Content area
Full Text
Psychopharmacology (2015) 232:15711582 DOI 10.1007/s00213-014-3795-8
ORIGINAL INVESTIGATION
fNIRS suggests increased effort during executive access in ecstasy polydrug users
C. A. Roberts & C. Montgomery
Received: 9 June 2014 /Accepted: 22 October 2014 /Published online: 14 November 2014 # Springer-Verlag Berlin Heidelberg 2014
AbstractBackground Ecstasy use is associated with cognitive impairment, believed to result from damage to 5-HT axons. Neuro-imaging techniques to investigate executive dysfunction in ecstasy users provide a more sensitive measure of cognitive impairment than behavioural indicators. The present study assessed executive access to semantic memory in ecstasy polydrug users and non-users.
Methods Twenty ecstasy polydrug users and 20 non-user controls completed an oral variant of the Chicago Word Fluency Test (CWFT), whilst the haemodynamic response to the task was measured using functional near-infrared spectroscopy (fNIRS).
Results There were no between-group differences in many background measures including measures of sleep and mood state (anxiety, arousal, hedonic tone). No behavioural differences were observed on the CWFT. However, there were significant differences in oxy-Hb level change at several voxels relating to the left dorsolateral prefrontal cortex (DLPFC) and right medial prefrontal cortex (PFC) during the CWFT, indicating increased cognitive effort in ecstasy users relative to controls. Regression analyses showed that frequency of ecstasy use, total lifetime dose and amount used in the last 30 days was significant predictors of oxy-Hb increase at several voxels after controlling for alcohol and cannabis use indices.
Conclusion The results suggest that ecstasy users show increased activation in the PFC as a compensatory mechanism, to achieve equivalent performance to non-users. These findings are in agreement with much of the literature in the area
which suggests that ecstasy may be a selective serotonin neurotoxin in humans.
Keywords Cognition . Ecstasy . Cortical oxygenation
Introduction
Ecstasy (MDMA/3,4-methylenedioxymethamphetamine) remains a popular recreational drug, with 3.3 % of 1624-year olds in the UK reporting use in the last year (Crime Survey of England and Wales 2013). Its popularity is of concern given the negative psychological and physiological consequences associated with continued use, which may have real-world functional significance.
The increase in the monoamines serotonin, dopamine and norepinephrine after administration is the primary cause of its acute psychological and physiological effects (McDowell and Kleber 1994). After regular use, down-regulation of serotonin receptors may be seen in...