Antibiotic use in midlife associated with memory and thinking decline in women

A scientist analysing research results on a screen

By Quang Tran | Wednesday 23 March 2022

Researchers in the US have found that chronic antibiotic use in women during middle age is linked with poorer cognition even seven years later. The scientific journal PLOS One, published the results today (Wednesday 23 March).

What did the scientists do?

The researchers looked at 14,542 volunteer female nurses living in the US. Nurses completed a self-administered computerised test to measure aspects of their memory and thinking.

What did researchers find?

They found that women exposed to antibiotics for two months in midlife had poorer memory and thinking, up to seven years later.

Scientists still saw this, when they considered other potential factors that could have influenced this relationship, including the presence of other health conditions.

The change in memory and thinking through antibiotic use was roughly equivalent to three to four years of aging.

What did our expert say?

Dr Susan Kohlhaas, Director of Research from Alzheimer’s Research UK, said:
“Our brains don’t exist in isolation from the rest of the body, but are connected in a variety of ways. Antibiotics are commonly prescribed for numerous treatable conditions and have revolutionised healthcare; however, little has been done to investigate their long-term effects on memory and thinking.

“Researchers found the changes in memory and thinking in this group of women were small and results do not suggest people who take antibiotics in midlife are any more likely to develop dementia. However, this research does suggest that it’s important to consider the longer-term outcomes of medication on memory and thinking.

“We can’t be sure of cause and effect in this sort of observational study and the authors highlight that these findings present a direction for future research, rather than being conclusive evidence of a link between antibiotics and memory and thinking skills.

“This study did not look at the direct impact antibiotics had on the gut bacteria, and while researchers have linked the makeup of the intestinal microbiome to brain health, this was not investigated directly in this study. The relationship identified in this research could be a result of the infections that antibiotics were used to treat, rather than the drugs themselves. It is important to properly manage treatable health conditions and people who have concerns about any aspect of their health should speak to their GP.

“Midlife is increasingly being seen as a time to act, and there are things we can do to reduce our risk of dementia. This includes not smoking, only drinking in moderation, staying mentally and physically active, eating a balanced diet, and keeping cholesterol and blood pressure levels in check can all help to keep our brains healthy as we age. Find information and advice on brain health at

Read the full study ‘Association of midlife antibiotic use with subsequent cognitive function in women’ in PLOS One.

About the author

Quang Tran