title: In for a penny, in for a pound: methylphenidate reduces the inhibitory effect of high stakes on persistent risky choice.
abstract: Methylphenidate (MPH) is a stimulant that increases extracellular levels of dopamine and noradrenaline. It can diminish risky decision-making tendencies in certain clinical populations. MPH is also used, without license, by healthy adults, but the impact on their decision-making is not well established. Previous work has found that dopamine receptor activity of healthy adults can modulate the influence of stake magnitude on decisions to persistently gamble after incurring a loss. In this study, we tested for modulation of this effect by MPH in 40 healthy human adults. In a double-blind experiment, 20 subjects received 20 mg of MPH, while 20 matched controls received a placebo. All were provided with 30 rounds of opportunities to accept an incurred loss from their assets or opt for a "double-or-nothing" gamble that would either avoid or double it. Rounds began with a variable loss that would double with every failed gamble until it was accepted, recovered, or reached a specified maximum. Probability of recovery on any gamble was low and ambiguous. Subjects receiving placebo gambled less as the magnitude of the stake was raised and as the magnitude of accumulated loss escalated over the course of the task. In contrast, subjects treated with MPH gambled at a consistent rate, well above chance, across all stakes and trials. Trait reward responsiveness also reduced the impact of high stakes. The findings suggest that elevated catecholamine activity by MPH can disrupt inhibitory influences on persistent risky choice in healthy adults.
authors.affiliation: Centre of Functionally Integrative Neuroscience, Aarhus University, 8000 Aarhus, Denmark. dan.cfin@gmail.com
authors.forename: Daniel
authors.initials: D
authors.lastname: Campbell-Meiklejohn
authors.forename: Arndis
authors.initials: A
authors.lastname: Simonsen
authors.forename: Jørgen
authors.initials: J
authors.lastname: Scheel-Krüger
authors.forename: Victoria
authors.initials: V
authors.lastname: Wohlert
authors.forename: Trine
authors.initials: T
authors.lastname: Gjerløff
authors.forename: Chris D
authors.initials: CD
authors.lastname: Frith
authors.forename: Robert D
authors.initials: RD
authors.lastname: Rogers
authors.forename: Andreas
authors.initials: A
authors.lastname: Roepstorff
authors.forename: Arne
authors.initials: A
authors.lastname: Møller
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003657:Decision Making / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D005717:Games, Experimental; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology*; D009042:Motivation / Q000187:drug effects; D010551:Personality / Q000187:drug effects; D011336:Probability; D011930:Reaction Time / Q000187:drug effects; D012201:Reward; D012309:Risk-Taking; D013647:Task Performance and Analysis; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate