Cognitive and neuropsychological profiles of recreational ecstasy polydrug users.

The aim of the current thesis was to investigate the neurocognitive functions of regular Ecstasy polydrug use in
drug-free participants, using an integrated methodological approach. Study 1 included two groups of 20 heavy Ecstasy polydrug users; one that had complained of Ecstasy-related problems, the other had described no problems. The controls comprised 20 polydrug users who had never taken Ecstasy. All participants were compared on a range of cognitive tasks. Strategic working memory impairments in both groups of Ecstasy users were found to be as a function of dosage rather than self-reported awareness of problems. In study 2, the same Ecstasy groups were administered a series of structured questions regarding their drug use behaviour and life changes both prior to and following the use of Ecstasy. In contrast to the cognitive data, usage was less related to dose, and more to poor pre-morbid adjustment. In Study 3, a group of 20 Ecstasy polydrug users were
compared with 20 polydrug controls on selected tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Ecstasy users demonstrated impaired short-term memory and showed trends towards impairment on several learning paradigms, whereas most measures associated with prefrontal functioning were unimpaired. Study 4 compared 22 Ecstasy polydrug users with 22 polydrug controls on prepulse inhibition (PPI). The blink reflex component of startle was analysed by recording electromyographic (EMG) responses to auditory stimuli. No group differences in response magnitude of PPI were established in either 60 or 70 dB prepulse conditions. Study 5 compared four groups of 14 participants: Long-term Ecstasy users (10 years or
more), short-term Ecstasy users (up to 5 years), polydrug controls and a drug naive group. All groups were
compared on selected tasks from the CANTAB, however, due to sampling problems only the data from the two Ecstasy groups was analysed. The long-term users showed increased memory impairment and selective executive deficits compared with short-term users. In conclusion, Ecstasy polydrug use results in selective shortterm memory and executive deficits. These impinge on certain learning processes, but appear to be relatively independent of robust attentional measures. In relation to executive functioning, moderate Ecstasy polydrug users showed few impairments on measures of strategic control and no deficits on measures of inhibitory functioning. They did, however, reveal visual, verbal and spatial short-term memory deficits. Compared with
moderate users, heavy Ecstasy users demonstrated increased short-term memory deficits and increased strategic impairment on planning tasks. Broad anatomical interpretations suggest that moderate Ecstasy polydrug users
showed a predominantly posterior and temporal/limbic profile of impairment, with a relative sparing of executive function. However, tentative difficulties regarding reversal learning, attentional learning and verbal fluency, suggest some specific problems associated with frontal circuitry. These deficits became more apparent in heavy and or long-term users.

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