Head trauma raises MS risk if combined with certain genetic makeup

Head trauma combined with a certain type of genetic makeup might increase the risk of multiple sclerosis (MS) by almost 18 times versus people without head trauma and the genetic makeup, a new study has found.

The study was titled ‘Head trauma results in manyfold increased risk of multiple sclerosis in genetically susceptible individuals,’ and was published in the Journal of Neurology, Neurosurgery, and Psychiatry.

There are thought to be a number of environmental triggers for MS. There is growing evidence that any injury that causes damage to the scalp, skull, or brain may increase the risk of developing the condition. “Recent large register-based studies have reported an increased risk of MS following traumatic brain injury, particularly if repeated and requiring longer hospital care,” the researchers wrote, noting that head trauma may cause the brain to become inflamed.

The researchers focused on genetic makeup, in particular the human leukocyte antigen (HLA) family of genes. These assist the immune system in discerning foreign matter from healthy tissue. The DRB1*15:01 allele is linked to a higher risk of developing MS, whereas the HLA-A*02:01 allele appears to protect against MS. An allele is a variant form of a gene that arises through mutation or genetic recombination.

By collecting data from people in Sweden about demographic factors, environmental exposures, and lifestyle habits from April 2005 to April 2015.

Having head trauma increased the risk of developing MS by 30%. For those who reported head trauma in the previous five years, the risk was 60% higher compared with not having head trauma.

Blood samples were available from 2,057 people with MS and 2,887 controls. Genetic testing revealed 1,122 (54.5%) people with MS and 801 (27.7%) controls carried the DRB1*15:01 allele. The proportion of those without the protective HLA-A*02:01 allele was 58.6% and 45.9%, respectively.

Compared with people without these two genetic factors who’d never had head trauma, the risk of developing MS was increased by 18 times among those with both genetic factors who had experienced head trauma within five years before the onset of disease.

“Our study could prompt further research to uncover the underlying mechanisms linking head trauma, genetic factors and MS development,” wrote the researchers, who said for policymakers and doctors, it “may also contribute to policy discussions regarding preventive measures and risk assessment strategies.”