Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Original Paper Neuroepidemiology 2009;32:81–88 DOI: 10.1159/000177032 Geographical Clustering of Amyotrophic Lateral Sclerosis in South-East England: A Population Study Kirsten M. Scott a Kumar Abhinav b Biba R. Stanton b Clare Johnston b Martin R. Turner b Mary-Ann Ampong c Mohamed Sakel e Richard W. Orrell d Robin Howard d Christopher E. Shaw b P. Nigel Leigh b Ammar Al-Chalabi b a King’s College Medical School at Guy’s, King’s College and St. Thomas’s Hospitals, b MRC Centre for Neurodegeneration Research, Institute of Psychiatry, King’s College London, c King’s College Hospital, d The National Hospital for Neurology and Neurosurgery, London, and e Neurorehabilitation Unit, Buckland Hospital, East Kent Hospitals Trust, Dover , UK London. SaTScan identified an area that had a 5.61-km radius in which the relative risk of ALS was 1.70 (p = 0.012). This area overlapped with the postcode districts and some of the sec- tors identified using the residuals method. Conclusions: These findings suggest an excess of ALS cases in some post- code districts in south-east England. Copyright © 2008 S. Karger AG, Basel Introduction Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that results in loss of motor functions and eventual death from respiratory failure, usually within 3 years of symptom onset. The incidence of ALS peaks between 50 and 70 years of age and it is gen- erally more common in men. The overall global annual incidence is between 0.07 and 2.6 per 100,000 person- years [1]. The lifetime risk is about 1 in 400 [2], but, be- cause of the appalling prognosis, it is still regarded inap- propriately as a rare disease. In about 10% of cases there is a family history of ALS that is often consistent with au- tosomal dominant inheritance [3] . Anecdotal evidence Key Words Amyotrophic lateral sclerosis  Motor neuron disease  Geographical distribution  Population study Abstract Background: Amyotrophic lateral sclerosis (ALS) is a degen- erative disease of motor neurons that causes progressive pa- ralysis and eventually results in death from respiratory fail- ure. Environmental factors that trigger ALS might result in a pattern of geographical clustering of cases. We tested this hypothesis using the South-East England ALS population register, which covers south-east London, Kent and parts of neighbouring counties. Methods: The register’s catchment area was divided into postcode districts and sectors. The ex- pected rates of ALS (adjusted for age and sex) were com- pared with the observed rates using a standardised residuals method and the SaTScan programme. Results: There were 406 cases of ALS identified in the catchment area during the study period. Four of the 126 postcode districts, all in Great- er London, had residuals 12.5 SDs from the mean. Similarly, there were 15 postcode sectors (out of 420) that had residu- als 11.96 SDs from the mean. Nine of these were in Greater Received: March 16, 2008 Accepted: July 16, 2008 Published online: November 27, 2008 Prof. Ammar Al-Chalabi MRC Centre for Neurodegeneration Research King’s College London Institute of Psychiatry P 043, London SE5 8AF (UK) Tel. +44 20 7848 5172, Fax +44 20 7848 5190, E-Mail ammar@iop.kcl.ac.uk © 2008 S. Karger AG, Basel 0251–5350/09/0322–0081$26.00/0 Accessible online at: www.karger.com/ned © For permitted use only. ANY FURTHER DISTRIBUTION OF THIS ARTICLE REQUIRES WRITTEN PERMISSION FROM S. KARGER AG BASEL AND MAY BE SUBJECT TO A PERMISSION FEE