Nikola Jane Bridges

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

RationaleProspective 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.ObjectivesExtending 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.ResultsEcstasy/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.ConclusionsPM 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.

The effects of acute, chronic and withdrawn progesterone in male and female Mongolian gerbils (Meriones unguiculatus) in two tests of anxiety

Progesterone generally produces anxiolytic effects in rats and mice. However, sex differences in response to this neuroactive steroid have not been systematically investigated. Thus, this study investigated the anxiety-modulating actions of acute, chronic and withdrawn progesterone treatment in male and female Mongolian gerbils (Meriones unguiculatus) in the elevated plus-maze (EPM) and black-white box (BWB). Gerbils were tested after receiving vehicle, 0.5, 2.5, 7.5 or 15 mg/kg progesterone administered acutely, chronically (14 days) or after a 24-h withdrawal period following chronic treatment. Data analyses showed that overall the effects of progesterone were similar in males and females. Progesterone produced few behavioural alterations in the EPM following any of the treatment regimes. However, acute and chronic progesterone reduced anxiety in the BWB (as shown by increased exploration, locomotion and entries into the white compartment). In contrast, withdrawal of progesterone produced minimal effects in the EPM and BWB. This study suggests that the BWB maybe the most suitable test for detecting the anxiolytic effects of neuroactive steroids in gerbils. However, further research is needed to clarify the behavioural effects of progesterone in this species.

Anxiolytic and anxiogenic drug effects on male and female gerbils in the black-white box

Neurokinin-1, (NK1) receptor antagonists offer strong potential as anxiolytic drugs with few side effects. The use of the Mongolian gerbil for anxiety research offers advantages because gerbil NK1 receptors share a greater homology with human NK1 receptors than those of other rodents. Studies are needed to validate existing tests of anxiety for use with this species. This study examined the effects of two anxiolytics (buspirone and diazepam) and two anxiogenics (caffeine and FG142) on male and female gerbil behaviour in the black-white box (BWB). Diazepam was anxiolytic in males but not females. The anxiolytic effects of buspirone were apparent at the lower doses in both males and females. Higher doses resulted in sedative effects in both sexes. Caffeine produced mild anxiogenesis in females at the lowest dose, and in males at the highest dose. FG7142 was mildly anxiogenic in males and not at all in females. Findings are discussed in light of previous research. The gerbil BWB should not be used as a valid test of anxiety in its current form.

Self-reports of Executive Dysfunction in Current Ecstasy/Polydrug Users

Objectives/Background:Ecstasy/polydrug users have exhibited deficits in executive functioning in laboratory tests. We sought to extend these findings by investigating the extent to which ecstasy/polydrug users manifest executive deficits in everyday life. Methods:Forty-two current ecstasy/polydrug users, 18 previous (abstinent for at least 6 months) ecstasy/polydrug users, and 50 non-users of ecstasy (including both non-users of any illicit drug and some cannabis-only users) completed the self-report Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) measure. Results:Current ecstasy/polydrug users performed significantly worse than previous users and non-users on subscales measuring inhibition, self-monitoring, initiating action, working memory, planning, monitoring ongoing task performance, and organizational ability. Previous ecstasy/polydrug users did not differ significantly from non-users. In regression analyses, although the current frequency of ecstasy use accounted for statistically significant unique variance on 3 of the 9 BRIEF-A subscales, daily cigarette consumption was the main predictor in 6 of the subscales. Conclusions:Current ecstasy/polydrug users report more executive dysfunction than do previous users and non-users. This finding appears to relate to some aspect of ongoing ecstasy use and seems largely unrelated to the use of other illicit drugs. An unexpected finding was the association of current nicotine consumption with executive dysfunction.

The Role of Executive Processes in Accounting for Prospective Memory Deficits in Ecstasy/Polydrug Users

In order to investigate the role of executive processes in accounting for prospective memory deficits in ecstasy/polydrug users a sample of seventy three ecstasy/polydrug users and sixty seven polydrug/non-ecstasy users (control group) were assessed on executive functions and prospective memory measures. The self-report measure of executive function, the BRIEF-A was used to capture any possible behavioral manifestations of executive function in ecstasy/polydrug users in comparison to the control group. Three laboratory measures of prospective memory assessing short-term and long-term time based prospective memory and event based prospective memory were developed and administered. The short-term time based prospective memory task required the participants to ask for a questionnaire (measuring their level of fatigue) every 20 minutes throughout their test session. The percentage of occasions that the participant remembered to ask for the questionnaire was calculated for the first and the second half of the test session as well as the overall percentage. In the long term time based prospective memory test (PM element) participants were asked to post a delayed recall test in a prepaid envelope one, two, and three weeks after the test session. Finally, in the event based prospective memory test participants had to indicate whether two patterns appearing on the computer screen were different or the same, while at the same time remembering to press the F1 key at the end of each test segment in order to record their scores.