IS THERE a link between the gut and mental health? More specifically, is depression linked to gut bacteria? Scientists from Belgium set out to add another piece to this puzzle, and they recently published their results.
The study’s lead author, Prof Jeroen Raes, VIB-KU Leuven, Leuven, Belgium, acknowledged that the scientific community was currently divided, stating: “The relationship between gut microbial metabolism and mental health is a controversial topic in microbiome research.” He went on to note that while the idea of a link between gut microbes and the brain was captivating, the majority of scientific research to date had been conducted in animal models.
In this context, Prof Raes and his team conducted the first population-level study investigating the potential link between mental health and gut bacteria. They examined a microbiome population cohort of 1,054 individuals who were enrolled in the Flemish Gut Flora Project. Diagnoses of depression were based on the recommendation of general practitioners. The findings were validated against a cohort of clinically depressed patients and an independent cohort of individuals from the Dutch LifeLinesDEEP cohort (n= 1,063).
Prof Raes explained: “In our population-level study, we identified several groups of bacteria that co-varied with human depression and quality of life across populations.” The headline finding was that there were two bacterial genera that were found to be consistently depleted in those individuals with depression: Coprococcus and Dialister. These two genera were depleted even after correcting for the effects of antidepressants. An additional finding was that butyrate-producing Faecalibacterium and Coprococcus bacteria were regularly associated with higher quality of life indicators and that the ability of micro-organisms to produce a metabolite of the human neurotransmitter dopamine, DOPAC, was associated with a superior quality of life in terms of mental health and wellbeing.