The influence of dopaminergic gene variants on decision making in the ultimatum game

Abstract

One of the most prominent paradigms in neuroeconomics is the ultimatum game (UG) that provides a framework for the study of pro-social behavior in two players interacting anonymously with each other: Player 1 has to split an endowment with player 2. Player 2 can either accept or reject the offer from player 1. If player 2 accepts the offer then the money is split as proposed by player 1. In case of rejection both players get nothing. Until now only one twin study investigated the heritability of the behavior in the UG. Results indicated a strong heritability for the decision behavior of player 2 whereas no genetic influence on player 1 behavior could be detected. Further studies are mandatory to validate these heritability estimates. However, a first candidate polymorphism, the DRD4 exon III, constituting the biological basis of the heritability in the responder behavior has already been identified in a Chinese sample (Zhong et al., 2010). Until now genetic studies in Caucasians on the UG are lacking. The present study wants to fill this gap by investigating the UG in a healthy German sample. Moreover, we intend to find candidate genes that are associated with the first-mover-behavior. In a sample of N = 130 healthy participants an online version of the UG was conducted and polymorphisms of the dopamine D2 receptor gene (DRD2) and the DRD4 exon III VNTR were genotyped. We could confirm the DRD4 exon III effect on the responder behavior and the absence of an effect on the proposer behavior reported before. In line with Zhong et al. (2010) carriers of the 4/4 genotype showed a significant higher minimal acceptable offer (p = 0.023) than subjects with any other genotype. Furthermore, a DRD2-haplotype-block containing the single nucleotide polymorphisms rs1800497 and rs2283265 was significantly associated with the amount player1 offered (p = 0.005) but not with the decision of player 2. Results support the importance of the dopaminergic system for pro-social behavior.

Impact of nutrition on social decision making

“…Genetic studies indicate a link between the dopamine system and social punishment (20), suggesting a dosedependent dopamine effect. Furthermore, fMRI studies have suggested a role for mesolimbic dopamine in social decisions (21).…”

Dopamine D4 receptor gene and religious affiliation correlate with dictator game altruism in males and not females: evidence for gender-sensitive gene × culture interaction

“…In both studies the absence of the exon III 7R was associated with altruism measured with self-report questionnaires. DRD4 has also been related to reciprocal fairness measured with Ultimatum Game (Zhong et al, 2010 ) in Han Chinese participants, subjects homozygous for the 4R stated a 25% higher minimal acceptable offer indicating higher demand for fairness; similar finding has been reported later on among an independent Caucasian sample, where the 4/4R genotype carriers stated a 20% higher minimal acceptable offer than carriers without 4/4R genotype (mainly 7R carriers; Reuter et al, 2013 ). However, other studies suggest that the effect of DRD4 on prosociality is contingent on environment (see Jiang et al, 2013 for a review).…”

Identifying new susceptibility genes on dopaminergic and serotonergic pathways for the framing effect in decision-making

“…Twin studies yield a moderate heritability of the susceptibility to framing in decision-making ( Simonson and Sela, 2011 ; Cesarini et al , 2012 ; Cronqvist and Siegel, 2012 ). Other studies also demonstrated important roles of genetic variations on dopaminergic and serotonergic pathways in decision-making under risks ( Crişan et al , 2009 ; Dreber et al , 2009 ; Kuhnen and Chiao, 2009 ; He et al , 2010 ; Frydman et al , 2011 ; Heitland et al , 2012 ; Reuter et al , 2013 ; Set et al , 2014 ). By extending the few studies on the genetic basis of the framing effect ( Crişan et al , 2009 ; Roiser et al , 2009 ; Gao et al , 2016 ) and by using a gene-based PCReg approach, we investigated directly the relationship between 26 genes within the dopaminergic and the serotonergic pathways and individuals’ susceptibility to framing in decision-making.…”

“…The susceptibility to framing in decision-making, which varies substantially across individuals ( Kahneman and Tversky, 1979 ; Sharp and Salter, 1997 ; De Martino et al , 2006 ; Roiser et al , 2009 ; Gao et al , 2016 ), has moderate heritability ( Simonson and Sela, 2011 ; Cesarini et al , 2012 ; Cronqvist and Siegel, 2012 ), suggesting that genetic variations contribute to the individual differences. Although genetic studies on risk-taking have demonstrated the important role of genetic variations on dopaminergic and serotonergic pathways in decision-making under risks ( Crişan et al , 2009 ; Dreber et al , 2009 ; Kuhnen and Chiao, 2009 ; He et al , 2010 ; Frydman et al , 2011 ; Heitland et al , 2012 ; Reuter et al , 2013 ; Set et al , 2014 ), only a few studies investigated directly the genetic basis of the susceptibility to framing in decision-making. Two studies ( Crişan et al , 2009 , N = 36; Roiser et al , 2009 , N = 30) showed the association between 5-HTTLPR variable number of tandem repeats variation, the genetic variation in the promoter region of the serotonin transporter gene ( SLC6A4 ), and individuals’ susceptibility to framing.…”