jeudi 5 juin 2008

Angelina I. Nyagu: Mental health disorders after Chernobyl catastrophe

Mental health disorders after Chernobyl catastrophe

Professor Angelina I. Nyagu ( Ukraine)

Mental health disorders are one of the most important scientific and social problems of the post-Chernobyl period. In the liquidators radiation risks on non-cancer effects has been revealed. For some classes of non-cancer diseases among liquidators, statistically significant estimates of radiation risk were derived for the first time: mental disorders; neurological and sensory disorders; endocrine disorders. The highest excess relative risk per 1 Gy was found for cerebrovascular diseases.
According to the data of State Register of Ukraine there is an increased level of cerebrovascular disorders in liquidators and evacuees. Exposure to dose 250 mGy and more is a significant risk factor for neuropsychiatric disorders and vascular disorders. There is a dose–effect relationship for cerebrovascular disorders in liquidators. Progressive character of neuropsychiatric disorders and somatic pathology is observed in liquidators of 1986–1987, especially in those who worked for 3–5 years at the Chernobyl exclusion zone. Prevalence of neuropsychiatric disorders among personnel working since 1986–1987 and irradiated in doses above 250 mSv is 80.5% while for the same contingency, but irradiated in doses below 250 mSv — 21.4% (p<0.001).
Personnel of the Chernobyl exclusion zone who have been working since 1986 are the groups of highest risk of neuropsychiatric disorders (93—100%). Organic, including symptomatic, mental disorders (F00—F09) are dominating. A work and life in the Chernobyl exclusion zone since 1986 ten and more years later are leading toward a mental health deterioration to 3,4—6,2 times in comparison with a general population, and to 2—3,9 times — in comparison with survivors of military conflicts or natural disasters. Mental health deterioration in the personnel is in proportion to exposure dose and duration of work in the Chernobyl exclusion zone that may testify to a cumulative effect.
Neuropsychiatry and neuropsychophysiological follow-up studies confirm that Acute radiation Sickness (ARS) patients who survived after the Chernobyl disaster show progressive structural-functional brain damage: postradiation encephalopathy [postradiation organic brain syndrome]. There is the «dose–effect» relationship between the dose and the characteristic morphometric neuroimaging features of organic brain damage, starting with 0,3 Sv and increasing in proportion to the dose.
Considerable progress has been made in the last years concerning knowledge and understanding of the effects of ionizing radiation on the developing brain.
Individual dose reconstruction of the in utero exposed children was carried out considering internal and external exposure. The effective fetal doses (M±SD) in the exposed group was 65.4±33.9 mSv and in the control group 1.2±0.3 mSv. The equivalent in utero brain doses were 19.2±11.3 mSv and 0.8±0.2 mSv for the exposed and control group respectively. Especially high are the doses to the fetal thyroid: 760.4±631.8 mSv in the exposed and 44.5±43.3 mSv in the control group. The Intelligence Quotient measured by the Wechsler Intelligence Scale for Children (WISC) revealed a lower value of the verbal and therefore full scale IQ, as well as higher IQ discrepancies (pIQ-vIQ) due to verbal IQ deterioration in the exposed children from evacuee mothers of exclusion zone in comparison to children from mothers of Kiev. Prenatal exposed children have more neuropsychiatric disorders than the control children from Kiev for the following categories: 1) paroxysmal states; 2) organic mental disorders; 3) neurotic, stress-related and somatoform disorders; 4) disorders of psychological development; 5) childhood behavioral and emotional disorders, revealed by clinical examination using ICD 10.
The evacuated mothers experienced a high amount of real stress events (evacuation, lack of information about relatives, migration, difficulties of medical care). There are significant mental health problems in mothers from Pripyat in the following categories: 1) depression; 2) PTSD; 3) somatoform disorders; 4) anxiety/insomnia; 5) social dysfunction.

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