The cytokine interleukin-6 (IL-6) has become a focus of research into age-related inflammatory diseases. IL-6 regulation is known to be subject to psychological influences, and elevated levels of it are associated with increases in stress and depression. This study hypothesized that ill-being would be associated with higher levels of IL-6 and IL-6 receptor concentrations (sIL-6R) in plasma, and that well-being would be associated with lower levels, in otherwise healthy older individuals. One hundred and thirty five women ages 61 to 91 participated in this study and completed questionnaires in conjunction with having blood samples taken to measure IL-6 and sIL-6R concentrations in plasma.
Well-being in this study, as measured by answers to the questionnaires, was further broken down into eudaimonic and hedonic well-being. Eudaimonic well-being refers to 'engagement with the challenges of living' and was operationalized with scales assessing 'purpose in life,' 'self-acceptance' and other formulations of positive functioning. Hedonic well-being was assessed with the Positive Affect scale of the Mood and Anxiety Symptom Questionnaire (MASQ). Ill-being was also measured with scales from the MASQ.
Data analysis showed that only eudaimonic well-being measures were significantly associated with IL-6 levels; after health and sociodemographic factors were taken into account, associations between IL-6 levels and hedonic well-being or ill-being measures did not persist. This finding conflicts with previous research showing that ill-being has been associated with increases in IL-6 and sIL-6R. However, this study did not find a high prevalence of negative affect in the women; the fact that the study participants were generally healthy may limit the generalizability of these findings. Nevertheless, these data are consistent with a growing body of research highlighting the benefits for health of maximizing psychological well-being. These results also are consistent with findings that health, particularly in older people, can be strongly associated with feelings such as having personal control over events and achieving high-quality social ties.