on virtually all measures. Regression analysis revealed that over half of the ecstasy-group related variance in trials to completion was attributable to group differences in initial learning and forgetting. In relation to forgetting, it appears that cannabis use may be an important determinant. In relation to rate of learning (trials to completion) and initial learning, both ecstasy and cannabis may be implicated. Conclusions: There appears to be abundant evidence of associative learning deficits among ecstasy users. However, it appears that a range of illicit drugs including cannabis and ecstasy may contribute to these deficits

Differences in prefrontal blood oxygenation during an acute multitasking stressor in ecstasy polydrug users

Background: Cognitive deficits are well documented in ecstasy (MDMA) users with such deficits being taken as evidence of dysregulation of the 5HT system. More recently neuroimaging has been used to corroborate these deficits. The present study aimed to assess multitasking performance in ecstasy polydrug users, polydrug users and drug naïve individuals. It was predicted that ecstasy polydrug users would perform worse than nonusers on the behavioural measure and this would be supported by difference in cortical blood oxygenation. Methods: Twenty ecstasy-polydrug users, 17 polydrug users and 19 drug naïve individuals took part. On day 1 drug use history was taken and questionnaire measures were completed. On day 2, participants completed a 20 minute multitasking stressor while brain blood oxygenation was measured using functional near infrared spectroscopy (fNIRS). Results: There were no significant differences between the 3 groups on the subscales of the multitasking stressor. In addition, there were no significant differences on self-report measures of perceived workload (NASA – TLX). In terms of mood, ecstasy users were significantly less calm and less relaxed compared to drug-naïve controls. There were also significant differences at 3 voxels on the fNIRS indicating decreased blood oxygenation in ecstasy users compared to drug naïve controls at V2 (left DLPFC), V14 and V16 (right DLPFC), and compared to polydrug controls at V14. Conclusions: The results of the present study provide support for changes in brain activation during performance of demanding tasks in ecstasy polydrug users, which could be related to cerebral vasoconstriction

Electrophysiological Evidence of Atypical Processing Underlying Mental Set Shifting in Ecstasy Polydrug and Polydrug Users

Executive functioning deficits are reported in ecstasy users. However research into mental set switching has been equivocal, with behavioural studies suggesting the function is preserved. The current study sought to address the issue of switching deficits in ecstasy users by combining behavioural performance with electrophysiological correlates (EEG). Twenty ecstasy polydrug users, 20 non-ecstasy polydrug users and 20 drug naive controls were recruited. Participants completed questionnaires about their drug use, sleep quality, fluid intelligence and current mood state. Each participant completed a mental set switching task (the number-letter task) whilst EEG measures were recorded. ANOVA revealed no between group differences on performance of the task, however a regression suggested that ecstasy use was a significant predictor for performance, after controlling for cannabis use. Mixed ANOVA revealed a significant effect of group on the P3, with significant differences between both drug groups and naives. There was also an interaction between electrode and group on the P2 component, with ecstasy users differing from both other groups. On the P3 component the results suggest a reduction in positivity at parieto-occipital electrodes for drug users compared to controls. Furthermore a significant increase in negativity in ecstasy users compared to control groups could be observed in several occipito-parietal electrodes at an N2 component as well as observable atypicalities in early processing (P2) displayed by ecstasy users and polydrug controls. The present study provides evidence of atypical processing of attentional shifting in ecstasy and polydrug users. Deficits in this executive function could reflect cognitive inflexibility and paucity of rapid behavioural adjustment, which may be problematic in real world situations. Keywords: Ecstasy; cannabis; executive function; stimulants; cannabis

Effects of ecstasy/polydrug use on memory for associative information

Rationale. Associative learning underpins behaviours that are fundamental to the everyday functioning of the individual. Evidence pointing to learning deficits in recreational drug users merits further examination. Objectives. A word pair learning task was administered to examine associative learning processes in ecstasy/polydrug users. Methods. After assignment to either single or divided attention conditions, 44 ecstasy/polydrug users, and 48 nonusers were presented with 80 word pairs at encoding. Following this, four types of stimuli were presented at the recognition phase; the words as originally paired (old pairs), previously presented words in different pairings (conjunction pairs), old words paired with new words, and pairs of new words (not presented previously). The task was to identify which of the stimuli were intact old pairs. Results. Ecstasy/ploydrug users produced significantly more false positive responses overall compared to nonusers. Increased long-term frequency of ecstasy use was positively associated with the propensity to produce false positive responses. It was also associated with a more liberal signal detection theory (SDT) decision criterion value. Measures of long term and recent cannabis use were also associated with these same word pair learning outcome measures. Conjunction word pairs, irrespective of drug use, generated the highest level of false positive responses and significantly more false positive responses were made in the DA condition compared to the SA condition. Conclusions. Overall, the results suggest that long-term ecstasy exposure may induce a deficit in associative learning and this may be in part a consequence of users adopting a more liberal decision criterion value. Key Words: Ecstasy, Drug Use, Cognition, Memory, Associative Learning, Word Pair

