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Neuropsychological Status of Persons Exposed in Uteri

#B-835


Investigation of Intellectual Development, Mental and Behavioural Disorders in Persons Exposed in Utero from Chernobyl Fallout (Case-Control Study)

Tech Area / Field

  • MED-OTH/Other/Medicine

Status
3 Approved without Funding

Registration date
04.12.2001

Leading Institute
Institute of Power Engineering Problems, Belarus, Minsk, Sosny

Supporting institutes

  • Belarusian Medical Academy for Postgraduate Education, Belarus, Minsk

Project summary

The Project goal:

Investigation of intellectual development, mental and behavioural disorders in persons exposed in utero from Chernobyl fallout.

Background:

Radiation accidents can have profound psychosocial effects on inpiduals, families and communities. It is evident from recent experience and research that psychosocial impacts can be among the most significant consequences of radiation accidents. (WHO. Health Consequences of the Chernobyl Accident: Results of the IPHECA Pilot Projects and Related National Programs. Summary Report. Geneva, 1995). Accidental radiation exposure of pregnant women is always a source of great concern and anxiety. Deterministic effects from ionizing radiation during pregnancy include a wide range of effects, including lethality, central nervous system abnormalities, cataracts, growth retardation, malformations, and even behavioral disorders. Since the fetal neural system is most sensitive and has the longest period of development, radiation-induced abnormalities are rarely seen in humans without mental and behavioural disorders (Otake M., Schull W.J., Lee S. Threshold for radiation-related severe mental retardation in prenatally exposed A-bomb survivors: a re-analysis. Int.J.Radiat. Biol. 1996; 70: 755763).

The accident at the nuclear power plant in Chernobyl in northwestern Ukraine, on April 26, 1986, released large amounts of radioactive materials. Of particular concern were the releases of 1.3 to 1.8 exabecquerels (35-50 million curies) of 131I plus other shorter-lived radioiodines (IAEA. Summary of the Conference Results. Pages 3-17 in: One Decade after Chernobyl. Summing up the Consequences of the Accident. Proceedings of an International Conference. Vienna, 8-12 April 1996). The radioactive cloud from the destroyed reactor, which reached the territory of Belarus within a few hours after the accident, resulted in population exposure, in particular rather high external doses and internal doses to the thyroids.

The factors that might cause mental and behavioural disorders were prenatal exposure from g-emitted radionuclides and internal exposure to the thyroid gland from radioiodines. In particular, the absorbed doses are 2-3 times higher in the developing thyroid gland of embryo and fetus than in the thyroid gland of the mother. Radiation affecting the thyroid gland leads to involvement of other endocrine glands in the pathological process through the thyroid gland-hypophysis-hypothalamus system. This may cause psychological retardation, retardation of the central nervous system maturation, low psychological and emotional development and other mental disorders. From the other hand, some unfavorable psychosocial factors such as forced relocation or adaptation to new conditions of living in the contaminated area could lead to the psychoemotional stress in parents, and affected family relations. The educational process can also lead to “psychosocial isolation” of relocated persons. Thus, in estimating the influence of the Chernobyl accident and its effects on the neuropsychological status of persons, it is necessary to take into account both pre- and postnatal exposure and other exogenic factors, and psychosocial factors.

Impact of the Project on the progress:

The proposed Project gives the unique opportunity to investigate in dynamic mental health in persons exposed in utero and estimate age-dependent risk of mental and behavioural disorders caused by the radiation and social factors following an accident at the nuclear facility. The given Project allows to estimate prenatal exposure levels among childhood population following the Chernobyl accident. Results of proposed Project will be further of progress in public health, radiobiology, and radiation protection of population.

Project participants:

Two organizations participate in the Project: Institute of Power Engineering Problems (IPEP) and Belarusian Medical Academy for Postgraduate Education (BMAPE).

IPEP will co-ordinate the project activity. It will take responsibility for the inpidual dose reconstruction for prenatal exposed persons. Together with the partners from BMAPE IPEP will participate in comprehensive analysis of clinical and dosimetry data obtained and estimation of risk of mental and behavioural disorders among in utero exposed persons.

BMAPE will take responsibility for the clinical, psychological and neurophysiological examinations of persons included in study as well as for the analysis of data obtained and estimation of risk of mental and behavioural disorders among in utero exposed persons.

Project participants are specialists who worked in sphere of design, construction, performance and operation of nuclear reactors, nuclear power engineering, radioecology, dosimetry, radiobiology, psychology and psychiatry, computer-technology.

Expected results:

This research concerns to a category of basic research. The following results will be archived within 4 tasks of given Project:

– Neuropsychological status among person included in study.


– Intellectual development as well as prevalence rate of mental and behavioural disorders among persons of exposed and control groups.
– Inpidual doses among childhood population exposed in utero following the Chernobyl accident.
– Clinical and dosimetry data that will allow evaluating relative risk of mental and behavioural disorders in persons exposed in utero.

