Antibiotics can help you when you’re sick, but a new study finds taking them during middle age could be harmful for your brain. Researchers found evidence that women using antibiotics for at least two months in their mid-50s were more likely to suffer from cognitive decline years later. They believe that gut microbiome could be a driving factor.
A team from Harvard Medical School and Rush Medical College collaborated to find a potential relationship between midlife antibiotic use and brain health. They used data from participants in the ongoing Nurses’ Health Study II that enrolled female nurses from age 25 to 42 since 1989. Every two years, participants in the study filled out a questionnaire regarding their lifestyle, medication usage, and health-related issues.
In 2009, the average age of participants was around 57 years-old. The questionnaire asked each woman to report on their total antibiotic use over the past four years and the reasons why they needed to take those drugs.
Seven years after the women first took those antibiotics, the researchers conducted an online cognitive test to measure their psychomotor function, information processing speed, vigilance and visual attention, visual learning, short-term memory, attention, and working memory.
Of the 14,542 women who completed the cognitive test, those using antibiotics for at least two months did slightly worse overall. Specifically, their scores dropped in psychomotor speed, attention, and learning and working memory. The cognitive results also appeared worse for every additional year that passed since their initial antibiotic usage.
“Thus the relation of antibiotic use to cognition was roughly equivalent to that found for three to four years of aging,” the study authors write in the journal PLOS One.
Another link to the ‘gut-brain axis’
Study authors suspect that the gut-brain axis may be responsible for this link between antibiotics and cognitive decline. Studies show that antibiotics have a significant impact on a patient’s gut makeup. These drugs can alter gut microbiota for years.
Since both human and animal studies show that changes in the gut microbiome may have a connection to various brain diseases, thanks to the gut-brain axis, the team concludes that there could be a link to failing cognitive skills as well.
“These data provide a better understanding of potential complications of antibiotics throughout life, as well as generate hypotheses about the role of the gut microbiome in cognition,” the study authors write.
It seems to me there is a lurking variable here which should be considered. Was the cognitive decline due to the antibiotic use or due to the illness that the antibiotic was treating? For example, it is known that Covid-19 causes adverse cognitive effects, even without antibiotic use.