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Effect of low doses of ionising radiation in infancy on cognitive function in adulthood: Swedish population based cohort study

BMJ 2004; 328 doi: (Published 01 January 2004) Cite this as: BMJ 2004;328:19
  1. Per Hall (Per.Hall{at}, associate professor1,
  2. Hans-Olov Adami, professor1,
  3. Dimitrios Trichopoulos, professor2,
  4. Nancy L Pedersen, professor1,
  5. Pagona Lagiou, assistant professor3,
  6. Anders Ekbom, professor1,
  7. Martin Ingvar, professor4,
  8. Marie Lundell, hospital physicist5,
  9. Fredrik Granath, biostatistician1
  1. 1 Department of Medical Epidemiology and Biostatistics, Karolinska Institute, PO Box 281, SE-171 77 Stockholm, Sweden
  2. 2 Department of Epidemiology, Harvard Center for Cancer Prevention, Harvard School of Public Health, 677 Huntington Avenue, Boston MA 02115, USA
  3. 3 Department of Hygiene and Epidemiology, School of Medicine, University of Athens, Greece
  4. 4 Department of Clinical Neuroscience, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
  5. 5 Department of Hospital Physics, Karolinska University Hospital
  1. Correspondence to: P Hall
  • Accepted 1 October 2003


Objective To determine whether exposure to low doses of ionising radiation in infancy affects cognitive function in adulthood.

Design Population based cohort study.

Setting Sweden.

Participants 3094 men who had received radiation for cutaneous haemangioma before age 18 months during 1930-59.

Main outcome measures Radiation dose to frontal and posterior parts of the brain, and association between dose and intellectual capacity at age 18 or 19 years based on cognitive tests (learning ability, logical reasoning, spatial recognition) and high school attendance.

Results The proportion of boys who attended high school decreased with increasing doses of radiation to both the frontal and the posterior parts of the brain from about 32% among those not exposed to around 17% in those who received > 250 mGy. For the frontal dose, the multivariate odds ratio was 0.47 (95% confidence interval 0.26 to 0.85, P for trend 0.0003) and for the posterior dose it was 0.59 (0.23 to 1.47, 0.0005). A negative dose-response relation was also evident for the three cognitive tests for learning ability and logical reasoning but not for the test of spatial recognition.

Conclusions Low doses of ionising radiation to the brain in infancy influence cognitive abilities in adulthood.


  • Contributors PH initiated and planned the study and was mainly responsible for data collection, interpretation of results, and writing the paper. H-OA, DT, PL, and AE participated in the interpretation of results and writing the paper. NLP provided the necessary psychological skills for interpretation of the test results for intelligence, planned the study, and wrote the paper. MI provided the neurocognitive knowledge for interpretation of results and participated in the planning of the project. ML was responsible for dose calculations and planning of the initial phase of the study. FG had overall responsibility for risk analyses and participated in planning and conducting the study. PH and FG will act as guarantors for the paper

  • Funding The European Commission (contract No FIGH CT 19990007).

  • Competing interests None declared.

  • Ethical approval This project was granted ethical approval by the Data Inspection Board in Sweden, 1997.

  • Accepted 1 October 2003
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