It's Not All in the Head: Is the Key to Mental Sharpness Actually in the Mouth?

A new international study published in PLOS ONE points to statistical links between the composition of tongue bacteria and cognitive performance. Researchers from the University of Exeter and Belgium tested dozens of adults and found that certain bacteria, such as Prevotella histicola, correlated with faster reaction times. However, the study is observational and small, and the researchers emphasize that a causal link or the ability to improve brain function by altering bacteria has not yet been proven.

A new international study published in the scientific journal PLOS ONE points to statistical links between the composition of tongue bacteria and performance on cognitive tests. A team led by the University of Exeter, in collaboration with researchers from Belgium, recruited 30 young adults and 30 adults in their sixties and seventies in each country. Participants underwent tests of memory, attention, emotion recognition, and cognitive speed, alongside saliva and tongue samples, blood tests, and blood pressure measurements. In the bacterial analysis, several notable findings emerged: a bacterium called Prevotella histicola was linked to faster reaction times in some tests in both countries. Another bacterium, Haemophilus parainfluenzae, showed mixed results—in Belgium it was associated with more accurate visual learning and working memory, while in the UK its effect on reaction speed was partially different. Age was the most significant predictor: older participants scored lower and reacted more slowly. The researchers emphasize that the study is observational and small, and that the chemical measurements were mixed and did not show a consistent line proving cause and effect. The study did not examine whether administering specific bacteria or dietary changes could improve brain function, and it did not account for factors such as precise diet, physical activity, or sleep. The conclusion: there is no evidence that altering oral bacteria can prevent dementia or slow brain aging.