The association between well-being and the COMT gene: Dispositional gratitude and forgiveness as mediators

Highlights

• We found that individuals with the smaller number of the Met alleles reported greater well-being, less depressive symptoms, and greater tendencies for gratitude and forgiveness.

• We found that dispositional gratitude and forgiveness mediated the genotype effects on well-being and depressive symptoms.

• This study demonstrates the contribution of the COMT gene to well-being, dispositional gratitude, and dispositional forgiveness, highlights the importance of gratitude and forgiveness in the relationship between the gene and well-being, and suggests a psychobiological pathway for well-being and depression.

Abstract

Backround

Previous studies have demonstrated the contributions of genetic variants and positive psychological traits (e.g. gratitude and forgiveness) to well-being. However, little is known about how genes interact with positive traits to affect well-being.

Methods

To investigate to what extent the COMT Val158Met polymorphism modulates well-being and to what extent dispositional gratitude and forgiveness mediate the individual differences in well-being, 445 participants were recruited and required to complete a battery of questionnaires.

Results

We found that individuals with a smaller number of the Met alleles reported greater well-being, less depressive symptoms, and greater tendencies for gratitude and forgiveness. Moreover, dispositional gratitude and forgiveness mediated the genotype effects on well-being and depressive symptoms. These results remained significant after controlling for non-genetic factors (socioeconomic status, religious beliefs, romantic relationship status, parenting style).

Limitation

The sample size limits the generalizability of results.

Conclusion

This study demonstrates the contribution of the COMT Val158Met polymorphism to individual differences in well-being and suggests a potential psychobiological pathway from dopaminergic and noradrenergic systems to happiness.

Introduction

Well-being (also termed “happiness”) refers to the positive cognitive and affective evaluations of the evaluator’s life (Diener et al., 1999) as well as the evaluator’s experience of self-realization and good social relationships (Ryan and Deci, 2001). Well-being is beneficial to multiple life domains including physical and mental health and work performance (Lyubomirsky et al., 2005). The pursuit of well-being is one of the unalienable rights of human beings, as stated in the Declaration of Independence of the United States. However, the Declaration of Independence only guarantees the right to pursue well-being, not well-being per se.

The experience of well-being is strikingly variable between individuals. Twin studies have established that a large portion of individual differences in well-being can be attributed to genetic factors, with heritability estimates of 38–54% (Lykken and Tellegen, 1996, Røysamb et al., 2002, Stubbe et al., 2005). Genetic studies also showed the involvement of serotoninergic genes in well-being (Chen et al., 2013, De Neve, 2011). Moreover, a recent large-scale genome-wide association study identified a set of genetic variants associated with well-being and depressive symptoms (Okbay et al., 2016). However, the existing evidence is insufficient for us to understand the psychobiological basis of well-being. The purpose of the current study is to investigate to what extent a particular polymorphism on the catechol-O-methyltransferase (COMT) gene would modulate well-being and to what extent individual differences in well-being are mediated by personality traits such as dispositional gratitude and forgiveness.

The COMT gene is located on chromosome 22q11 (Grossman et al., 1992). It encodes COMT protein, one of the major enzymes to degrade catecholamines such as dopamine and norepinephrine. Within the gene, a transition of guanine (G) to adenine (A) at codon 158, namely COMT Val158Met (rs4680), leads to a mutation of valine (Val) to methionine (Met). The Val/Val genotype is associated with about a 40% increased enzyme activity in the brain compared to the Met/Met genotype (Chen et al., 2004, Lachman et al., 1996).

Previous studies have demonstrated the role of the COMT Val158Met in response to positive and negative emotional stimuli (Bouhuys et al., 1999, Cohn et al., 2009), a fundamental process involved in well-being (Diener et al., 2009a, Diener et al., 1999, Gross and John, 2003). A handful of studies reported that the Met allele was associated with increased sensitivity to pleasant stimuli (Wichers et al., 2008) and decreased sensitivity to unpleasant stimuli (Amstadter et al., 2012). Other studies, however, did not find a link between the COMT gene and the experience of positive affects (Bakker et al., 2014, Desmeules et al., 2012, Wacker et al., 2012) or anticipation of positive affects (Katz et al., 2015). Indeed, more studies showed an opposite pattern with increased negativity bias in affective processing for the Met allele (Gao et al., 2016, Kia-Keating et al., 2007, Ohara et al., 1998, Smolka et al., 2005, Williams et al., 2010). For example, clinical research demonstrated that the susceptibilities to depression and suicidal behavior were increased in the Met allele carriers (Kia-Keating et al., 2007, Ohara et al., 1998); neuroimaging studies also showed that the Met allele was associated with increased neural responses to negative emotional stimuli (Smolka et al., 2005) and decreased neural responses to positive facial expressions (Williams et al., 2010).

As far as we know, there is no study directly investigating the effect of the COMT Val158Met polymorphism on well-being, which is related to, but much more complex than, say, affective processing. Moreover, although a few previous studies demonstrated the involvement of serotoninergic genes in well-being (Chen et al., 2013, De Neve, 2011), these studies asked participants to evaluate their satisfaction with lives in no more than 4 items and, more seriously, did not reveal what factors might mediate the association between gene and well-being. Psychological studies have found that well-being can be mostly accounted for by positive personality traits, particularly dispositional gratitude and forgiveness (Bono et al., 2008, Emmons and McCullough, 2003). Dispositional gratitude predicts subjective well-being ratings (Wood et al., 2008a) and gratitude training promotes well-being (Emmons and McCullough, 2003). Similarly, increases in forgiveness predict increases in well-being (Bono et al., 2008) and forgiveness intervention improves well-being (Zhang et al., 2014). Taking into account the causal links of gratitude and forgiveness to well-being (Bono et al., 2008, Emmons and McCullough, 2003; Wood et al., 2008a; Zhang et al., 2014) and the general knowledge that genetic factors affect behavioral phenotypes through psychological traits (Davis and Loxton, 2013, Saphire-Bernstein et al., 2011), we hypothesized that COMT Val158Met may affect well-being through dispositional gratitude and forgiveness.