POST-RADIATION NEUROCOGNITIVE DEFICIT IN THE CHORNOBYL CLEAN-UP WORKERS: GERIATRIC ASPECTS (part 2)

to investigate the psychophysiological characteristics of cognitive disorders in the long term after exposure to ionizing radiation in the elderly participants in the liquidation of the Chornobyl Nuclear Power Plant accident (Chornobyl cleanup workers).

Prospective clinical study with external and internal control. A randomized sample of elderly participants (attained age over 60 years) in the liquidation of the consequences of the accident at theChernobyl NPP (ChNPP) in 1986-1987 (Chornobyl cleanup workers) was examined from the Clinical andEpidemiological Registry (CER) of the National Research Center for Radiation Medicine (NRCRM) (main group, n = 52)with verified chronic cerebrovascular pathology. Comparison group (n = 13) - unexposed outpatients and inpatients/examinees of the Department of Radiation Psychoneurology of the Institute for Clinical Radiology (ICR) ofthe NRCRM. Internal control - cleanup workers, exposed at doses < 0.05 Sv (n = 12). Psychophysiological methods(auditory event related potentials (ERPs) P300 with topographic mapping), descriptive and variational statistics,parametric and nonparametric criteria, regressioncorrelation analysis were used.

According to P300, diffuse impairment of information and cognitive processes of the brain lateralized tothe left temporal region with a tendency to spread to the right frontal central region was detected in the maingroup. A significant dosedependent decrease in the amplitude of the cognitive component P300 in the left frontaltemporal region (r= - 0.65; p= 0.02) was found in the elderly cleanup workers exposed at doses exceeding 0.5 Sv.For the first time, a dosedependent increase in the P300 was detected was detected in the main group of cleanupworkers in the right temporal and posterior temporal regions: T4 (r= 0.31; p= 0.01), T6 (r= 0.28; p= 0.03).

The auditory ERPs P300 technique is informative for detecting and monitoring neurocognitive disorders in the elderly victims of the Chornobyl disaster. The use of modern, inexpensive, accessible, and noninvasivepsychophysiological methods for diagnosing neurocognitive disorders is advisable both in scientific research and inroutine clinical practice. Objective psychophysiological markers of post radiation neurocognitive deficits in the elderly have been identified for the first time. Initially, dosedependent changes in the temporal characteristics of theP300 component in the right (subdominant) hemisphere in the elderly Chornobyl accident survivors have been identified. These trends require further observation and study.