BRAIN AND EYE AS POTENTIAL TARGETS FOR IONIZING RADIATION IMPACT. Part І. THE CONSEQUENCES OF IRRADIATION OF THE PARTICIPANTS OF THE LIQUIDATION OF THE CHORNOBYL ACCIDENT. / GOLOVNYI MOZOK TA ORGAN ZORU IaK POTENTsIINI MIShENI DLIa VPLYVU IONIZUIuChOGO VYPROMINIuVANNIa. Chastyna I. TsEREBROOFTAL'MOLOGIChNI EFEKTY OPROMINENNIa V UChASNYKIV LIKVIDATsIÏ NASLIDKIV AVARIÏ NA ChAES.

BACKGROUND: Exposure to ionizing radiation could affect the brain and eyes leading to cognitive and vision impairment, behavior disorders and performance decrement during professional irradiation at medical radiology, includinginterventional radiological procedures, long-term space flights, and radiation accidents. OBJECTIVE: The objective was to analyze the current experimental, epidemiological, and clinical data on the radiation cerebro-ophthalmic effects. MATERIALS AND METHODS: In our analytical review peer-reviewed publications via the bibliographic and scientometric bases PubMed / MEDLINE, Scopus, Web of Science, and selected papers from the library catalog of NRCRM - theleading institution in the field of studying the medical effects of ionizing radiation - were used. RESULTS: The probable radiation-induced cerebro-ophthalmic effects in human adults comprise radiation cataracts,radiation glaucoma, radiation-induced optic neuropathy, retinopathies, angiopathies as well as specific neurocognitive deficit in the various neuropsychiatric pathology including cerebrovascular pathology and neurodegenerativediseases. Specific attention is paid to the likely stochastic nature of many of those effects. Those prenatally and inchildhood exposed are a particular target group with a higher risk for possible radiation effects and neurodegenerative diseases. CONCLUSIONS: The experimental, clinical, epidemiological, anatomical and pathophysiological rationale for visualsystem and central nervous system (CNS) radiosensitivity is given. The necessity for further international studieswith adequate dosimetric support and the follow-up medical and biophysical monitoring of high radiation riskcohorts is justified. The first part of the study currently being published presents the results of the study of theeffects of irradiation in the participants of emergency works at the Chornobyl Nuclear Power Plant (ChNPP).

Depression and ionizing radiation.

The objective of this at issue paper is the analysis of published data in correlation with the results of own research on the potential role of ionizing radiation in the genesis of depressive disorders. Depression is one of the most significant and long-term effect of the atomic bombings, nuclear testing and radiation emergences. The participants of the accident at the Chornobyl nuclear power plant increased prevalence of depression (18.0% and 13.1% in controls) and suicide rates. Depression is mainly observed in the structure of an organic mental disorder against cerebrovascular disease. The clinical pattern is dominated by asthenoadynamic and asthenoapathetic depression. Depressive disorders in radiation emergencies are multifactorial, that is the result of exposure to the complex psychogenic and radiological accident's factors, impact of traditional risk factors, somatic and neurological diseases, genetic predisposition, predisposition, etc. At the same time, exposure to ionizing radiation is a factor in the genesis of depression. This impact can be direct (to the Central Nervous System), and indirectly through the somatic and neurological abnormalities (multiorgan dysfunction) as well as by a variety of pathogenic mechanisms of ionizing radiation on the brain that have been discovered recently. It is strongly necessary analytical clinical and epidemiological studies with verification of depression and evidence-based establishment of the role of radiation and non-radiation risk factors.

EEG patterns in persons exposed to ionizing radiation as a result of the Chernobyl accident: part 1: conventional EEG analysis.

Prospective conventional EEG study was carried out 3-5 and 10-13 years after the Chernobyl accident (1986) in patients who had acute radiation sickness and in emergency workers in 1986 ("liquidators"). Control groups comprised healthy volunteers; veterans of the Afghanistan war with posttraumatic stress disorder; veterans with mild traumatic brain injury; and patients with dyscirculatory encephalopathy. In 3-5 years after irradiation, there were irritated EEG changes with paroxysmal activity shifted to the left frontotemporal region (cortical-limbic overactivation) that were transformed 10-13 years after irradiation toward a low-voltage EEG pattern with excess of fast (beta) and slow (delta) activity together with depression of alpha and theta activity (organic brain damage with inhibition of the cortical-limbic system). Quantitative EEG is likely to be very informative for investigation of dose-effect relationships.

Schizophrenia spectrum disorders in persons exposed to ionizing radiation as a result of the Chernobyl accident.

We studied schizophrenia spectrum disorders in Chernobyl accident survivors by analyzing Chernobyl exclusion zone (EZ) archives (1986-1997) and by conducting a psychophysiological examination of 100 patients with acute radiation sickness (ARS) and 100 workers of the Chernobyl EZ who had worked as "liquidators-volunteers" for 5 or more years since 1986-1987. Beginning in 1990, there has been a significant increase in the incidence of schizophrenia in EZ personnel in comparison to the general population (5.4 per 10,000 in the EZ versus 1.1 per 10,000 in the Ukraine in 1990). Those irradiated by moderate to high doses (more than 0.30 Sv or 30 rem), including ARS patients, had significantly more left frontotemporal limbic and schizophreniform syndromes. We hypothesized that ionizing radiation may be an environmental trigger that can actualize a predisposition to schizophrenia or indeed cause schizophrenia-like disorders. The development of schizophrenia spectrum disorders in overirradiated Chernobyl survivors may be due to radiation-induced left frontotemporal limbic dysfunction, which may be the neurophysiological basis of schizophrenia-like symptoms. Persons exposed to 0.30 Sv or more are at higher risk of schizophrenia spectrum disorders. An integration of international efforts to discuss and organize collaborative studies in this field is of great importance for both clinical medicine and neuroscience.