Investigating the central executive in adult dyslexics: Evidence from phonological and visuospatial working memory performance

There is long-standing evidence for verbal working memory impairments in both children and adults with dyslexia. By contrast, spatial memory appears largely to be unimpaired. In an attempt to distinguish between phonological and central executive accounts of the impairments in working memory, a set of phonological and spatial working memory tasks was designed to investigate the key issues in working memory, task type, task demands (static, dynamic, and updating), and task complexity. Significant differences emerged between the dyslexic and nondyslexic participants on the verbal working memory tasks employed in Experiment 1, thereby providing further evidence for continuing dyslexic impairments of working memory into adulthood. The nature of the deficits suggested a problem with the phonological loop, with there being little evidence to implicate an impairment of the central executive. Due to the difficulties associated with separating verbal working memory and phonological processing, however, performance was investigated in Experiment 2 using visuospatial measures of working memory. The results of the visuospatial tasks indicated no between-group differences in static spatial memory, which requires the short-term storage of simultaneously presented information. In almost all conditions there were no between-group differences in dynamic spatial memory that demands the recall of both locationand order of stimuli presented sequentially. However, a significant impairment occurred on the dynamic task under high memory updating load, on which dyslexic adults showed nonphonological working memory deficits. In the absence of an explanation involving verbal recoding, this finding is interpreted in terms of a central executive or automaticity impairment in dyslexia

Dyslexic students have more everyday cognitive lapses.

There is a dearth of information about the everyday performance difficulties of adult dyslexic people. This study investigates the empirical support for anecdotal reports of increased vulnerability to distraction in dyslexia, using the self-report Cognitive Failures Questionnaire (CFQ). Two groups of university students, a dyslexic group and a non-dyslexic control group, were asked to complete the CFQ. The dyslexic group reported a higher frequency of everyday lapses in cognition, scoring significantly higher on a number of CFQ items. Representative problems include distractibility, over-focusing (so that relevant peripheral information is missed), and word-finding difficulties. A similar measure administered to close friends of dyslexic people, the CFQ-for-others, yielded results consistent with those of the CFQ, with major findings being that their friends considered them to be more disorganised, more distractible, and more absent-minded than normal. The results indicate clearly the continuing effects of dyslexia on cognition in adulthood and demonstrate that dyslexic impairments are not limited to "artificial" laboratory tasks or even literacy tasks but, instead, pervade everyday life

Effects of ecstasy/polydrug use on memory for associative information

Rationale Associative learning underpins behaviours that are fundamental to the everyday functioning of the individual. Evidence pointing to learning deficits in recreational drug users merits further examination. Objectives A word pair learning task was administered to examine associative learning processes in ecstasy/polydrug users. Methods After assignment to either single or divided attention conditions, 44 ecstasy/polydrug users and 48 non-users were presented with 80 word pairs at encoding. Following this, four types of stimuli were presented at the recognition phase: the words as originally paired (old pairs), previously presented words in different pairings (conjunction pairs), old words paired with new words, and pairs of new words (not presented previously). The task was to identify which of the stimuli were intact old pairs. Results Ecstasy/ploydrug users produced significantly more false-positive responses overall compared to non-users. Increased long-term frequency of ecstasy use was positively associated with the propensity to produce false-positive responses. It was also associated with a more liberal signal detection theory decision criterion value. Measures of long term and recent cannabis use were also associated with these same word pair learning outcome measures. Conjunction word pairs, irrespective of drug use, generated the highest level of false-positive responses and significantly more false-positive responses were made in the divided attention condition compared to the single attention condition. Conclusions Overall, the results suggest that long-term ecstasy exposure may induce a deficit in associative learning and this may be in part a consequence of users adopting a more liberal decision criterion value