Results of the Project allow to obtain new knowledge in the field of public health and radiation protection. Results of Project allow obtaining data and statistics that will be further of progress in public health, radiobiology, and radiation protection of population. Estimation of relative risk coefficient of mental and behavioural disorders among the population exposed to radiation will be further of progress in radiobiology.

Application of Project results:

The Project results will allow to assess a relationship between mental and behavioural disorders among persons and radioecological and psychosocial factors caused by the Chernobyl accident;

– The Project results allow to estimate the relative risk of mental and behavioural disorders in persons exposed in utero.


– With the use of the Project results the radiological consequences of Chernobyl accident will be assessed more accurately.
– The Project results could be used as a basis for planning of the radiation protection measures in the case of accidents on the nuclear installations.

Meeting ISTC goals:

– The Project gives the possibility to scientists connected with military researches for reorientation of the gains on peace activity by means of investigation of radiological consequences of the Chernobyl accident.


– The Project allows the Project participants to be integrated in the international scientific community by means of establishing of scientific communications through Collaborators.
– The Project supports basic research for peaceful purposes in the field of radiobiology and of radiation protection of the population in countries suffering from the consequences of the accident at the Chernobyl NPP.
– The Project contributes to the solution in one of the fundamental problems in radiobiology: estimation the risk coefficient among exposed population.

Scope of activities:

The Project is anticipated to be completed in 30 month. Two organizations participate in the Project: IPEP and BMAPE. The Project work includes the following task:

Task 1. Clinical, psychological and neurophysiological (EEG) examinations of persons of exposed and control groups.

Task 2. Estimation of intellectual development, diagnostics of mental and behavioural disorders in persons.

Task 3. Development of models for the reconstruction of the prenatal doses. Assessment of inpidual prenatal doses from external exposure and internal thyroid exposure to foetus.

Task 4. Comprehensive analysis of data obtained following the clinical, psychological, neuropsychological examination and dosimetric data. Evaluating of relative risk of mental and behavioural disorders among persons exposed in utero.

Role of Foreign Collaborators:

– information exchange in the course of Project implementation;


– provide comments to the technical reports, submitted by Project participants to the ISTC;
– cross-checks of results obtained in the course of Project implementation;
– testing and evaluation of methodology and results obtained within the framework of the Project;
– assistance for Project participants to join international meetings;
– conduction of joint seminars and workshops.

Technical approach and methodology.

The leading institution in the project is IPEP. This institution has a big experience in the field of the radioecology of nuclear power engineering. It has been involved in investigation of radiological consequences of the nuclear accidents and dose estimates for many years. Second participating institution is BMAPE that is involved for the in the investigation of health consequences of the Chernobyl accident.

Within Task 1 the clinical, psychological and neurophysiological (EEG) examinations will be carried out for the two groups of persons. The exposed group is 250 persons, born between May 1986 and February 1987. During the Chernobyl accident their pregnant mothers lived in the settlements where 137Cs soil deposition densities ranged from 100 to 15,400 kBq×m-2. After the accident families with children were evacuated from the contaminated settlements. The control group is formed by random selection and consisted of 250 children born between May 1986 and February 1987. Their mothers had constantly lived in Belarus settlements with low and slightly 137Cs deposition. The psychiatric examination of children from both groups will be performed by means of semi-structured clinical interview based on the diagnostical criteria of ICD-10, chapter V. Neurophysiological examinations will be carried using electroencephalograph "Nihon Kohden" EEG-7314.

To carry out Task 2 the intellectual development of these children will be examined by means of psychological testing using the Wechsler Intelligence Scale for Children - WISC-III UK. The investigation of learning disorders will be conducted with stardartized test “The method of early revealing of dyslexia”. The studying of microsocial surrounding of children, analyzing of situational and personal anxiety of parents and comparing the education level of parents will be also performed.

To reconstruct inpidual doses to foetus within Task 3 the appropriate methods will be developed and verified. The main considered pathways will be the following: external exposure from g-emitted radionuclides deposited on ground surface and internal thyroid exposure from radioiodine. Thyroid doses for person exposed in utero will be reconstructed from the results of inpidual thyroid dose estimates for the mother, and from a transfer coefficient from mother to the foetus that takes into account the period of gestation at the time of exposure. To estimate the inpidual doses and to obtain information about the life-style of the mother during the post-accident period the personal dosimetry interview will be conducted.

Within the framework of Task 4 collected clinical information, results of psychological and neurophysiological examinations, and results of personal dosimetry interview will be stored in electronic form. For comprehensive analysis of data obtained the statistical methods will be used. Mean values will be compared by analysis of variance and by t test. For 2×2 comparisons the c2 test will be used. To assess a relationship between mental and behavioural disorders among persons and radioecological and psychosocial factors the regression and correlation analysis will be applied. To estimate relative risk the odds ratios will be calculated.


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