Aims: The aims of the study were to analyze the type and size of deficit scores and the weight attached to symptoms in the diagnostic process for a group of patients diagnosed as having chronic solvent encephalopathy (CSE) at a time when exposure levels were high and financial incentives for CSE-sufferers were almost non-existent.
Methods: Forty-eight patients referred for possible CSE and 144 age-matched referents were tested with neuropsychological tests. Symptoms were recorded using the Q16. The WHO 1985 recommendations were used when assessing the outcome of the test results. All the subjects were men in manual occupations.
Results: Thirty-five patients were diagnosed as having CSE; the remaining 13 not so. The tests for cognitive speed and attention were the ones that discriminated best between the patients with CSE and their referents. The effect sizes of the neuropsychological tests were small to moderate, and the largest effect size (d=0.81) was found for the WAIS Digit Symbol. The effect size of the difference between the CSE-group and their referents in terms of self-reported symptoms was large (d=3.35). For the non-CSE-group the differences between patients and referents were smaller and non-significant. However, the effect size in terms of symptoms was almost as large among the non-CSE-group as among the patients diagnosed as having CSE.
Conclusions: The patients reported many symptoms but the neuropsychological tests showed only slight to moderate impairment of function. The similarity of the large effect size for symptoms, but different effect sizes for neuropsychological tests results between the CSE-group and non-CSE-group suggest symptoms were (and still are) not very useful in the diagnostic process of CSE. Objective testing with neuropsychological tests is necessary for diagnosis of CSE.