biostudies-literatureBicknell Bprivate donor368https://www.ebi.ac.uk/biostudies/studies/S-EPMC12786582biostudies-literatureUnknown15(1)<b>Background</b>: Parkinson's disease (PD) involves progressive neurodegeneration with clinical or subclinical disturbance of the gut-brain axis, including altered gastrointestinal motility and enteric nervous system involvement. Clinical studies have reported gut microbiome alterations in PD, with shifts in taxa associated with inflammatory signalling and short-chain fatty acid (SCFA) metabolism. Photobiomodulation (PBM), a non-invasive light therapy, has been investigated as a potential adjunctive treatment for PD, with proposed effects on neural, metabolic, and immune pathways. We previously reported the five-year clinical outcomes in a PBM-treated Parkinson's disease case series. Here we report the five-year gut microbiome outcomes based on longitudinal samples collected from the sameJournal of clinical medicineFive-Year Follow-Up of Photobiomodulation in Parkinson's Disease: A Case Series Exploring Clinical Stability and Microbiome Modulation.PMC12786582NAMcLachlan CKiat HBicknell BLiebert AfalseFive-Year Follow-Up of Photobiomodulation in Parkinson's Disease: A Case Series Exploring Clinical Stability and Microbiome Modulation.<b>Background</b>: Parkinson's disease (PD) involves progressive neurodegeneration with clinical or subclinical disturbance of the gut-brain axis, including altered gastrointestinal motility and enteric nervous system involvement. Clinical studies have reported gut microbiome alterations in PD, with shifts in taxa associated with inflammatory signalling and short-chain fatty acid (SCFA) metabolism. Photobiomodulation (PBM), a non-invasive light therapy, has been investigated as a potential adjunctive treatment for PD, with proposed effects on neural, metabolic, and immune pathways. We previously reported the five-year clinical outcomes in a PBM-treated Parkinson's disease case series. Here we report the five-year gut microbiome outcomes based on longitudinal samples collected from the same2026-01-01T00:00:00Z2026 Jan2026-06-09T03:09:34.501Z2026-06-09T03:07:22.233ZS-EPMC127865824151762210.3390/jcm15010368