Environmental, Lifestyle, and Medical Risk Factors Associated With Multiple Sclerosis: A Case-Control Study in Kermanshah, Iran

Background and Objectives: Multiple sclerosis (MS) is a chronic immune-mediated disorder of the central nervous system with increasing prevalence in Iran. Identifying modifiable environmental and lifestyle risk factors is essential for disease prevention and public health strategies. Therefore, this study aimed to evaluate environmental, lifestyle, and medical factors associated with multiple sclerosis in Kermanshah, Iran. Methods: This case-control study was conducted on 300 MS patients and 300 matched healthy controls. Data on demographics, substance use, sun exposure, medical and psychiatric history, family history, and major life stressors were collected using questionnaires. Univariate and multivariable logistic regression analyses were utilized to estimate crude and adjusted odds ratios and 95% confidence intervals. Results: MS patients were more likely to be female, with lower educational attainment compared to controls. In addition, reduced sun exposure in adolescence and adulthood was strongly associated with MS (P<0.05). Moreover, passive smoking during adolescence and maternal smoking during pregnancy were related to higher odds of MS (aOR 1.54, 95% CI: 1.05–2.72 and aOR 3.70, 95% CI: 1.19–11.52, respectively). A history of depression (aOR 3.17, 95% CI: 1.95–5.13) and migraine (aOR 1.94, 95% CI: 1.14–3.30) were also significantly associated with MS. Additionally, a family history of MS in first-degree relatives was more frequent among cases (aOR 2.31, 95% CI: 1.36–3.94). All models were adjusted for gender, ethnicity, and education level. Conclusion: The findings indicated that MS in Kermanshah is shaped by reduced sunlight exposure, passive and maternal smoking, psychiatric comorbidities, and family history, highlighting several modifiable environmental determinants that may guide targeted prevention efforts and inform public health strategies in high-prevalence regions.