Cognitive effects of low dose of ionizing radiation - Lessons learned and research gaps from epidemiological and biological studies.

The last decades have seen increased concern about the possible effects of low to moderate doses of ionizing radiation (IR) exposure on cognitive function. An interdisciplinary group of experts (biologists, epidemiologists, dosimetrists and clinicians) in this field gathered together in the framework of the European MELODI workshop on non-cancer effects of IR to summarise the state of knowledge on the topic and elaborate research recommendations for future studies in this area. Overall, there is evidence of cognitive effects from low IR doses both from biology and epidemiology, though a better characterization of effects and understanding of mechanisms is needed. There is a need to better describe the specific cognitive function or diseases that may be affected by radiation exposure. Such cognitive deficit characterization should consider the human life span, as effects might differ with age at exposure and at outcome assessment. Measurements of biomarkers, including imaging, will likely help our understanding on the mechanism of cognitive-related radiation induced deficit. The identification of loci of individual genetic susceptibility and the study of gene expression may help identify individuals at higher risk. The mechanisms behind the radiation induced cognitive effects are not clear and are likely to involve several biological pathways and different cell types. Well conducted research in large epidemiological cohorts and experimental studies in appropriate animal models are needed to improve the understanding of radiation-induced cognitive effects. Results may then be translated into recommendations for clinical radiation oncology and imaging decision making processes.

Outcome of the European initiative for radiation protection research and future perspectives.

In 2009, the European Commission published the report of the high-level expert group that had been mandated to consider the scientific challenges posed by the issues of low dose effects of ionising radiation, and to formulate proposals for research policy evolution in this field at European level. This report formulated a first draft of a strategic research agenda. International scientific cooperation and an integrated approach are essential for the further development and enhancement of the international framework of radiation protection. This paper reflects on the results which have been gained through this integration approach: strategic research agendas have been established, policies and action plans have been developed for infrastructures and training education, several ambitious research projects have been launched, and a first draft of a European 'joint road map' for radiation protection research will be published. Reflecting on the challenges that lie ahead, this paper also presents the initiatives that the five European research platforms (MELODI: low dose research; ALLIANCE: radioecology; EURADOS: dosimetry; NERIS: emergency preparedness; EURAMED: radiation protection in medical applications) have jointly presented to the European Commission and Euratom member states to further enhance radiation protection research.