Certain traits in romantic partners can amplify the impact of a person’s genetic risk for alcohol problems microbiologystudy

A study led by Virginia Commonwealth University and Rutgers University has revealed new insights into how romantic partners can influence a person’s genetic predisposition to unhealthy alcohol use. The research team specifically found that the substance use habits, personality traits and mental health status of long-term partners can enhance or diminish the impact of a person’s genetic risk for binge drinking. The findings could help reshape strategies for couples therapy and couple-based alcohol interventions.

“This research sheds new light on the complicated and unforeseen ways that spouses and long-term partners can shape our health and well-being,” said Mallory Stephenson, Ph.D., a postdoctoral fellow at the Virginia Institute for Psychiatric and Behavioral Genetics within the VCU School of Medicine.

Stephenson co-led the research with Jessica E. Salvatore, Ph.D., previously of VCU and now an associate professor of psychiatry at the Rutgers Robert Wood Johnson Medical School. The findings were published in Clinical Psychological Science.

A person’s genes account for approximately 50% of their risk for alcohol use disorder and other forms of risky drinking, but the influence of these genetic factors can change depending on a person’s environment.

“For example, if a person has a high genetic risk for alcohol use disorder and experiences a traumatic event, such as the death of a close relative or exposure to a natural disaster, their biology could play more of a role in whether or not they develop an alcohol problem in response to that stressor,” Stephenson said.

“However, if that person isn’t experiencing anything stressful in their life, their genetic risk may not have as much influence on their drinking behavior.”

Previous VCU-led research revealed that people with a genetic predisposition to risky alcohol behavior are less likely to drink frequently, become intoxicated often or suffer from alcohol dependence symptoms if they are in a romantic relationship. In this new study, the researchers sought to better understand whether any particular characteristics exhibited by a romantic partner can impact a person’s genetic risk for drinking.

To answer this question, Stephenson and her colleagues examined anonymized data from FinnTwin16, a longitudinal study of twins identified from Finland’s Central Population Registry. They specifically looked at Finnish twins in their 30s who were in long-term relationships and had a history of alcohol use.

The researchers analyzed survey responses from 1,620 twins and their romantic partners, including responses on their drinking and smoking habits, personality characteristics and mental health status.

“Twin studies are a really useful tool to disentangle the genetic and environmental influences on our lives,” Stephenson said.

“By studying fraternal twins, which share 50% their genetic makeup, and identical twins, which share 100% of their genetic makeup, we can gain insights into how genetic and environmental factors interact with each other and play a role in developing certain behaviors.”

One of the researchers’ findings was consistent with previous studies: that a person in early midlife was more likely to consume alcohol and engage in binge drinking if their romantic partner also frequently drank alcohol or smoked cigarettes. (When specifically looking at identical twin pairs, the researchers found that romantic partners had a greater influence on the drinking behavior of male twins compared with female twins.)

But through statistical modeling, the researchers also found evidence of more interplay. They saw that that genetic risk for binge drinking had a greater effect in people whose romantic partners smoked cigarettes more frequently, were less conscientious, were more extroverted or reported higher neuroticism or psychological distress.

On the other hand, the heritability of binge drinking had less of an effect on people whose partners reported more frequent alcohol use, a finding that was surprising to the research team.

“We didn’t expect to see this result; however, we think this could mean that the drinking behavior of romantic partners could have a larger effect on a person’s environmental influences rather than their genetic influences,” Stephenson said.

“You can think of these environmental and genetic influences like a pie chart. If the impact of one of these factors makes up a smaller piece of the pie, then the impact of another factor makes up a larger piece.”

The research underscores the important but complex ways in which romantic partners affect a person’s health. From a clinical perspective, the researchers say these findings could inform strategies for couples therapy and couple-based alcohol interventions, which are typically designed to focus on relationship dynamics rather than personal characteristics.

“Even if you have a good relationship with your partner, this research shows that their substance use, personality traits and mental health can still have an impact on you,” Stephenson said.

The researchers say more work is needed to better understand the various ways romantic partners influence drinking outcomes. They are currently looking into how relationship characteristics and the role of parenthood may come together to shape a person’s drinking habits.