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College of Health and Human Sciences
Jessica Huber

Marriage, Mental Health and Well-being: Researcher Connects the dots

Susan South

Susan South, PhD

Assistant Professor of Psychological Sciences


PhD, University of Virginia, Charlottesville, 2006
Clinical Psychology (APA-Accredited)
Dissertation: Personality Pathology Assessed by Self- and Other Report: Implications for Marital Satisfaction and Conflict

MA, University of Virginia, Charlottesville, 2001
Clinical Psychology
Thesis: Interpersonal Perception and Personality Disorders: Accuracy and Stability of Peer and Self-Report

BA, University of Virginia, Charlottesville, 1999
Distinguished Majors Program (with High Honors)

Susan South, PhD, credits IU Researcher Amy Holtzworth-Munroe for altering the course of her research career. South began graduate school studying personality disorders but soon after narrowed her focus to explore the dynamic relationship between mental illness and the marital relationship. "I was fascinated by Amy's work on adult intimate relationship problems, and I became interested in marital relationships," says South. "I wanted to understand how two completely separate people with distinct personalities and backgrounds mesh in a marriage and how mental illness contributes to marital satisfaction."
It's an ongoing research course she is committed to, evidenced thus far by 36 professional articles in press or published and another 14 published book chapters. One could say she hasn't looked back.

Research Methods

South utilizes two primary types of data to examine several questions related to mental health and physical well-being and the effects on marriage.
One is behavior genetic data from twin studies, including a large sample collected by colleagues from the University of Minnesota, where South did her postdoctoral fellowship from 2006-08. The other is through the collection of information from married couples from the community, including Indiana's Tippecanoe County.

Twin studies enable researchers to quantify the relative influence of nature (i.e., genetics) and nurture (i.e., environment) on outcomes like health and well-being. South notes, "Twins are a great way of testing theoretical models, in this case, of how marital relationships can impact genetic influences on physical and mental health." Results just published in an article co-authored by South titled, "Marital Satisfaction and Physical Health: Evidence for an Orchid Effect," in Psychological Science, indicate evidence of the orchid effect: the idea that genetic influences on physical health are enhanced in non-normative — both unusually positive and unusually negative — environmental contexts. "We found that genetic influences on the variation in self-reported health were greatest at both high and low levels of marital satisfaction, suggesting that both really good marriages and really bad marriages can change how genetic influences on health are expressed," she says.

Also through twin studies, South and her team have determined that when people are genetically predisposed for mental illness, for example, depression or anxiety disorder, stress in the marriage can be a trigger for the illness to manifest. "It is a thorny issue, however," states South. "It's a little like what came first, the chicken or the egg? Individuals come into a marriage with one's own issues. Do the issues cause marital stress? Or does marital stress cause the mental health issues?"

South recently finished community sampling of more than 100 couples. "Over the course of a year, we conducted three waves of samples. Couples gave several hours to answer questions about their relationship, communication issues, personality and mental health issues," she says. "They also kept daily journals, which are very helpful for us to see the day-by-day look at what people are doing and saying to each other."

What's Next?

Future plans include continuing twin studies with the University of Minnesota and later this year collaborating with the Norwegian Institute of Public Health Twin Panel. South also hopes to enhance the process of community surveying by collecting data in Indianapolis, a more diverse urban population.

"My goal is to determine the 'why' with all of this. What is it about personality and mental illness that disrupts a marital relationship?" says South. Continuing to probe this issue, she continues, could have implications with counseling methods that take into greater account individual personality traits and differences and influences on mental illness.

"Nearly 75% percent of people in the U.S. will get married at some point in their lives, and when you add in cohabiting relationships it's clear that almost all of us will be in a long-term intimate relationship," she adds. "The quality of that relationship can affect physical and mental health and overall well-being."