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July 2, 2024 — Exposure to maternal smoking during pregnancy and parental smoking during early childhood may increase the risk of developing multiple sclerosis (MS) later in life, according to new research presented at the Congress of the European Academy of Neurology 2024.
The study, part of the Environmental Risk Factors In Multiple Sclerosis (EnvIMS) project, is a large-scale, multinational, case-control study exploring how environmental factors influence MS risk. The findings underscore the significance of early-life factors in the development of MS, an area that is increasingly gaining attention in medical research.
Investigating Early-Life Exposure
“Early-life factors are crucial in determining the risk for MS, and this is an emerging field of research,” said Dr. Caterina Ferri, the lead investigator and a neurologist at the University Hospital of Ferrara, Italy. She highlighted that while the link between active smoking and MS is well-documented, the impact of parental smoking on the risk of MS in children has been less clear.
The EnvIMS study analyzed data from more than 6,000 individuals across Canada, Italy, and Norway. Over 2,000 MS cases diagnosed at age 18 or older were compared to more than 4,000 control subjects matched by sex, age, and geographical area. The participants completed the EnvIMS-Q questionnaire, which gathered detailed information on parental smoking history, including maternal smoking during pregnancy and both maternal and paternal smoking during childhood.
Key Findings and Regional Discrepancies
The study revealed significant geographical variations in the association between parental smoking and MS. Notably, the strongest association was observed in Norway, where maternal smoking during pregnancy was significantly linked to an increased risk of MS in offspring (odds ratio [OR], 1.38; P = .003). This association remained significant among males even after adjusting for confounding factors (adjusted OR, 1.7; P = .017).
Conversely, no significant association was found in the Italian and Canadian populations. Dr. Ferri noted that the Italian cohort from Sardinia has a high familial risk for MS, which may have influenced the findings.
While paternal smoking showed a tendency to be associated with MS in the Canadian population (OR, 1.27; P = .024), this significance disappeared after statistical adjustments.
Complex Interplay of Factors
The study also highlighted the complexity of MS as a multifactorial disease, influenced by a combination of genetic and environmental risk factors. Dr. Ferri pointed out that the timing of exposure to these factors, particularly during the early stages of life when the immune system is still developing, plays a crucial role in determining MS risk.
“In addition to smoking, factors such as breastfeeding and infections like mononucleosis can have significant impacts. During early childhood, certain infections may even be protective, while they can become risk factors later in life,” she explained.
Future Directions and Implications
Despite the robust findings, Dr. Ferri emphasized that there is no definitive answer regarding the specific causes of the observed associations. The study raises questions about whether the chemicals in tobacco smoke, epigenetic modifications, or a complex interplay of both are responsible.
The EnvIMS study, funded by MS foundations and health institutions in Italy, Norway, and Canada, continues to explore these complex interactions. The research aims to provide a clearer understanding of how environmental exposures in early life can influence the risk of developing MS, ultimately informing better prevention strategies.
Dr. Ferri reported no relevant conflicts of interest, underscoring the study’s commitment to unbiased scientific inquiry.
Contact Information: For further details, contact Dr. Caterina Ferri at the University Hospital of Ferrara, Italy.
