The COMT Val158Met polymorphism exerts a common influence on avoidant attachment and inhibited personality, with a pattern of positive heterosis
Introduction
A strong relationship between adult attachment and personality dimensions has been described, as well as a high heritability of both constructs. Independent studies of twins have estimated that heritability of attachment is around 40% (Fearon et al., 2014), and behavioral genetics research, on its part, has shown that 40–60% of the variability in personality traits is hereditary (Vukasović and Bratko, 2015). A multivariate behavioral genetic analysis conducted with a broad sample of twins (Donnellan et al., 2008) proved in fact that a significant proportion of the association between attachment and personality was attributable to common genetic influences. These findings suggest that individual differences in internal working models of relationships may result from a process of co-construction of personality and attachment styles with a shared genetic contribution. There is abundant literature on the influence of specific polymorphisms on personality traits (Vukasović and Bratko, 2015); research on the contribution of individual polymorphisms to attachment, on the contrary, is limited. Furthermore, to the best of our knowledge, no publication has reported the effect of specific polymorphisms on both constructs hitherto.
Certain genes that participate in dopamine and serotonin pathways, such as catechol-O-methyltransferase and serotonin transporter, stand out among those genes that have been associated to personality traits and attachment patterns. Specifically, the catechol-O-methyl-transferase Val158Met (COMT Val158Met) and the serotonin transporter promoter length (5HTTLPR) polymorphisms have been independently associated to both constructs (Calati et al., 2011, Delvecchio et al., 2016, Luijk et al., 2011, Raby et al., 2012). Based on these findings, in this study we aimed to explore whether they exert a common influence on personality and attachment dimensions in a sample of healthy individuals. Personality and attachment were explored using the Spanish validated versions of The Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ) and Experiences in Close Relationships (ECR) respectively. We first examined the relationship between personality and attachment dimensions. Subsequently, we explored the associations between the personality and attachment dimensions and the selected polymorphisms, and assessed whether the observed genetic associations underlay interrelated dimensions.
Section snippets
Methods
A total of 101 volunteers participated in the study (69 women and 32 men, average age 39.71 ± 6.50 years). The participants were workers from different professional categories, recruited by a trained nurse during a routine visit to the occupational health department of the Mental Health Network of Biscay. They were provided information concerning this study about the influence of genetic polymorphisms on personality and attachment and the procedures of the research, and were invited to
Results
There was a significant relationship between the COMT Val158Met genotypes and the scores of the DAPP-BQ inhibitedness dimension and of the ECR avoidant attachment (Table 1). Additionally, inhibitedness and avoidant attachment were significantly correlated (r = 0.77, p < 0.001). No common associations of other genotypes to related aspects of attachment and personality were found. Homozygotes for the long allele of 5HTTLPR scored significantly higher for inhibitedness. We have not found any
Discussion
In our sample, composed of adults that were assessed using self-reports, the COMT Val158Met polymorphism shows a common association with features of personality and attachment that are interrelated: inhibitedness and avoidant attachment. This finding is consistent with the results from the multivariate behavioral genetic analysis mentioned above (Donnellan et al., 2008) that reported that much of the overlap between adult attachment and personality traits was explained by common genetic
Conflicts of interest
The authors have nothing to disclosure.
Acknowledgement
This work was supported by the Health Department of the Basque Government (Spain) under Grant PI2014111034.
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