The research, published in the July issue of the journal Health Psychology was based on participants' survey responses, which the study authors used to determine their types of relationships. 

"Participants were surveyed about their relationships to determine if they had secure attachments (being comfortable depending on others and being close to others), avoidant attachments (feeling uncomfortable being close to others and having difficulty trusting others) or anxious attachments (feeling reluctant about getting close to people and worrying about not being loved)."

Study subjects were also asked to provide information about their medical histories and ongoing chronic conditions such as heart disease or diabetes. Controlling for factors such as depression, anxiety or other disorders, the researchers found that participants whose relationships were characterized as avoidant were more likely to suffer from pain conditions such as chronic headaches compared with those in secure relationships. Those who were insecure in their relationships were more likely to suffer from a range of health problems including heart disease, and faced a 50% higher risk for heart attack or stroke compared with those not plagued by relationship anxiety.

Acadia psychologist Lachlan McWilliams suggests that the findings could have broader implications for understanding the underlying factors that contribute to some chronic conditions, as well as ways to reduce risk. 

“These findings suggest that insecure attachment may be a risk factor for a wide range of health problems, particularly cardiovascular diseases... The findings also raise the possibility that interventions aimed at improving attachment security could also have positive health outcomes.”

 

Source: http://wellness.blogs.time.com/2010/07/20/relationship-anxiety-may-cause-more-than-heartache/