A 12-year longitudinal study examined how couples’ depressive symptoms change over time, revealing four distinct patterns of symptom change. The results were published in the journal Translational psychiatrysuggests that couples’ depressive symptoms either remain consistent together or evolve in the same direction.
Depression is a common mental illness, but symptoms vary from person to person. There is reason to believe that a person’s social relationships can influence the course of their depression, and that the depressive symptoms of one romantic partner can influence another. This line of reasoning is based on interdependence theory, which states that partners’ traits influence each other over time. While most studies have examined individual trajectories of depressive symptoms, study author Zsófia Csajbók and her team instead looked at couples’ trajectories.
“It’s been known for a long time that couples are more alike, but there are many other explanations for this,” explained Chaibok, assistant professor of psychology at Charles University in Prague. “Also, similarities in one period do not tell much about how they change over time in relation to each other. This was especially interesting in the context of significant parallels in mental health, where we can observe over time (people get better, swingers seek help, bad things happen, they get worse, etc.).
The researchers drew on data from a six-wave longitudinal study called the Survey on Health, Aging and Retirement in Europe (SHARE). The study included biannual assessments of depressive symptoms over a 12-year period. Csajbók and colleagues limited their analysis to heterosexual couples who had at least three assessments of depressive symptoms, giving them a sample of 11,136 couples (mean age 60) from 16 European countries.
The study authors used a statistical technique called dyadic growth mixture modeling to examine how couples’ depressive symptoms changed over time. Based on their trajectory, couples are grouped into one of four classes. The largest group included 76.9% of couples and both partners were characterized by stable low depressive symptoms. Then, in 8.1% of couples, female partners consistently had higher depressive symptoms and male partners consistently had lower symptoms. Finally, in 7.2% of couples, both partners experienced a decrease in depressive symptoms, and in 7.8% of couples, both partners experienced an increase in symptoms.
Notably, both groups with increased and decreased symptoms followed the same direction of symptom change—both partners’ symptoms increased or both partners’ symptoms decreased. However, the rate of change in symptoms was not uniform. For example, in the group in which both partners’ symptoms decreased, male partners began with depressive symptoms and then experienced a decrease in symptoms compared to their female partners.
The researchers said their findings did not identify any couples with truly different symptoms — for example, there was no class in which one partner’s symptoms increased over time and the other’s decreased. In addition, a group with persistent depressive symptoms in both partners was not identified. According to the authors, this suggests that people with severe depression do not form relationships together, or if they do, it is unstable and short-lived.
“What we can say with certainty so far is that we’re trying to understand how couples influence each other’s well-being,” Chaibok told PsyPost. “Hopefully this will help provide better treatment because it will focus practitioners on longer-term samples from a larger unit than the patient, couple-level samples. It is not new that the network of family relationships affects people’s well-being and vice versa. But this study could help better identify those at risk.”
As expected, couples in the group in which both partners’ symptoms worsened over time were more likely to report separation or divorce. Compared to couples who were chronically depressed, they had poorer health and poorer health.
Csajbók and colleagues say their findings have implications for both clinical practice and the social sciences. They argue that it is not appropriate to treat all couples equally because couples vary in their trajectories of depressive symptoms. These differences mean that couples likely require different intervention methods.
“Not all couples consistently show the same long-term pattern, and this may be the reason why we have not yet determined which mechanisms are responsible for couple similarity — it may be due to different mechanisms in different cases,” Chaibok said. “We are interested in how these patterns are developed and what mechanisms are responsible for them, but that is open to further research. We believe that the future of this field is to explore the heterogeneity of our samples. When we pool the entire sample in a study, not all results will hold for everyone, and we expect to gain greater precision by examining these contrasts.
Limitations of the study include the sample consisting of western, industrialized, wealthier and more educated societies. Results may not generalize to people of other backgrounds. “We also tested a general older population that was already married — there are limitations to knowing how the relationship started, how long it took for the trajectory we see in the 50s, 60s, and 70s,” Chaibok said. . “We will address these issues in future studies.”
“It’s important to note that these are just observations we’ve made, but we don’t know enough about individual couples to dig deeper into what causes their depression,” he added.
“Changing Trajectories of Depressive Symptoms in a Large Sample of Couples” Zsofia Chaibok, Zuzana Shterbova, Peter K. Written by Jonasson, Pavla Chermakova, Adam Doka and Jan Havlicek.