Impact of low-dose radiation on cognition and cerebrovascular system European scientists are combining experimental work with epidemiological data to identify the potential health risks associated with exposure to low-dose ionising radiation. Health © Thinkstock Exposure to ionising radiation is linked to cancer development. However, at low doses, other potential risks such as effects on brain development and cerebrovascular disease have been largely neglected. In particular, exposure to radiation in utero, or as a result of the Chernobyl accident or childhood cancer radiotherapy, needs to be assessed to determine the risk of developing cerebrovascular diseases. The key objective of the EU-funded 'Cognitive and Cerebrovascular Effects Induced by Low Dose Ionising Radiation' (CEREBRAD) project is to investigate the long-term cognitive and cerebrovascular risks of low-dose ionising radiation. So far, the consortium has collected data from Chernobyl liquidators as well as in utero-exposed subjects. Interviews of the postnatal-exposed cohort showed preliminary data that indicated mild cognitive impairment in nearly 40 % and vascular dementia in 15 % of the cases. Cognitive and neuropsychological tests on radiotherapy patients treated for haemangioma and having received low-dose radiation to the brain are ongoing. This data is being combined with experimental studies in animals receiving different doses of ionising radiation. Using specific behaviour tests, researchers have analysed the cognitive and cerebrovascular effects of low-dose radiation. Despite the fact that that preliminary data indicate a dose threshold below which no severe cognitive impairment could occur, subtle changes in working strategy and other functions related to the pre-frontal cortex appear to be modulated at low doses. At the molecular level, radiation has been found to cause neuro-inflammation and glial activation that perturbs neuronal equilibrium and impairs neurogenesis. Dosimetric investigations on animal foetuses indicate that the energy deposited in soft tissue and bone is dependent on whether the radiation source is internal or external. In light of the observed radiation response, the role of combined exposure with environmental pollutants will also be assessed. Taken together, the activities of the CEREBRAD study will determine the outcome of low-dose radiation and help calculate organ doses after partial or whole-body irradiation. The generated scientific evidence will be used to inform the radiation protection communities and regulatory bodies about the long-term risks associated with low-dose radiation.
