Individual differences in the temporal variability of medically unexplained symptom reporting

THEORY: Non-specific or medically unexplained symptoms account for up to 35% of outpatient referrals. In contrast to the literature on affect, little is known about how people frame daily symptoms and how these patterns are influenced by individual differences. METHOD: Three fixed occasion diary studies over an 8-day period (one on ill veterans of the Gulf War and two on healthy undergraduates) and a single cross-sectional survey (on ill Gulf War veterans) were conducted. The severity and frequency of daily symptoms were assessed in all daily diary samples, together with the Big 5 personality domains in one of the undergraduate samples and in the survey of veterans. The data were analysed using auto-correlations and hierarchical multivariate linear modelling. RESULTS: In all the chronically ill and healthy samples, the data suggested potential cyclical patterns for symptom severity reporting. With regard to the frequency of symptom reporting, the veterans showed a pattern of constant symptom reporting. Finally, the relationship between the reported severity of symptoms was attenuated by intellect and surgency. DISCUSSION: There is evidence that daily experiences of symptom severity are framed relative to each other and this relationship is influenced by personality. The practical implications of these findings are discussed.