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.