WEDNESDAY, Dec. 11, 2024 (HealthDay News) -- For children genetically predisposed to develop multiple sclerosis (MS), exposure to cigarette smoke in the family home could raise that risk even higher, new research shows.

"A higher genetic MS risk is associated with an increased vulnerability to the negative effects of household smoking on brain development," conclude a Dutch team led by Dr. Rinze Frederik Neuteboom of Erasmus Medical Center in Rotterdam.

The new study also probes the roots of MS, suggesting that even though most people develop the autoimmune illness between their 20s and 40s, it might originate as far back as childhood.

MS occurs when the body's immune system goes awry, attacking the myelin sheath that protects nerves. Over time, this can lead to a debilitating loss of movement, balance, cognitive abilities and other symptoms.

In the new study, Neuteboom and colleagues looked at data from a large database tracking the health of Dutch children.

Among other factors, data was collected on known environmental risk factors for MS, such as infection with the Epstein Barr virus, blood levels of vitamin D, parents' smoking, childhood weight and levels of outdoor activity at the age of 5.

Scans were also taken of the brains of more than 5,000 of the children between the ages of 9 and 13, looking at brain volume and the "microstructures" of the brain.

Genetic data was also collected for more than 2,800 children.

The research showed that 642 children tested positive for Epstein Barr virus infection and 405 had been exposed to household parental smoking.

The main finding: There was a relationship between a child's genetic predisposition to MS, their exposure to a parents' smoking, and brain changes seen on the scans.

Specifically, kids whose genes already put them at higher risk of developing MS later in life, and who were also exposed to secondhand smoke at home, tended to have lower brain volumes and lower "gray matter" volume in their brains, Neuteboom's team reported.

The exact route by which genes and smoke exposures combine to up brain risks aren't known, the researchers said.

However, they theorize that a child's genes may make their immune system particularly vulnerable to the Epstein-Barr virus, which in recent years has been suggested as a possible trigger for MS.

Tobacco smoke may also exacerbate inflammation and immune system dysfunction, further heightening the risk.

"The increased brain vulnerability to the effects of parental smoking may increase exposure of [central nervous system] antigens to the developing immune system, increasing the risk of a brain specific autoimmune disease" such as MS, the study authors wrote.

The findings give parents yet another reason to consider quitting smoking, at least around their kids, as a means of preventing illnesses such as MS, Neuteboom and his colleagues wrote.

They published their findings Dec. 10 in the Journal of Neurology Neurosurgery & Psychiatry.

More information

Find out more about the causes and treatments of multiple sclerosis at the National MS Society.

SOURCE: Journal of Neurology Neurosurgery & Psychiatry, news release, Dec. 10. 2024