Researchers have linked an increased risk of developing multiple sclerosis (MS) to exposure to paints and solvents in people who carry small variations in some genes that also make them susceptible to MS, compared with people that don’t have those genetic variants. Reporting in the journal Neurology, the work showed that the exposure increased the risk of MS by fifty percent. That made those individuals with the risk variants and experience with paints or solvents seven times more likely to get the disease as people who did not carry those variants and had not been around paints.
The researchers also found another factor. When people had been exposed to solvents or paints, carried the MS risk variants and were also smokers, they became thirty times more likely to get MS compared to those without those characteristics.
"These are significant interactions where the factors have a much greater effect in combination than they do on their own," said study author Anna Hedström, MD, Ph.D., of the Karolinska Institutet in Stockholm, Sweden. "More research is needed to understand how these factors interact to create this risk. It's possible that exposure to solvents and smoking may both involve lung inflammation and irritation that leads to an immune reaction in the lungs."
The study involved 2,042 people who had recently gotten MS diagnoses in Sweden, as well as 2,947 people that were matched to the participants for sex and age. Blood samples were taken, and the researchers looked for two variants in human leukocyte antigen genes. One of those variants increases a person’s risk for developing MS, while the other one reduces that risk. One caveat of the study - the scientists relied on the participant’s recollection about whether or not they had been around organic solvents, paint materials or varnish, and if they smoked or not.
Of those individuals that had no MS risk variants, had not been around solvents and did not smoke, 139 people had MS and 525 did not. Of the people that carried the MS risk variants, had been exposed to paints or solvents, but did not smoke, 34 people had MS while 19 did not. In the group of smokers that also carried genetic risk variants, and were exposed to solvents, 40 individuals had MS and five people did not. While the group sizes got smaller, the proportion of people with the disease rose sharply. The combined factors of solvents, smoking and risk variants were calculated to increase the risk of getting MS by a whopping 60 percent.
"How this cocktail of MS genes, organic solvents and smoking contributes so significantly to MS risk warrants investigation," commented Gabriele C. DeLuca, MD, DPhil, of the University of Oxford in the United Kingdom and a member of the American Academy of Neurology. "In the meantime, avoiding cigarette smoke and unnecessary exposure to organic solvents, particularly in combination with each other, would seem reasonable lifestyle changes people can take to reduce the risk of MS, especially in people with a family history of the disease."