Sandra Magalhaes1,2,3, Maura Pugliatti4,5, Trond Riise6,7, Kjell-Morten Myhr7,8, Antonio Ciampi2, Kjetil Bjornevik6,9, Christina Wolfson1,2,4. 1. Neuroepidemiology Research Unit, Research Institute of the McGill University Health Centre, Montreal, QC, Canada. 2. Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC, Canada. 3. Department of Sociology, University of New Brunswick, Fredericton, NB, Canada. 4. Department of Medicine, McGill University, Montreal, QC, Canada. 5. Department of Biomedical and Surgical Sciences, Unit of Clinical Neurology, University of Ferrara, Ferrara, Italy. 6. Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway. 7. National Multiple Sclerosis Competence Centre, Haukeland University Hospital, Bergen, Norway. 8. Department of Clinical Medicine, University of Bergen, Bergen, Norway. 9. Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
Abstract
BACKGROUND: Lower levels of sun exposure in childhood have been suggested to be associated with increased risk of multiple sclerosis (MS). In this paper we extend previous work, using two novel analytical strategies. METHODS: Data collected in the Environmental risk factors In MS (EnvIMS) study, a case-control study with MS cases and population-based controls from Canada, Italy and Norway, were used. Participants reported on sun exposure behaviours for 5-year age intervals from birth; we focused on the first three age intervals (≤15 years). We compared two life course epidemiology conceptual models, the critical period and the accumulation model. We also used latent class analysis to estimate MS risk for different latent sun exposure behaviour groups. RESULTS: The analyses included 2251 cases and 4028 controls. The accumulation model was found to be the best model, which demonstrated a nearly 50% increased risk of MS comparing lowest reported summer sun exposure with highest [risk ratio (RR) = 1.47 (1.24, 1.74)]. The latent sun exposure behaviour group, characterized by low sun exposure during summer and winter and high sun protection use, had the highest risk of MS; a 76% increased risk as compared with the group with high sun exposure and low sun protection use [RR = 1.76 (1.27, 2.46)]. CONCLUSIONS: Our analyses provide novel insights into the link between sun exposure and MS. We demonstrate that more time indoors during childhood and early adolescence is linked with MS risk, and that sun protection behaviours in those who spend most time indoors may play a key role in increasing risk.
BACKGROUND: Lower levels of sun exposure in childhood have been suggested to be associated with increased risk of multiple sclerosis (MS). In this paper we extend previous work, using two novel analytical strategies. METHODS: Data collected in the Environmental risk factors In MS (EnvIMS) study, a case-control study with MS cases and population-based controls from Canada, Italy and Norway, were used. Participants reported on sun exposure behaviours for 5-year age intervals from birth; we focused on the first three age intervals (≤15 years). We compared two life course epidemiology conceptual models, the critical period and the accumulation model. We also used latent class analysis to estimate MS risk for different latent sun exposure behaviour groups. RESULTS: The analyses included 2251 cases and 4028 controls. The accumulation model was found to be the best model, which demonstrated a nearly 50% increased risk of MS comparing lowest reported summer sun exposure with highest [risk ratio (RR) = 1.47 (1.24, 1.74)]. The latent sun exposure behaviour group, characterized by low sun exposure during summer and winter and high sun protection use, had the highest risk of MS; a 76% increased risk as compared with the group with high sun exposure and low sun protection use [RR = 1.76 (1.27, 2.46)]. CONCLUSIONS: Our analyses provide novel insights into the link between sun exposure and MS. We demonstrate that more time indoors during childhood and early adolescence is linked with MS risk, and that sun protection behaviours in those who spend most time indoors may play a key role in increasing risk.
Authors: Robert Zivadinov; Leo Iona; Luisa Monti-Bragadin; Antonio Bosco; Ante Jurjevic; Cristina Taus; Giuseppe Cazzato; Marino Zorzon Journal: Neuroepidemiology Date: 2003 Jan-Feb Impact factor: 3.282
Authors: Scott Sloka; Claudia Silva; William Pryse-Phillips; Scott Patten; Luanne Metz; V Wee Yong Journal: Can J Neurol Sci Date: 2011-01 Impact factor: 2.104
Authors: R M Lucas; A-L Ponsonby; K Dear; P C Valery; M P Pender; B V Taylor; T J Kilpatrick; T Dwyer; A Coulthard; C Chapman; I van der Mei; D Williams; A J McMichael Journal: Neurology Date: 2011-02-08 Impact factor: 9.910