August 23, 2021 – Did your parents enlighten themselves as a child? If so, you may have a higher risk of developing rheumatoid arthritis as an adult, a new study suggests. The researchers found evidence that women whose parents smoked were 75% more likely to develop the disorder.
In people with rheumatoid arthritis (RA), the immune system attacks and damages the joints and causes pain. The disease is fairly rare, affecting 1% or less of people, and most don’t develop it regardless of whether their parents smoked. However, experts say the study is important because it provides more evidence on how dealing with secondhand smoke in childhood can have a lifelong impact on the immune system.
“The results show the importance of reducing exposure to cigarette smoke to reduce the risk of disease,” said Milena A. Gianfrancesco, PhD, epidemiologist at the University of California, San Francisco. “They underline the need to concentrate not only on personal smoking habits, but also on other sources of passive smoke exposure.”
The researchers, whose study appeared in the journal Arthritis & Rheumatology on Aug. 18, tracked more than 90,000 women who took part in the Nurses’ Health Study II between the ages of 25 and 42 in 1989, the participants were 35 and 93% were white . Almost two thirds had never smoked themselves and 65% said that their parents smoked in their childhood.
The researchers found that about 350 of the women developed RA over the next 3 decades. The researchers then tried to find out whether these women were more likely to have had smoking parents.
The study authors estimated that childhood smoking exposure of parents increased their risk of RA by 41%. The researchers also tried a different statistical strategy that aimed to take into account the fact that many children whose parents smoke smoke themselves. This analysis suggested that smoking parents could increase the risk of RA by 75%.
So does that mean women whose parents smoked are doomed to develop arthritis? Not at all. The overall rate of RA in the women in the study was about half of 1%, says Kazuki Yoshida, MD, lead study author and epidemiologist at Brigham and Women’s Hospital. And most of these women had parents who smoked as children.
Why might secondhand smoke increase the risk of RA?
Secondhand smoke can irritate the lungs and lead to the formation of abnormal proteins, says Yoshida. “The immune system makes antibodies to attack such abnormal proteins. This immune reaction can spread to other parts of the body and attack normal tissue including the joints. “
In addition, “smoking increases the risk of infection, which in turn could increase the risk of RA,” says Gianfrancesco, who wrote a comment on the study. “Smoking is also known to cause genome changes that can trigger RA in susceptible people.”
Other studies have linked smoking exposure to autoimmune diseases. Earlier this year, researchers who followed nearly 80,000 French women reported that they found an association between childhood or adult smoke exposure and higher rates of RA.
The new study has limits. It says nothing about whether men are at a similar risk. And the nurses are overwhelmingly white, which means the results may not apply to women of other races.
Still, Gianfrancesco praised the study, saying it relied on extensive data and strong statistical methods.
How can the findings be useful? According to Gianfrancesco, it’s important to understand that children with a family history of RA or other autoimmune diseases are particularly vulnerable to the effects of secondhand smoke, as they may already be more prone to developing the diseases.
“Parents should keep their children away from secondhand smoke at home or in other smoke-prevalent environments, such as in the office.
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Arthritis & Rheumatology: “Passive smoking throughout the life course and the risk of developing rheumatoid arthritis in adulthood in women”, “Where there is smoke, there is a joint: Passive smoking and rheumatoid arthritis.”
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