Depression is highly prevalent in the general population and is associated with poor work performance, poor parenting quality, and interpersonal problems. Depression can thus have consequences for society as well as for those directly affected and their children.
Life satisfaction is also considered an important aspect of mental health. Life satisfaction is associated with several positive outcomes such as longevity and good physical health. The present project has therefore focused on both depressive symptoms and life satisfaction when examining mental health.
Social relationships are often seen as one of the most important aspects of human life and are closely related to mental health. Almost all psychological disorders are associated with interpersonal problems, and life satisfaction is associated with good social relationships. Although mental health is affected by both biological factors and different environmental factors at micro and macro levels, the interpersonal perspective on mental health assumes that interpersonal stress can prolong and increase mental health problems regardless of their initial causes. Further, interpersonal stress is seen as a consequence as well as a cause of mental health problems.
Romantic relationships are closely intertwined with mental health, but we have only limited knowledge about the mechanisms involved in the longitudinal associations between relationship quality and mental health.
Population based longitudinal studies are needed to learn more about the associations between relationship quality and mental health over time. However, attrition rates from longitudinal studies are often high, and knowledge is therefore needed about how attrition affects the results from long-term longitudinal studies.
The main aim of the current project was to examine the associations between relationship quality and both depressive symptoms and life satisfaction among men and women. The project also aimed to examine how attrition affects the representativeness of samples in long-term longitudinal studies.
Data from a 15-year population based family study (the TOPP study) with information from both partners were used.
The findings showed that the longitudinal association between relationship satisfaction and depressive symptoms was bidirectional and equally strong in both directions. In addition, relationship quality was associated with life satisfaction over as much as 15 years. This long-term association between relationship quality and life satisfaction was only present among those who stayed together over the 15-year study period. There were no gender differences in any of the findings.
Examination of attrition from the study indicated that those who stayed in the study over the 15-year period did not differ from those who dropped out regarding psychological and relational variables even though those who dropped out had lower educational level than those who stayed. Further, associations between variables at baseline were the same among those who stayed in the study and those who later dropped out. These findings thus indicated that the sample did not become increasingly biased over the 15-year study period regarding psychological and relationship variables or regarding associations between variables.
The findings from the current project suggest that promotion of relationship quality should be a part of public health interventions. The results further suggest that findings on associations between relationship quality and mental health from long-term longitudinal studies can be equally generalizable as results from cross-sectional studies. This emphasizes the importance of long-term longitudinal studies because such studies can provide unique contributions to the understanding of stability and change in mental health and relationship quality.