Scientists at University College London have identified distinctive changes in gut bacteria that can flag a person's risk of developing Parkinson's disease long before clinical symptoms emerge, according to research published in Nature Medicine. Analysing faecal and clinical data from hundreds of participants across the UK, South Korea, and Turkey, the team found that over 176 microbial species showed altered abundance in Parkinson's patients — a pattern also present, to a lesser degree, in people carrying a genetic risk gene but not yet diagnosed. Researchers believe the microbial changes may promote the build-up of a protein called alpha-synuclein, which damages brain neurons, and the findings raise hopes that dietary adjustments or microbiome-targeted therapies could eventually help prevent or delay the disease, which now affects more than 8.5 million people worldwide.