Cortical oxygenation suggests increased effort during cognitive inhibition in ecstasy polydrug users.
BACKGROUND
It is understood that 3,4-methylenedioxymethamphetamine (ecstasy) causes serotonin dysfunction and deficits in executive functioning. When investigating executive function, functional neuroimaging allows the physiological changes underlying these deficits to be investigated. The present study investigated behavioural and brain indices of inhibition in ecstasy-polydrug users.


METHODS
Twenty ecstasy-polydrug users and 20 drug-naïve participants completed an inhibitory control task (Random Letter Generation (RLG)) while prefrontal haemodynamic response was assessed using functional near infrared spectroscopy (fNIRS).


RESULTS
There were no group differences on background measures including sleep quality and mood state. There were also no behavioural differences between the two groups. However, ecstasy-polydrug users displayed significant increases in oxygenated haemoglobin (oxy-Hb) from baseline compared to controls at several voxels relating to areas of the inferior right medial prefrontal cortex, as well the right and left dorsolateral prefrontal cortex. Regression analysis revealed that recency of ecstasy use was a significant predictor of oxy-Hb increase at two voxels over the right hemisphere after controlling for alcohol and cannabis use indices.


CONCLUSIONS
Ecstasy-polydrug users show increased neuronal activation in the prefrontal cortex compared to non-users. This is taken to be compensatory activation/recruitment of additional resources to attain similar performance levels on the task, which may be reversible with prolonged abstinence.
Department of Psychological Sciences, Institute of Psychology, Health and Society, University of Liverpool, UK.
C A
CA
Roberts
School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK c.a.montgomery@ljmu.ac.uk.
Catharine
C
Montgomery
D000328:Adult; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000503:physiopathology*; D055030:Drug Users / Q000523:psychology*; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D013287:Illicit Drugs / Q000009:adverse effects; D007266:Inhibition, Psychological; D008297:Male; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000009:adverse effects*; D009483:Neuropsychological Tests; D010100:Oxygen / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism*; D013055:Spectrophotometry, Infrared; D055815:Young Adult
D013287:Illicit Drugs; D018817:N-Methyl-3,4-methylenedioxyamphetamine; D010100:Oxygen
Cognition; drugs; ecstasy; fNIRS; memory