Unravelling determinants of symptoms associated with environmental factors over time: Results from a representative sample.

Symptoms associated with environmental factors (SAEF) are associated with behavioral and emotional reactions towards environmental factors, modern health worries, botheredness with these factors, and heightened somatic symptom burden. While all these constructs play a part in SAEF, it is unclear how they relate to each other over time. The aim of this study was to unravel determinants of SAEF and compare them with those observed in healthy individuals. We used a longitudinal population-based Swedish dataset with three timepoints (N = 1576), in which we conducted lag-2 cross-lagged panel models. Modern health worries (MHWS) and negative behavioral and emotional reactions towards the environment predicted botheredness with environmental factors from Time 1 to Time 2 (from MHWS: β = 0.05, 95% CI = [0.01; 0.10], p = .02; from reactions: β = 0.14, 95% CI = [0.10; 0.19], p < .001) and vice versa (to MHWS: β = 0.07, 95% CI = [0.02; 0.13], p = .009; to reactions: β = 0.14, 95% CI = [0.10; 0.19], p < .001). Physical symptoms were predicted by botheredness with environmental factors and modern health worries at Time 2, but at Time 3 physical symptoms were no longer predicted by any of the other constructs. When testing the model on individuals with SAEF vs. healthy individuals, we found that the paths are mostly equally strong in both groups (χ2 difference = 37.42, df = 27, p = 0.087), but that the clusters differed in their levels of the variables (χ2 difference = 569.52, df = 9, p <0.001). In conclusion, this study suggests that cognitive, emotional and behavioral features of SAEF are mutually dependent, and participate in a vicious circle that perpetuate symptoms, which speaks in favor of nocebo effects contributing to SAEF and opens avenues for treatment.