Abnormal frontal activations related to decision-making in current and former amphetamine and opiate dependent individuals.
BACKGROUND
There is converging evidence for impairments in decision-making in chronic substance users. In the light of findings that substance abuse is associated with disruptions of the functioning of the striato-thalamo-orbitofrontal circuits, it has been suggested that decision-making impairments are linked to frontal lobe dysfunction. We sought to investigate this possibility using functional neuroimaging.


METHODS
Decision-making was investigated using the Cambridge Risk Task during H2(15)O PET scans. A specific feature of the Risk Task is the decisional conflict between an unlikely high reward option and a likely low reward option. Four groups, each consisting of 15 participants, were compared: chronic amphetamine users, chronic opiate users, ex-drug users who had been long-term amphetamine/opiate users but are abstinent from all drugs of abuse for at least 1 year and healthy matched controls without a drug-taking history.


RESULTS
During decision-making, control participants showed relatively greater activation in the right dorsolateral prefrontal cortex, whereas participants engaged in current or previous drug use showed relatively greater activation in the left orbitofrontal cortex.


CONCLUSIONS
Our results indicate a disturbance in the mediation by the prefrontal cortex of a risky decision-making task associated with amphetamine and opiate abuse. Moreover, this disturbance was observed in a group of former drug users who had been abstinent for at least 1 year.
Ersche
K D
KD
Department of Psychiatry, School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK. ke220@cam.ac.uk
Fletcher
P C
PC
Lewis
S J G
SJ
Clark
L
L
Stocks-Gee
G
G
London
M
M
Deakin
J B
JB
Robbins
T W
TW
Sahakian
B J
BJ
D000328:Adult; D017668:Age of Onset; D019969:Amphetamine-Related Disorders / Q000473:pathology / Q000503:physiopathology*; D000704:Analysis of Variance; D001931:Brain Mapping; D003657:Decision Making / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D009293:Opioid-Related Disorders / Q000473:pathology / Q000503:physiopathology*; D049268:Positron-Emission Tomography / Q000379:methods; D017397:Prefrontal Cortex / Q000473:pathology / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D013997:Time Factors