Do Environmental Factors Prompt MS?

A biomarker of Epstein-Barr virus, infectious mononucleosis, and smoking are environmental factors associated with multiple sclerosis (MS) that have the strongest consistent evidence, according to an umbrella review of 44 meta-analyses.

The review included 416 primary studies of different risk factors and MS, including vaccinations, comorbidities, surgeries, environmental agents, and biomarkers. Of those, only 3 had strong enough sample sizes to make consistent associations:

• IgG seropositivity for Epstein-Barr virus nuclear antigen (EBNA) (odds ratio [OR], 4.46)

• infectious mononucleosis (OR, 2.17)

• smoking (OR, 1.52)

The study authors conclude that more data from better-designed studies are needed to establish robust associations.

Citation: Belbasis L, Bellou V, Evangelou E, Ioannidis JP, Tzoulaki I. Environmental risk factors and multiple sclerosis: an umbrella review of systematic reviews and meta-analyses. Lancet Neurol. 2015;14(3):263-273. doi: 10.1016/S1474-4422(14)70267-4.