Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)




Influenza results in substantial human suffering and health care costs. Evidence from psychoneuroimmunology suggests that emotions influence the immune system and may alter susceptibility to infectious diseases, like influenza. The purpose of this investigation was to evaluate the influence of psychological factors, health behaviors, circulating levels of proinflammatory cytokines and the development of influenza-like illness in older adults. Medically stable participants, 55 years of age and over, were enrolled from the general community and an elderly community. Psychological factors (emotions and perceived stress), health behaviors (sleep and physical activity) and plasma cytokine levels (IL-6 and IL-1B) were evaluated with respect to the development of influenza-like illness over the course of the influenza season (October to March 31, 2011). Findings revealed that individuals reporting influenza-like symptoms were significantly younger than those who did not report symptoms (60 versus 72 years). These individuals reported lower positive trait emotion scores on the Positive and Negative Affect Scale (PANAS), with significantly lower scores for the calm subscale for trait emotions. Those with influenza-like symptoms reported significantly higher levels of perceived stress, greater amounts of physical activity and less sleep disturbance. For cytokine measurements, significantly lower circulating IL-6 levels were observed at initial assessment for those with influenza-like symptoms. No differences were observed between groups for IL-1B. Lower calm trait subscales approached significance for predicting increased IL-1B in plasma, suggesting a role for lower positive emotions and stress perception as risk factors for influenza-like illness in older adults. These results suggest a role for lower positive emotions and stress perception as risk factors for influenza-like illness in older adults. Further, these results support the need for additional study to evaluate potential mechanisms that may underlie these risks. Significant increases in positive trait emotions scores were associated with increasing age, higher Ego Resiliency scores, fewer reported sleep problems, and lower Percieived Stress scores. An ad hoc mediator analysis was significant for positive trait emotion scores mediating the relationship between scores for ego resiliency and percieved stress. This finding supported a direct and indirect role for positive emotions to reduce perceived stress.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.