WEDNESDAY, July 12, 2017 (HealthDay News) -- Women with a longer history of breast-feeding may be less likely to develop multiple sclerosis than mothers who skip breast-feeding or nurse for briefer periods, a new study suggests.
Researchers compared nearly 400 women with MS or its precursor, known as clinically isolated syndrome (CIS), with a similar healthy group. They found that mothers who had breast-fed one or more children for a total of 15 months or longer were 53 percent less likely to develop MS or CIS than those with zero to four months of total breast-feeding.
"No one has shown before that breast-feeding could have a prolonged benefit on the mother's immune system," said study author Dr. Annette Langer-Gould. She's a research scientist in neurology at Kaiser Permanente in Pasadena, Calif.
"This is one more piece of evidence that women who want to breast-feed should be supported to do so," Langer-Gould added. "It's not just good for the baby, but may have prolonged maternal health benefits."
An estimated 400,000 Americans -- and 2.5 million people worldwide -- have MS, according to the Multiple Sclerosis Foundation. It's an incurable autoimmune disease, meaning the body attacks its own tissues, often causing numbness, tingling, bowel and bladder difficulties, walking problems and thinking issues. MS disproportionately affects women of childbearing age compared to men or older women.
Existing research has revealed a bevy of other health benefits related to breast-feeding, including lower risks of type 2 diabetes, breast and ovarian cancers, and heart attack. These benefits appear to increase for women who breast-feed longer.
In the new study, Langer-Gould and her team analyzed 397 women (average age 37) who were newly diagnosed with MS or CIS, a first episode of symptoms that may or may not progress to MS. This group was compared to 433 healthy women matched for age and race, all of whom completed questionnaires focusing on their pregnancies, breast-feeding, hormonal contraceptive use and related factors.
Eighty-five of the healthy women had breast-fed for 15 months or more, compared to 44 of those with MS. Among the healthy women, 110 had breast-fed for zero to four months, compared to 118 of those with MS.
Langer-Gould had initially thought lack of ovulation might play a role in MS risk. But the results showed that the total number of years a woman ovulated was not linked to MS risk. Neither were other related factors, such as number of pregnancies or hormonal contraceptive use.
Rather, Langer-Gould believes that prolonged breast-feeding suppresses pro-inflammatory cells that may contribute to the development of MS.
"It's entirely speculative, because, again, no one's really studied this," she said. The new research doesn't prove a cause-and-effect relationship between breast-feeding and lower MS risk, only that an association exists.
Nicholas LaRocca is vice president of health care delivery and policy research for the National Multiple Sclerosis Society. He called the new research "another piece of the puzzle" since prior research had established relationships between MS risk and biological events surrounding pregnancy and childbirth.
"I think what we've been learning in recent years is that the immune system, which we knew was complicated, is more complicated than we thought and has a number of other relationships with other parts and aspects of the body," LaRocca said.
Langer-Gould and LaRocca agreed that further research is necessary to better define the biological factors at play between breast-feeding and MS risk.
"I think where you go from here is to see if these results can be replicated, but also to try to fit this in with everything else we know about the risk of MS," LaRocca said.
"And of course this is a modifiable risk factor, so it provides another reason women should consider breast-feeding," he added. "It does seem to have a number of positive benefits -- particularly for someone who might be at greater risk to begin with, such as a family history of MS."
Langer-Gould said further investigation of the link between breast-feeding and MS risk might potentially offer clues about the development of MS in general, regardless of gender, age or childbearing status.
"There's always the potential that you'd stumble on a new biomarker or pathway," she said.
The study was published online July 12 in the journal Neurology.
SOURCES: Annette Langer-Gould, M.D., Ph.D., research scientist, neurology, Kaiser Permanente, Pasadena, Calif.; Nicholas LaRocca, Ph.D., vice president, health care delivery and policy research, National Multiple Sclerosis Society, New York City; July 12, 2017, online issue, Neurology