This Common Medication Could Be Hurting Your Brain, New Study Says

Women who took this on a regular basis showed more rapid signs of cognitive decline.

Many of us think a decrease in cognitive ability is part of the natural aging process—the so-called "senior moments" that happen more frequently as we get older. Forgetting to do something or having small details slip your mind might not seem like a serious issue, but these brain blips may be a sign of mild cognitive impairment (MCI), which can lead to dementia down the line. According to the Mayo Clinic, things like avoiding excessive alcohol use, limiting exposure to air pollution, exercising regularly, and getting good sleep at night can help keep our brains healthy—but a recent study found that a common medication could be thwarting those efforts. Women who took certain prescription pharmaceuticals were more likely to have decreased cognitive ability over time. Read on to learn which medication could be hurting your brain if you take it too often.

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Chronic antibiotic use was linked to a decrease in cognitive ability in women.

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A study published in PLOS ONE last month found that women who frequently took antibiotics during midlife showed faster rates of cognitive decline than those who did not.

While antibiotics are prescribed to fight infections caused by bacteria, such as urinary tract infections (UTI) or strep throat, they are not effective in treating illnesses that result from viruses, such as cold and flu. Taking antibiotics unnecessarily contributes to antibiotic resistance, according to the Centers for Disease Control and Prevention (CDC). And while antibiotic resistance is a pressing issue in itself, this new research raises another area of concern.

"Ongoing antibiotic use is harmful in many ways to our health," Sherry Ross, MD, specialist in obstetrics and gynecology at Providence Saint John's Health Center in Santa Monica, California, told Medical News Today. "This study showed yet another association of how chronic antibiotic use…may have an association with a decline in cognitive abilities."

Researchers asked women about their antibiotic use and had them complete cognitive testing.

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Researchers analyzed responses from 14,542 women who completed the 2009 Nurses' Health Study II questionnaire. The study participants, who had an average age of 55, were asked how often they took antibiotics, and for how long. Those who reported at least two months of antibiotic exposure over the course of the previous four years had lower cognitive scores on the the CogState, a self-administered, online cognitive test that participants took between 2014 and 2018.

Some lessening of brainpower is normal as we age, and researchers factored this into the study. While participants' scores dropped each year, women who regularly took antibiotics showed a greater amount of cognitive decline than those who did not: Where the study's authors would have expected to see one year's worth of decline, the antibiotic-takers showed three to four years' worth of deterioration.

This decline could be due to the "gut-brain axis."

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The gut microbiome, which is filled with bacteria, viruses, and fungi, is located in your large intestine and is involved with your immune system. Researchers think that the gut-brain axis, or the communication between your central nervous system and your gut microbiome, actually allows this bacteria to affect the brain. According to Medical News Today, some evidence even suggests changes in your gut could lead to depression, anxiety, schizophrenia, and Alzheimer's disease.

Currently, there is limited research on the effect of antibiotic use on cognition. However, as antibiotics are designed to kill bacteria, this, in turn, affects the gut microbiome. Given what scientists understand about this two-way communication via the gut-brain axis, researchers from the present study suggest it "could be a possible mechanism for linking antibiotics to cognitive function."

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Researchers are still studying all the factors that play into cognitive decline.

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While there was a significant association between increasing antibiotic use in midlife and poorer cognitive scores, there are other unidentified factors that may contribute to a decline in cognitive ability. "We cannot rule out the possibility that some other risk factor associated with the use of antibiotics in midlife is the cause of the mild declines in cognitive function," co-senior author of the study, Andrew T. Chan, MD, MPH, professor of medicine at Harvard Medical School, told Medical News Today.

The study cohort was large, but results were confined to women. Future research will need to examine chronic antibiotic use in men, as well as in patients of different races and ethnicities, researchers noted.

"Our study opens new avenues of research into possible ways of modifying the gut microbiome to prevent cognitive decline with aging," said Chan, who is also chief of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital. "This also underscores the importance of judicious use of antibiotics across the life course to minimize potential long-term consequences of altering the gut microbiome."

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