Plasma interleukin-6 and soluble IL-6 receptors are associated with psychological well-being in aging women

Objective: This study tested the hypothesis that psychological well-being would predict lower plasma levels of inflammatory factors in aging women.

Design: One hundred thirty-five women ages 61-91 years (M = 74.5 years) participated in this study. After completing self-administered questionnaires in their homes, participants stayed overnight at the General Clinical Research Center (GCRC) at the University of Wisconsin-Madison. Blood samples for cytokine analyses were obtained in participants' homes after the GCRC visit.

Main outcome measures: Psychological well-being and ill-being, history of health problems, and health behaviors were assessed via self-administered questionnaires. Detailed medical history and concurrent health measures were obtained during the GCRC stay. Enzyme-linked immunosorbent assays were used to determine interleukin-6 (IL-6) and soluble IL-6 receptor (sIL-6R) concentrations in plasma.

Results and conclusion: Regression analyses showed that plasma IL-6 levels were lower in women scoring higher on positive relationships, whereas sIL-6R levels were lower in women scoring higher on purpose in life, even after a variety of sociodemographic and health factors were controlled. These outcomes, combined with the absence of significant links with other measures of well-being and ill-being, suggest selective patterns of association between later life inflammatory processes and psychological factors, particularly those focused on positive ties with others and purposeful engagement.