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Updated: May 26, 2026
A Method of Trigonometric Modelling of Seasonal Variation Demonstrated with Multiple Sclerosis Relapse Data
Published on: December 9, 2015
Multiple sclerosis: long time modifications of seasonal differences in the frequency of clinical attacks
1Dipartimento Neuroscienze, Azienda Ospedaliera Universitaria Ospedali Riuniti di Salerno U.O.S.D. Malattie Demielinizzanti, Via s. Leonardo, 84100 Salerno, Italy. geriul@tin.it
Abstract:
Previous papers show different patterns of seasonal distribution of multiple sclerosis attacks. This paper compares long-time modifications. Salerno MS registry (Southern Italy), was reviewed, including 189 patients, age onset 12-51 years (mean = 29.88, SD = 8.4), disease duration mean = 6.94 years (1-29), attacks mean = 4.5 (2-25, SD = 3.41). Data were stratified by decades. Number of events/month was analyzed by odds ratios and forecast modeling (ARIMA); means by ANOVA and post hoc tests, and correlations by multiple regression. We found 869 relapses: J = 72, F = 48, M = 122, A = 75, M = 68, Jn = 59, Jl = 81, A = 74, S = 63, O = 70, N = 72, D = 65. In 2001-2008 there was one significant peak (March); in 1991-2000 many (greatest = July), and in 1984-1990, one positive (June), one negative (April). Differences between 1990s and 2000s are significant. It is the first study addressing ultradecennal trends, and finding that the season distribution of MS attacks is significantly different: the study confirms frequency peaks in early spring and summer, but they are different in different decades. This significant ultra-decade difference might support hypotheses more linked to infections or toxic substances than to sunlight, UV, or similar.
Insights
Seasonal patterns of multiple sclerosis (MS) attacks are shifting over time. This study reveals significant ultra-decadal changes in MS relapse seasonality, suggesting environmental factors beyond sunlight may be involved.
Area of Science:
- Neurology
- Epidemiology
- Environmental Health
Background:
- Previous research indicates varying seasonal distributions for multiple sclerosis (MS) attacks.
- Understanding long-term trends in MS relapse seasonality is crucial for identifying potential triggers.
Purpose of the Study:
- To analyze long-term modifications in the seasonal distribution of multiple sclerosis attacks.
- To investigate ultra-decadal trends in MS relapse patterns.
Main Methods:
- Review of the Salerno MS registry (Southern Italy) data from 1984-2008, including 189 patients.
- Statistical analysis of 869 relapses using odds ratios, ARIMA forecast modeling, ANOVA, post hoc tests, and multiple regression, stratified by decades.
- Comparison of seasonal attack patterns across three decades (1984-1990, 1991-2000, 2001-2008).
Main Results:
- Significant differences in seasonal MS attack distribution were observed between the 1990s and 2000s.
- While early spring and summer peaks were confirmed, their timing and intensity varied significantly across decades.
- Specific patterns included a single March peak (2001-2008), multiple peaks with a July maximum (1991-2000), and June/April peaks (1984-1990).
Conclusions:
- The seasonal distribution of multiple sclerosis attacks is not static and shows significant ultra-decadal changes.
- These evolving patterns may implicate factors like infections or toxic substances more than solely sunlight or UV exposure.
- This research highlights the dynamic nature of MS seasonality and the need for further investigation into environmental influences.
