Longitudinal neurocognitive assessments of Ukrainians exposed to ionizing radiation after the Chernobyl nuclear accident.

A 4-year longitudinal study of the cognitive effects of the Chernobyl nuclear accident was conducted from 1995 to 1998. The controls were healthy Ukrainians residing several hundred kilometers away from Chernobyl. The exposed groups included Eliminators, Forestry workers and Agricultural workers living within 150 km of Chernobyl. Accuracy and efficiency of cognitive performance were assessed using ANAMUKR, a specialized subset of the Automated Neuropsychological Assessment Metrics (ANAM) battery of tests. Analyses of variance, followed by appropriate pairwise comparisons, indicated that the 4-year averaged levels of performance of the exposure groups (especially the Eliminators) were significantly lower than those of the controls on most measures; further, analyses of performance across time revealed significant declines in accuracy and efficiency, as well as psychomotor slowing, for all exposed groups over the 4-year period. These findings strongly indicate impairment of brain function resulting from both acute and chronic exposure to ionizing radiation.