Poster(s)
The mean is not the measure: variability in morning daily immune levels relate to perceived stress
M. Bristow
Anglia Ruskin University
R. Cook
Anglia Ruskin University
M. Edwards
Anglia Ruskin University
Background
Research which has examined the relationship between ‘chronic’ stress and immunoglobulin A (IgA) secretion has tended to use mean IgA secretion as the measure of choice. However, there is substantial variation in daily IgA levels which perhaps should not be treated as error to be removed by averaging. In this study we used the Relative Standard Deviation (RSD%) as a measure of IgA stability over time in both the morning and evening and related this to measures of stress, distress and social support.
Methods
48 participants provided unstimulated saliva samples after waking in the morning and in the evening for five consecutive days. Participants completed questionnaires assessing levels of stress, distress and social support over the past month. Saliva samples were analysed for IgA using an in-house double sandwich ELISA.
Results
Neither mean morning nor evening IgA secretion rate was related to stress, distress or social support. Mean IgA secretion rate, whether assessed in the morning or evening, was not related to stress, distress or social support. However, morning IgA secretion rate stability was significantly inversely correlated with perceived stress (r=-.352, n=35, p <.05), distress (-.431, n=35, p <.01) and positively correlated with social support (r=.388, n=34, p <.5). There was no relationship between evening IgA stability and psychological variables.
Conclusion
Individuals who have experienced higher levels of stress, distress or lower levels of social support have less stability in their morning IgA secretion rate but there was no evidence of a difference in their mean IgA secretion. The often high levels of instability in participants’ daily IgA secretion may not be merely error that needs removing but might instead be an important aspect of stress– mucosal immune function.
