Gene by gender interplay in moral choices

While philosophers, psychologists and cognitive scientists have proposed distinct definitions of moral judgment, recent studies suggest that moral choices are modulated by neurobiological mechanisms. The pioneering works by Greene showed that certain brain areas may be considered “specific” for moral decision and provided support for a dual-process theory, according to which two different patterns of neural activity are involved in moral choices: a fast, unconscious "emotional" system, and a slow, conscious "cognitive" system1, 2, 3. Furthermore, genetic associations between two allelic variants in serotonin transporter and oxytocin receptor genes, and moral judgment have been reported4, 5. Because of their described association with impulsive behavior6, 7, 8, 9, we questioned whether four polymorphisms in genes involved in serotonergic and dopaminergic neurotransmission (SLC6A3–VNTR, DRD4-VNTR, DRD4 rs1800955, COMT rs4680) would modulate the cognitive and emotional processes at the basis of controversial moral choices. After signing an informed consent, 200 (102F) University students were recruited in a moral dilemma paradigm (N=56) designed to assess three variables: moral action type (Means vs Side Effect), life expectancy (Normal vs Reduced), self-involvement (Involvement vs Non-Involvement). They also provided saliva samples for DNA collection and completed the Impulsivity-Venturesomeness-Empathy Questionnaire (I7). Significant differences between males and females were observed in the I7 scale scores. Moreover, only in males Venturesomeness scores correlated with the number of utilitarian responses. Males, compared to females, gave a higher number of utilitarian responses, showed longer response times for non-utilitarian answers and judged as more acceptable the endorsed moral actions. Interestingly, only females showed a significant association between allelic variants involved in dopamine level regulation in striatum and prefrontal cortex, and moral choices. Our results are the first ones showing that impulsivity and genetic profile influence moral judgment in a gender-related manner, thus shedding new light on the neurobiological mechanisms underlying moral choices. BIBLIOGRAPHY 1. Greene JD, Sommerville RB, Nystrom LE, Darley JM, Cohen JD (2001). An fMRI investigation of emotional engagement in moral judgment. Science 293(5537): 2105–2108. 2. Greene JD, Nystrom LE, Engell AD, Darley JM, Cohen JD (2004). The neural bases of cognitive conflict and control in moral judgment. Neuron 44(2): 389–400. 3. Greene JD (2009). Dual-process morality and the personal/impersonal distinction: a reply to McGuire, Langdon, Coltheart, and Mackenzie. J Exp Soc Psychol 45(3): 581-584. 4. Marsh AA, Crowe SL, Yu HH, Gorodetsky EK, Goldman D, Blair RJR (2011). Serotonin transporter genotype (5-HTTLPR) predicts utilitarian moral judgments. Plos One 6(10): e25148. 5. Walter NT, Montag C, Markett S, Felten A, Voigt G, Reuter M (2012). Ignorance is no excuse: moral judgments are influenced by a genetic variation on the oxytocin receptor gene. Brain and Cognition 78(3): 268-273. 6. Munafò MR, Yalcin B, Willis-Owen SA, Flint J (2008). Association of the dopamine D4 receptor (DRD4) gene and approach-related personality traits: meta-analysis and new data. Biol Psychiatry 63(2): 197-206. 7. Joyce PR, McHugh PC, Light KJ, Rowe S, Miller AL, Kennedy MA (2009). Relationships between angry-impulsive personality traits and genetic polymorphisms of the dopamine transporter. Biol Psychiatry 66(8): 717-721. 8. Reiner I, Spangler G (2011). Dopamine D4 receptor exon III polymorphism, adverse life events and personality traits in a nonclinical German adult sample. Neuropsychobiology 63(1): 52-58. 9. Soeiro-De-Souza MG, Stanford MS, Bio DS, Machado-Vieira R, Moreno RA (2013). Association of the COMT Met158 allele with trait impulsivity in healthy young adult. Mol Med Rep 7(4): 1067-1072.