Multiple sclerosis risk has been shown to have seasonal variations that are more pronounced in higher latitudes. However, this phenomenon has not been adequately studied near the Equator.
Objective:
To explore the risk of multiple sclerosis associated with month, season of birth, and sunlight exposure variables in Colombia.
Methods:
In this case–control study, 668 multiple sclerosis cases were matched to 2672 controls by sex and age. Association of multiple sclerosis with each month/season of birth and sunlight exposure variables was estimated with multilevel mixed-effects logistic regression and ecological regression models, respectively. Seasonality in the births of multiple sclerosis was assessed with a non-parametric seasonality test.
Results:
We found a higher probability of multiple sclerosis in September (0.25; 95% confidence interval (CI) = 0.21–0.31) and lower in March (0.15; 95% CI = 0.10–0.18), which turned non-significant after a multiple comparisons test. Sunlight exposure variables had no significant effect on the risk of MS, and the tests of seasonality in the births of MS did not show significant results.
Conclusion:
Our results show no seasonality in the risk of multiple sclerosis near the Equator, supporting the hypothesis that this phenomenon is latitude dependent.
DobsonRGiovannoniGRamagopalanS.The month of birth effect in multiple sclerosis: Systematic review, meta-analysis and effect of latitude. J Neurol Neurosurg Psychiatry2013; 84(4): 427–432.
2.
PantavouKGBagosPG.Season of birth and multiple sclerosis: A systematic review and multivariate meta-analysis. J Neurol2020; 267(10): 2815–2822.
3.
BeckerJCallegaroDLana-PeixotoMA, et al. Season of birth as a risk factor for multiple sclerosis in Brazil. J Neurol Sci2013; 329(1–2): 6–10.
4.
FragosoYDAdoniTGarcia de AlmeidaSM, et al. Multiple sclerosis in South America: Month of birth in different latitudes does not seem to interfere with the prevalence or progression of the disease. Arq Neuropsiquiatr2013; 71(9A): 573–579.
5.
FragosoYDShearerKDAdoniT, et al. Month of birth does not seem to interfere with the development of multiple sclerosis later in life in Brazilian patients. Neuroepidemiology2012; 39: 70–71.
6.
Kazemi MoghadamVDickersonASShahediF, et al. Association of the global distribution of multiple sclerosis with ultraviolet radiation and air pollution: An ecological study based on GBD data. Environ Sci Pollut Res Int2021; 28(14): 17802–17811.
7.
TremlettHZhuFAscherioA, et al. Sun exposure over the life course and associations with multiple sclerosis. Neurology2018; 90(14): e1191–e1199.
8.
LamTVoPhamTMungerKL, et al. Long-term effects of latitude, ambient temperature, and ultraviolet radiation on the incidence of multiple sclerosis in two cohorts of US women. Environ Epidemiol2020; 4(4): e0105.
9.
Espinosa-RamírezGOrdoñezGFlores-RiveraJ, et al. Sunlight exposure and multiple sclerosis in a tropical country. Neurol Res2014; 36(7): 647–650.
10.
McDowellTYAmrSLangenbergP, et al. Time of birth, residential solar radiation and age at onset of multiple sclerosis. Neuroepidemiology2010; 34(4): 238–244.
11.
VitkovaMDioufIMalpasC, et al. Association of latitude and exposure to ultraviolet B radiation with severity of multiple sclerosis. Neurology2022; 98(24): e2401–e2412.
12.
D’hoogheMBHaentjensPNagelsG, et al. Sunlight exposure and sun sensitivity associated with disability progression in multiple sclerosis. Mult Scler2012; 18(4): 451–459.
13.
StaplesJPonsonbyALLimL.Low maternal exposure to ultraviolet radiation in pregnancy, month of birth, and risk of multiple sclerosis in offspring: Longitudinal analysis. BMJ2010; 340: c1640.
14.
VerheulFSmoldersJTrojanoM, et al. Fluctuations of MS births and UV-light exposure. Acta Neurol Scand2013; 127(5): 301–308.
