In 1895, on turning 50, Elie Metchnikoff became increasingly anxious about ageing. As a result, the Russian Nobel prize-winning scientist,...
In 1895, on turning 50, Elie Metchnikoff became increasingly anxious about ageing. As a result, the Russian Nobel prize-winning scientist, and one of the founders of immunology, turned his attention away from immunology and towards gerontology – a term that he coined.
He was fascinated by the role that intestinal bacteria play in health and disease and suggested that people from parts of eastern Europe lived longer because they ate a lot of fermented foods containing lactic acid bacteria. Although popular at the time, this theory linking gut microbes to healthy ageing was largely ignored by scientists until relatively recently. We now recognise the importance that the trillions of bacteria, known as the gut microbiome, have in regulating health and disease.
Evidence has been accumulating for almost a decade that the microbiome composition changes with age. In 2012, research by my colleagues at University College Cork showed that diversity in the microbiome was linked to health outcomes in later life, including frailty. But we still did not know much about the effect of the microbiome on brain ageing.
In 2017, we revisited Metchnikoff’s ideas, putting them in the context of brain ageing, and showed that ageing induced changes in the microbiota and immune system, and was associated with cognitive decline and anxiety....
