In the study, researchers asked married couples to complete questionnaires about their relationships and collected saliva and blood samples to test participants' levels of a key stress-related hormone and numbers of certain immune cells.
The research focused on attachment anxiety. Those who are on the high end of the attachment anxiety spectrum are excessively concerned about being rejected, have a tendency to constantly seek reassurance that they are loved, and are more likely to interpret ambiguous events in a relationship as negative.
Married partners who were more anxiously attached produced higher levels of cortisol, a steroid hormone that is released in response to stress, and had fewer T cells - important components of the immune system's defense against infection - than did participants who were less anxiously attached.
"Everyone has these types of concerns now and again in their relationships, but a high level of attachment anxiety refers to people who have these worries fairly constantly in most of their relationships," Lisa Jaremka, lead author of the study and a postdoctoral fellow in Ohio State University's Institute for Behavioral Medicine Research (IBMR) said.
Though some scientists theorize that attachment anxiety can be traced to inconsistent care during one's infancy, Jaremka noted that there is also research-based evidence that people with attachment anxiety can change.
The study is set to be published in the journal Psychological Science.