Genetic link found to emotional sensitivity in stressful situations

In a recent study published in Scientific Reports, researchers assess how genetic variation in a cluster of differentiation 38 (CD38) is associated with increased personal distress in an emotionally evocative situation. 

Study: CD38 genetic variation is associated with increased personal distress to an emotional stimulus. Image Credit: Dragana Gordic / Shutterstock.com

CD38 and oxytocin

Oxytocin is a peptide neurohormone that is actively involved in social behavior, including parent-infant bonding, particularly in the immediate period following childbirth, romantic relationships, and group dynamics. Oxytocin-related genetic variants have been associated with various effects on empathy, brain activation during emotion recognition tasks, responses to trauma, and the risk of autism.

Recently, researchers have identified that A allele carriers of the CD38 single nucleotide polymorphism (SNP) rs3796863 had higher plasma oxytocin levels, a more sensitive approach to parenting, and stronger empathic responses. However, other studies have reported that students with the AA genotype of the CD38 SNP reported higher levels of suicide ideation, depressive symptoms, and greater alienation from parents and peers.

These conflicting findings have led some researchers to theorize that A carriers may be more socially sensitive, which, as a result, could lead to a stronger negative emotional response during stressful situations. Despite this concept, no study to date has assessed the impact of the CD38 genotype on negative reactivity to an emotionally stressful situation.

About the study

For the present study, researchers recruited Canadian university students 18 years of age and older with no health issues expected to influence hormone levels. All study participants were shown a three-minute video depicting a father narrating the story of his child’s terminal cancer.

After the video, study participants completed a questionnaire seeking to assess their emotional response to 12 emotions, six of which involved feelings of empathic concern, whereas the remaining six included feelings of personal distress. These responses were rated on a scale from one to five, with higher scores indicating higher endorsement of the emotional response. 

Two Interpersonal Reactivity Index (IRI) subscales, including the personal distress and empathic concern subscales, were used to explore whether the CD38 genotype related to dispositional measures of emotional responses. Participants completed the IRI approximately 10 minutes after watching the emotional video, during which they rated their responses on a five-point Likert scale, with a higher score indicating increased empathy.

Study findings

A total of 171 students participated in the current study, 24, 77, and 70 of whom had the AA, AC, and CC genotypes of the CD38 SNP, respectively. 

The average distress-related response ratings were higher for females than males and AA/AC than CC genotypes, thus suggesting that sex and CD38 genotype affected these responses but not their interaction. Females also scored higher than males on empathy-related responses; however, these scores were not significantly different among the different genotypes.

On both IRI subscales, sex had a significant effect, with females scoring higher than males. However, the IRI subscale results were not significantly different between the CD38 genotypes.

When seeing someone in distress, people with the A allele reported insignificant levels of empathy, a well-recognized response of care, but markedly higher levels of personal distress, a self-focused emotional reaction. 

An empathy-inducing situation may elicit these two responses simultaneously; however, they can have different consequences. For example, while empathy promotes helping behavior to relieve the distress of the individual in need, a person in distress may have the urge to alleviate their own distress rather than offer help to the other person in need of help.

Conclusions

The current study provides preliminary evidence that genetic variation in CD38 influences social-emotional sensitivity. To this end, A allele carriers were more vulnerable to distress-related emotions in response to a negative social stressor. 

The study findings may reconcile paradoxical findings that CD38 A allele carriers are more empathetic despite exhibiting worse interpersonal outcomes. Despite having greater empathy, their high levels of personal distress may prevent appropriate social support from being provided when involved in social conflict. 

This data on oxytocin-related genetic variants could be used to predict individuals for whom the buffer against stress and anxiety in response to challenging interpersonal situations is weaker. Given their inability to regulate their negative emotions, these individuals should receive adequate and timely support.

Future studies, especially in interpersonal contexts, need to use more natural empathy paradigms to assess the role of CD38 in emotional regulation.