long-term use of antibiotics could disrupt brain function

Treatments involving long-term use of antibiotics have the potential to disrupt brain functions, suggests a new research which found that healthy gut bacteria is crucial to keeping the mind sharp.

A special kind of immune cell serves as an intermediary between gut bacteria and the brain, showed the findings that could also help to alleviate the symptoms of mental disorders.

The gut and the brain "talk" to one another via hormones, metabolic products or direct neural connections. 

In this study, the researchers switched off the gut microbiome in mice, that is their intestinal bacteria, with a strong concoction of antibiotics. 

Compared to the mice that had not undergone treatment, they subsequently observed significantly fewer newly formed nerve cells in the hippocampus region of the brain. 

The memory of the treated mice also deteriorated because the formation of these new brain cells - a process known as neurogenesis - is important for certain memory functions.

As well as impaired neurogenesis, the researchers also found that the population of a specific immune cell in the brain - the ly6C(hi) monocytes - decreased significantly when the microbiota was switched off. 

Applied to humans, the findings do not show that all antibiotics disrupt brain function, as the combination of drugs used in the study was extremely potent.

"It is possible, however, that similar effects could result from treatments involving long-term use of antibiotics," said one of the researchers Susanne Wolf from Max Delbruck Centre for Molecular Medicine in the Helmholtz Association, Berlin, Germany.

The findings were published in the journal Cell Reports. 

The research team also found that the antibiotics may affect neurogenesis directly, and not act only via the gut bacteria.

The new study is also of significance for treating people with mental disorders such as schizophrenia or depression, who also have impaired neurogenesis, Wolf said.

"In addition to medication and physical exercise, these patients could potentially also benefit from probiotic preparations,” Wolf noted.