15.
GryttenNTorkildsenØAarsethJH, et al. Month of birth as a latitude-dependent risk factor for multiple sclerosis in Norway. Mult Scler2013; 19(8): 1028–1034.
16.
Jiménez-PérezCZarco-MonteroLCastañeda-CardonaC, et al. Estado actual de la esclerosis múltiple en Colombia. Acta Neurológica Colomb2015; 31(4): 385–390.
17.
ThompsonAJBanwellBLBarkhofF, et al. Diagnosis of multiple sclerosis: 2017 revisions of the McDonald criteria. Lancet Neurol2018; 17(2): 162–173.
18.
MirmosayyebOBarzegarMAfshari-SafaviA, et al. Evaluation of month of birth in neuromyelitis optica spectrum disorders (NMSOD) and multiple sclerosis (MS). Mult Scler Int2021; 2021: 8874999.
19.
ProcopioMMarriottPKDaviesRJ.Seasonality of birth in epilepsy: A southern hemisphere study. Seizure2006; 15(1): 17–21.
20.
BrennerAVLinetMSShapiroWR, et al. Season of birth and risk of brain tumors in adults. Neurology2004; 63(2): 276–281.
21.
PamphlettRFangF.Season and weather patterns at time of birth in amyotrophic lateral sclerosis. Amyotroph Lateral Scler2012; 13(5): 459–464.
22.
LublinFDReingoldSCCohenJA, et al. Defining the clinical course of multiple sclerosis: The 2013 revisions. Neurology2014; 83(3): 278–286.
23.
MackayME.Solar energy an introduction. 1st ed. Oxford: Oxford University Press, 2015.
24.
IDEAM. Atlas de radiación solar, ultravioleta y ozono de Colombia—Instituto DE Hidrología Meteorología Y Estudios Ambientales de Colombia, http://atlas.ideam.gov.co/presentacion/ (accessed 10 July 2022).
25.
RogersonPA.A generalization of Hewitt’s test for seasonality. Int J Epidemiol1996; 25(3): 644–648.
26.
RauR.NPST: A generalized non-parametric seasonality test. In: European population conference: Population challenges in ageing societies, Liverpool, UK, 2006, https://epc2006.eaps.nl/papers/60475
27.
WakefieldJSalwayR.A statistical framework for ecological and aggregate studies. J R Stat Soc Ser A2001; 164(1): 119–137.
28.
HedströmAKHillertJBrennerN, et al. DRB1–environment interactions in multiple sclerosis etiology: Results from two Swedish case–control studies. J Neurol Neurosurg Psychiat2021; 92(7): 717–722.
29.
AlcinaAAbad-Grau MdelMFedetzM, et al. Multiple sclerosis risk variant HLA-DRB1*1501 associates with high expression of DRB1 gene in different human populations. PLoS ONE2012; 7(1): e29819.
30.
ToroJCuellar-GiraldoDDíaz-CruzC, et al. HLA-DRB1*14 is a protective allele for multiple sclerosis in an admixed Colombian population. Neurol Neuroimmunol Neuroinflamm2016; 3(1): e192.
31.
WatadAAzrielantSBragazziNL, et al. Seasonality and autoimmune diseases: the contribution of the four seasons to the mosaic of autoimmunity. J Autoimmun2017; 82: 13–30.
32.
HirveSNewmanLPPagetJ, et al. Influenza seasonality in the tropics and subtropics—when to vaccinate. PLoS ONE2016; 11(4): e0153003.
33.
Porras-RamírezARico MendozaAMoreno-MontoyaJ, et al. Mortalidad asociada con las temporadas de mayor circulación de los virus de la influenza en Bogotá, Colombia, 1997–2005. Rev Panam Salud Publica2009; 26(5): 435–439.
34.
RemolinaYAUlloaMMVargasH, et al. Viral infection in adults with severe acute respiratory infection in Colombia Schildgen O, ed. PLoS ONE2015; 10(11): e0143152.
