Neuropsychological impairment following inorganic arsenic exposure.

A 50-year-old chemical engineer, routinely screened for occupational arsenic exposure, was admitted with a delirium for which no known etiology was found. Elevated levels of arsenic were found in the urine and hair. The patient received chelation treatment with British anti-Lewisite; substantial amounts of arsenic were excreted and the toxic encephalopathy improved gradually over the 8-month follow-up period. The patient was tested at 6 weeks, 4 months, and 8 months postdelirium with a battery of neuropsychological tasks. The pattern of results showed verbal learning and memory to be severely impaired while tests of general intellectual abilities and language remained unaffected. Follow-up examinations with no subsequent reexposure revealed improvements on specific cognitive tasks. It is unclear whether recovery of cortical functions occurred or if compensatory strategies were developed. It is proposed that a subacute exposure to arsenic may have contributed to the neuropsychological deficits.