CLINICAL COURSE OF NEUROPSYCHOLOGICAL FUNCTIONING AFTER CHRONIC EXPOSURE TO ORGANIC AND INORGANIC LEAD

This case series describes the clinical course (12- to 28-month follow -up) of neuropsychological functioning in 23 workers who had chronic o ccupational exposure to a mixture of organic and inorganic lead. Signi ficant improvement in performance was seen in 1/23 tests and deteriora tion in 3/23 tests. However there was no significant change in the maj ority of tests (19/23). Tests that showed deterioration were all tests of psychomotor/motor speed. In addition, 10 of 13 workers who complet ed a symptom checklist twice reported more frequent physical, cognitiv e, and affective symptoms at follow-up. This increase in symptoms was associated with psychomotor/motor slowing as compared to initial test performance. Many workers subjectively reported an increased frequency of memory and concentration problems at follow-up, although this chan ge could not be documented objectively individual worker demographic a nd exposure characteristics were not predictive of changes in neuropsy chological performance at retest. We propose a psychosocial mechanism to explain the increase in symptom severity and the psychomotor/motor slowing because environmental levels of lead declined during the inter -test interval. (C) 1997 National Academy of Neuropsychology.