NEUROPHYSIOLOGICAL BASIS OF THE COMBINED EFFECTS OF ACUTE STRESS AND LOW DOSES OF IONIZING RADIATION ON HUMAN BRAIN

Abstract

Objective: to study the clinical and neurophysiological features in the Chornobyl clean-up workers with a verified chronic cerebrovascular disease/cerebral small vessels disease (SVD) exposed to low doses of ionizing radiation (IR), employees of the Chornobyl Nuclear Power Plant (SSE ChNPP), who were exposed to the stress factor of a full-scale war as a result of being held captive by the Russian military at their workplaces, and individuals of the non-irradiated comparison group. Design, object and methods. A cross-sectional clinical study with parallel external control groups. We studied and carried out an expert statistical analysis of the clinical and neurophysiological characteristics of 62 male subjects, from which three examination groups were formed: 1) a randomized sample from the Clinical Epidemiological Register (CER) of the State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine» (NRCRM) of 22 Chornobyl clean-up workers (‘Chornobyl liquidators’) in 1986–1990, examined during 2020–2021, aged 50–68 years at the time of examination (M ± SD: (58.1 ± 5.2) years) with a documented external radiation dose of 0.03–2.30 Sv; 2) 24 SSE ChNPP employees exposed to the stress factor impact of a full-scale war as a result of being held captive by the Russian military at their workplaces. The average age of the examined was (54.5 ± 5.8) years (range 46–71 years). 3) Comparison group – 16 non-exposed men with verified chronic cerebrovascular disease/cerebral small vessels disease (SVD). The average age of the examined was (57.8 ± 5.6) years (range 50–70 years). Results. Neurophysiological studies confirm the presence of the pronounced dysfunction of the cortico-limbic system of the left dominant hemisphere of the brain with special involvement of the hippocampus in the Chornobyl clean-up workers. In the SSE ChNPP group, for the first time, the disorders of cerebral neurodynamics were detected in the form of functional hypofrontality and hyperfunction of the cortico-limbic system with lateralization to the right hemisphere. Conclusions. Today there exists a long-term thorough methodological and evidence base for a possible neurophysiological diagnosis and differential diagnosis of the combined cerebral effects of IR and psycho-emotional stress associated with the conditions of military conflicts. Neurophysiological technologies can be used in the objective professional and qualification selection of employees in a number of professions that require quick and responsible decision-making. Employees of SSE ChNPP need further medical and psychological support due to an increased risk of developing mental health disorders. Key words: Chornobyl disaster, ionizing radiation, clinical neurophysiology, quantitative EEG, cerebral small vessel disease, PTSD, military conflicts.