Residual neurocognitive features of long‐term ecstasy users with minimal exposure to other drugs

Abstract

Aims In field studies assessing cognitive function in illicit ecstasy users, there are several frequent confounding factors that might plausibly bias the findings toward an overestimate of ecstasy-induced neurocognitive toxicity. We designed an investigation seeking to minimize these possible sources of bias. Design We compared illicit ecstasy users and non-users while 1) excluding individuals with significant lifetime exposure to other illicit drugs or alcohol; 2) requiring that all participants be members of the “rave” subculture; and 3) testing all participants with breath, urine, and hair samples at the time of evaluation to exclude possible surreptitious substance use. We compared groups with adjustment for age, gender, race/ethnicity, family-of-origin variables, and childhood history of conduct disorder and attention deficit hyperactivity disorder. We provide significance levels without correction for multiple comparisons. Setting Field study. Participants Fifty-two illicit ecstasy users and 59 non-users, age 18-45. Measurements Battery of 15 neuropsychological tests tapping a range of cognitive functions. Findings We found little evidence of decreased cognitive performance in ecstasy users, save for poorer strategic-self-regulation, possibly reflecting increased impulsivity. However this finding might have reflected a premorbid attribute of ecstasy users, rather than a residual neurotoxic effect of the drug. Conclusions In a study designed to minimize limitations found in many prior investigations, we failed to demonstrate marked residual cognitive effects in ecstasy users. This finding contrasts with many previous findings—including our own—and emphasizes the need for continued caution in interpreting field studies of cognitive function in illicit ecstasy users.

Electrophysiological evidence of atypical processing underlying mental set shifting in ecstasy polydrug and polydrug users.

“…Few previous studies have found cognitive atypicalities (Halpern et al, 2004), however those who have previously suggested no deficit in this executive function have neither had the purity of the cohort examined in the Halpern et al, (2004) study, nor perhaps equivalent lifetime dose. However in the follow up study (Halpern et al, 2011) using participants with minimal exposure to other drugs and a larger sample size, the effects of MDMA on switching were not evident, so perhaps of greater importance, is the use of more sensitive measures of cognitive impairment such as EEG.…”

“…However in a follow up study (Halpern et al, 2011) with a larger sample and similar controls for concomitant drug use and other lifestyle variables, no such behavioural deficits in relation to switching were observed. However Dafters et al (2006) did observe deficits in ecstasy users over cannabis users and controls, in a task switching version of the Stroop task.…”

‘Ecstasy Use, by Itself, Does Not Result in Residual Neurotoxicity’– A Powerful Argument?

“…We read with interest the paper published in this journal by Halpern and colleagues [1], which reported findings from a study examining cognitive function in ecstasy/ 3,4-methylenedioxymethamphetamine (MDMA) users. The authors conclude that they had failed to demonstrate 'marked residual cognitive effects in ecstasy users' and they suggest that their data may indicate that ecstasy use, by itself, does not result in 'residual neurotoxicity'.…”

Mechanisms of Action and Persistent Neuroplasticity by Drugs of Abuse

“…However, many studies do not properly match MDMA users and controls in terms of education, intelligence quotient, and other variables. When subjects are properly matched, no consistent detrimental effects of MDMA are observed (Halpern et al, 2011).…”