A new study published in PLOS One has found that chronic antibiotic use in middle age is connected to cognitive decline in women.
According to the NHS, antibiotics are used to treat or prevent some types of bacterial infection. They work by killing bacteria or preventing them from spreading.
The effect of antibiotics on the brain
Few studies have investigated the cognitive impact of chronic antibiotic use in people in middle age without dementia.
Doctor 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 from Massachusetts General Hospital, Harvard Medical School, and Rush University Medical Center decided to investigate. They investigated the impact of chronic antibiotic use in middle age on cognitive function.
The researchers found that women who took antibiotics for two months during middle age had poorer memory and thinking, up to seven years later.
They analysed a questionnaire completed by 14,542 volunteer female nurses living in the US. The questionnaire contained information about their antibiotic use, and measured aspects of their memory and thinking.
The findings remained consistent even after taking into account other potential factors that could have influenced this relationship, including the presence of other health conditions.
The change in memory and thinking due to antibiotic use was roughly equivalent to three to four years of ageing.
The gut-brain axis
The study did not investigate the direct effect antibiotics had on the gut bacteria. However, as reported by Medical News Today, antibiotic use can alter the gut microbiome because, by their very nature, they kill bacteria. These changes can last for months or years after exposure.
There is two-way communication between the gut and the central nervous system, which is called the gut-brain axis. Scientists think this axis enables our gut bacteria to influence the brain.
The gut microbiomeregulates brain development and function throughout life. Separate research has found some evidence that changes to the gut microbiome could have a role in developing psychiatric and neurologic conditions, such as anxiety, depression, autism spectrum disorder, schizophrenia, and Alzheimer’s disease.
Doctor Sherry Ross, a specialist in obstetrics and gynaecology at Providence Saint John’s Health Center, told Medical News Today:
Ongoing antibiotic use is harmful in many ways to our health. […] This study showed yet another association of how chronic antibiotic use […] may have an association with a decline in cognitive abilities.