Mild opioid deprivation increases the degree that opioid-dependent outpatients discount delayed heroin and money.
BACKGROUND
A growing literature suggests that excessive temporal discounting of delayed rewards may be a contributing factor in the etiology of substance abuse problems. Little is known, however, about how drug deprivation may affect temporal discounting of delayed rewards by drug-dependent individuals.


OBJECTIVE
To examine the extent to which opioid deprivation affects how opioid-dependent individuals discount small, medium and large quantities of delayed heroin and money.


METHODS
Thirteen opioid-dependent individuals maintained on buprenorphine completed a hypothetical choice task in which they choose between a constant delayed reward amount and an immediate reward amount that was adjusted until they expressed indifference between both outcomes. The task was completed for three values of heroin and money rewards during eight sessions under conditions of opioid deprivation (four sessions) and satiation (four sessions).


RESULTS
Across conditions, hyperbolic functions provided a good fit for the discounting data. Degree of discounting was significantly higher when subjects were opioid deprived. Consistent with previous findings, degree of discounting was higher for heroin than money and inversely related to the magnitude of the reward.


CONCLUSIONS
Opioid deprivation increased the degree to which dependent individuals discounted delayed heroin and money. Understanding the conditions that affect how drug-dependent individuals discount delayed rewards might help us understand the myopic choices made by such individuals and help improve treatment outcomes.
Department of Psychiatry, University of Vermont, Burlington, VT 05401, USA. giord003@mc.duke.edu
Louis A
LA
Giordano
Warren K
WK
Bickel
George
G
Loewenstein
Eric A
EA
Jacobs
Lisa
L
Marsch
Gary J
GJ
Badger
D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000704:Analysis of Variance; D005260:Female; D003932:Heroin / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009293:Opioid-Related Disorders / Q000191:economics* / Q000523:psychology*; D010045:Outpatients / Q000523:psychology; D012055:Reinforcement Schedule; D012201:Reward
D000701:Analgesics, Opioid; D003932:Heroin