Association between OPRM1 polymorphisms and personality in a Japanese population

Abstract

Objective: Mu-opioid receptor gene OPRM1 118A>G polymorphisms have been considered possible candidate factors for both opioid effects and psychophysical responses. In this study, we investigate the association between OPRM1 118A>G polymorphisms and personality traits. Method: After written informed consent was obtained from participants, OPRM1 118A>G gene polymorphisms were analyzed by polymerase chain reaction (PCR)—restriction fragment length polymorphism (RFLP), and personality was assessed using Neuroticism Extraversion Openness-Five Factor Inventory (NEO-FFI) and State-Trait Anxiety Inventory (STAI) in 236 Japanese university students. Statistical analyses were performed by the unpaired t-test and Welch’s t-test. Results: A significant relationship was found between OPRM1 118A>G polymorphisms and NEO-FFI and STAI scores: participants with the A allele exhibited a higher conscientiousness score (p = 0.024) and a lower neuroticism score (p = 0.065) in NEO-FFI, and a lower STAI score (p = 0.023) than those without the A allele. Conclusion: We conclude that OPRM1 may affect conscientiousness and neuroticism measured using NEO-FFI and trait anxiety measured using STAI.