If you're a senior, here's one less thing to worry about when it comes to your health: If you're taking antibiotics, they won't increase your risk of cognitive decline or dementia, a recent study found.

Why would there be a connection between taking antibiotics and our brain's health in the first place? In addition to helping our bodies fight bacterial infections, antibiotics can disrupt the community of tiny organisms that live in our intestines and support digestion — the gut microbiome, study author, Andrew T. Chan of Harvard Medical School explained.

“Given that older adults are more frequently prescribed antibiotics and are also at higher risk for cognitive decline, these findings offer reassurance about using these medications.”

“Because the gut microbiome has been found to be important for maintaining overall health, and possibly cognitive function, there was concern that antibiotics may have a harmful long-term effect on the brain,” he continued. “Given that older adults are more frequently prescribed antibiotics and are also at higher risk for cognitive decline, these findings offer reassurance about using these medications.”

Over 13,550 healthy participants who were all over 70 took part in the Harvard Medical School study. “Healthy” was defined as not having heart disease, dementia or serious physical disabilities that might shorten life to less than five years. At the start of the study, and during the following two years, all the participants were free of cognitive impairment and dementia.

Looking over participants' prescription records during this period, the researchers determined their antibiotic use. Sixty-three percent of the volunteers used antibiotics at least once.

Next, participants were divided into two groups: 1) those who used antibiotics and 2) those who never used antibiotics. To calculate whether the amount of antibiotics increased their risk, the research team also reviewed how many prescriptions they had in the first two years — from zero to five or more.

The team then followed the participants for the next five years on average. They gave the volunteers a series of cognitive tests at the start of the study, after one year's time, and then every two years thereafter. The tests measured thinking and memory skills that included attention, executive function and language.

The criteria for cognitive decline encompasses a gradual loss or reduction in thinking abilities including memory, judgment, thinking and reasoning. When these problems become more advanced and affect the ability to effectively manage daily tasks, it's diagnosed as dementia.

At the study's end, the researchers considered the cognitive scores and compared people who took antibiotics to those who did not. What did they find?

There was no difference between the groups.

Even after the researchers adjusted for other factors such as family history of dementia, cognitive function at the start of the study and other medications known to affect cognition, they still found that antibiotic use did not increase the risk for cognitive impairments or dementia.

One shortcoming of the study was that it only followed the participants for a relatively short period of time, so there was no way to determine if there were long term effects of antibiotic use.

Whether or not you've been prescribed antibiotics, it's a good idea to do what you can to keep your brain healthy. Alzheimers.gov is a national website offering information on Alzheimer's disease. It recommends the following ways to help to reduce your risk of cognitive decline.

The study is published in Neurology.