Being in a Romantic Relationship Is Associated with Reduced Gray Matter Density in Striatum and Increased Subjective Happiness.

Hiroaki Kawamichi,Norihiro Sadato,Masahiro Matsunaga,Yuki H Hamano,Kai Makita,Yuichi Ogino,Hiroki C Tanabe,Shigeru Saito,Sho K Sugawara

doi:10.3389/fpsyg.2016.01763

Abstract

Romantic relationship, a widespread feature of human society, is one of the most influential factors in daily life. Although stimuli related to romantic love or being in a romantic relationship commonly result in enhancement of activation or functional connectivity of the reward system, including the striatum, the structure underlying romantic relationship-related regions remain unclear. Because individual experiences can alter gray matter within the adult human brain, we hypothesized that romantic relationship is associated with structural differences in the striatum related to the positive subjective experience of being in a romantic relationship. Because intimate romantic relationships contribute to perceived subjective happiness, this subjective enhancement of happiness might be accompanied by the experience of positive events related to being in a romantic relationship. To test this hypothesis and elucidate the structure involved, we compared subjective happiness, an indirect measure of the existence of positive experiences caused by being in a romantic relationship, of participants with or without romantic partners (N = 68). Furthermore, we also conducted a voxel-based morphometry study of the effects of being in a romantic relationship (N = 113). Being in a romantic relationship was associated with greater subjective happiness and reduced gray matter density within the right dorsal striatum. These results suggest that being in a romantic relationship enhances perceived subjective happiness via positive experiences. Furthermore, the observed reduction in gray matter density in the right dorsal striatum may reflect an increase in saliency of social reward within a romantic relationship. Thus, being in a romantic relationship is associated with positive experiences and a reduction of gray matter density in the right dorsal striatum, representing a modulation of social reward.

Highlights

Romantic love, which is essentially a human universal, is widespread across cultures throughout the world (Jankowiak and Fischer, 1992) and is presumed to be experienced by the vast majority of people
Voxel-based morphometry results showed that the gray matter density of the right dorsal striatum [top peak = (26, 14, 12)] of the in-relationship group was significantly lower than that of the no-relationship group (Table 1; Figures 1 and 2)
Because we did not find any significant correlation between average beta-value in significant clusters and SHS scores [two groups (68 participants): r(66) = −0.120, p = 0.331; in-relationship group (36 participants): r(34) = −0.114, p = 0.508], the significant difference in gray matter density in the right dorsal striatum could be primarily attributed to being in a romantic relationship

Summary

Introduction

Romantic love, which is essentially a human universal, is widespread across cultures throughout the world (Jankowiak and Fischer, 1992) and is presumed to be experienced by the vast majority of people. Higher levels of commitment in romantic relationships are associated with a tendency to underrate attractive alternatives (Johnson and Rusbult, 1989; Maner et al, 2009); romantic love functions to maintain relationships and diminish the desire to search for alternative mates. In this sense, romantic love is an essential aspect of well-being and positive experience in human society. In this sense, being in a romantic relationship is one of most positive influential experiences of human adulthood

Results

Discussion

Conclusion