Somatic and mental distress as predictors of number of symptoms associated with environmental factors in an adult general population: Cross-sectional and longitudinal findings.

OBJECTIVE: Hypotheses were tested of associations between indicators of somatic and mental distress and number of different types of environmental intolerances, referred to as symptoms attributed to environmental factors (SAEFs), and these indicators predicting development of additional SAEFs in a general population. The SAEFs regarded chemicals, buildings, electromagnetic fields and sounds.

METHODS: Data were used from a Swedish population-based sample of 2336 adults. Cross-sectional and 3-year longitudinal analyses were conducted based on validated questionnaire instruments assessing somatic symptom distress, perceived stress, anxiety and depression.

RESULTS: Prevalence percentage of the SAEFs ranged from 2.1 % to 13.4 %; 16.2 % had one SAEF, 4.9 % had two SAEFs, and 1.2 % had three or four SAEFs. Cross-sectionally, Kendall rank correlation analyses and ANOVAs showed that somatic symptom distress (rtau-b = 0.214), perceived stress (rtau-b = 0.137), anxiety (rtau-b = 0.145) and depression (rtau-b = 0.100) increased with number of SAEF. In the longitudinal analysis, all four indicators were found to be predictors of an increase in number of SAEFs three years later (odds ratios = 1.021-1.049 for each scale step), with somatic symptom distress as the strongest predictor.

CONCLUSION: The results suggest that all four types of SAEFs are associated with all four indicators of negative affectivity, and that the level of these indicators is associated with number of SAEFs and predict development of additional SAEFs. Among the studied indicators, somatic symptom distress appears to be particularly associated with development of multiple SAEFs, perhaps driven by the motive to find a cause for bothersome symptoms (misattribution).