Neuropsychological toxicology of methylene diphenyl diisocyanate: a report of five cases.

The neuropsychological functioning of five men suffering alleged physical, cognitive and behavioural changes following exposure to methylene diphenyl diisocyanate (MDI), an industrial chemical, was investigated in the present study. At the time of assessment, four of the five patients remained symptomatic despite having no contact with MDI for periods ranging from 5 to 9 months. All patients reported experiencing subjective symptoms consisting of respiratory distress, headaches, depression, irritability, forgetfulness, decreased calculating ability, word-finding problems and reduced concentration. While the pattern of neuropsychological deficits varied among the patients, common findings for the group included intact psychomotor, psychosensory, visuographic and language functions accompanied by deceased concentration, mental efficiency, rate of information processing, learning ability and abstract reasoning. All five patients also revealed significant emotional distress on an objective personality measure. In general, the neuropsychological test data support the presence of behavioural and cognitive correlates of CNS injury following exposure to MDI.