title: Sweet future: fluctuating blood glucose levels affect future discounting.
abstract: This study explored metabolic mechanisms of future (delay) discounting, a choice phenomenon where people value present goods over future goods. Using fluctuating blood glucose as an index of body-energy budget, optimal discounting should regulate choice among rewards as a function of temporal caloric requirement. We identified this novel link between blood glucose levels measured in the lab and future-discounting rates of participants, who made choices between a "smaller and sooner" reward and a "larger but later" option, with possible actual monetary rewards. A group of participants who drank a soft drink that contained sugar showed a reduced rate of future discounting afterward, when we controlled for sex, age, body mass index, and the taste of the drink. In contrast, a group of participants who drank a soft drink that contained artificial sweetener showed an increased rate of future discounting. Blood glucose levels not only varied as a result of caloric intake but also regulated the rate of future discounting, according to participants' dynamic body-energy budget.
authors.affiliation: Department of Psychology, University of South Dakota, Vermillion, SD 57069, USA. xtwang@usd.edu
authors.forename: X T
authors.initials: XT
authors.lastname: Wang
authors.forename: Robert D
authors.initials: RD
authors.lastname: Dvorak
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D002755:Choice Behavior / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D003657:Decision Making / Q000502:physiology; D002149:Energy Intake / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D006801:Humans; D033182:Intention; D008297:Male; D008875:Middle Aged; D009042:Motivation; D012201:Reward; D055815:Young Adult
chemical_list: D001786:Blood Glucose