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Headlines 15 P arkinson's disease (PD) is often synonymous with tremors and impaired motor skills, but the disease is far more complex than its overt symptoms suggest. Constipation is an often overlooked but significant symptom of PD, manifesting years before the more commonly recognised motor symptoms. Ongoing gastrointestinal issues are an early warning sign of disruptions in the gut-brain axis, an intriguing area of PD research that plays a role in the onset and progression of the disease. The gut microbiome is a bustlingmetropolis of microbes, each with its role in nutrient absorption, immune function, andmental health. This microbial community is not just a passive resident; it's an active participant in our wellbeing. The gut is implicated in various conditions, frommetabolic disorders like diabetes to autoimmune diseases and certain cancers. The gut-brain communication highway The gut and the brain are in constant dialogue, thanks to a complex network of neurotransmitters like serotonin and dopamine. These chemicals not only regulate mood but also play a crucial role in motor functions, which are often compromised in PD. The gut produces these neurotransmitters, acting as a biochemical mediator between the brain and the body. When this gut-brain communication is disrupted — often due to an imbalance in the gut microbiome — it can trigger a cascade of inflammatory responses. This inflammation can spread throughout the body and reach the brain, setting the stage for neurodegenerative diseases like PD. Recent research shows that individuals with PD have a distinct gut microbiome composition compared to those without the disease. Certain bacterial species are found in abundance, while others are notably reduced. This microbial imbalance is not just a consequence of the disease, but also a contributing factor. The gut microbiome's potential as a therapeutic target is increasingly acknowledged, offering a new avenue for slowing down or even halting the progression of PD. The power of diet: fibres and fatty acids Dietary choices profoundly impact the gut microbiome and, by extension, PD. Foods rich in fibres, like spinach, artichokes, and asparagus, can enhance the production of short-chain fatty acids in the gut. These short-chain fatty acids have anti-inflammatory properties that modulate neurotransmitter levels, offering a dietary intervention strategy for PD patients. Other therapies Beyond diet, more direct clinical interventions are being developed each offering unique advantages in managing PD. Among these are faecal microbiota transplantation, which is like a reset button for the gut, and psychobiotics. Faecal microbiota transplantation Faecal transplantation is akin to a system reset for your gut microbiome. It involves the transfer of faecal matter from a healthy donor into a patient's gastrointestinal tract. Preliminary studies indicate that faecal microbiota transplantation improves gastrointestinal and neurological symptoms in PD patients, including quality of life and cognitive function. The procedure is generally considered safe but requires rigorous donor screening to prevent the transfer of pathogens or harmful bacteria. Psychobiotics: the mind-gut connection Psychobiotics are a specialised subset of probiotics designed to positively influence mental health. These are not your garden-variety Lactobacillus or Bifidobacterium strains found in yoghurts and other gut-healthy foods. Psychobiotics are specifically engineered to produce or modulate neurotransmitters like serotonin and dopamine. Early research suggests that these probiotics can ameliorate symptoms of anxiety and depression, which are often comorbid with PD. The potential here is not just symptom relief but a targeted approach to mental wellbeing, which is crucial given the emotional and cognitive challenges PD patients frequently face. The most exciting prospect lies in the potential synergy between these therapies. Imagine a treatment regimen that starts with faecal microbiota transplantation resetting the gut microbiome, followed by a tailored psychobiotic regimen to boost mental health. This could offer a multi-pronged approach to managing PD, addressing its physical and emotional dimensions. The gut-brain axis offers a revolutionary perspective on PD, shifting the focus from the brain to an integrated approach that includes gut health. By understanding the intricate relationship between our gut microbiome and the brain, we open the door to innovative treatments beyond symptommanagement to address the root causes of this debilitating disease. The gut may very well be the frontier where the battle against Parkinson's disease is won, offering hope to millions affected by this condition worldwide. Dr Victor Dieriks is Senior Research Fellow in Anatomy and Medical Imaging at the University of Auckland. In 2020 he received a $86,000 grant from the Neurological Foundation to study the formation of toxic clumps of alpha-synuclein protein in the brains of Parkinson’s disease patients. If you would like to know more or wish to get in touch with Dr Dieriks, visit Dierikslab.com The Liggins Institute at the University of Auckland has been exploring the importance of the gut microbiome for a wide range of conditions. Researchers there have been running clinical trials that involve the transfer of gut microbiome via a small capsule from healthy donors to people with a disordered gut microbiome. Clinical studies are underway testing the treatment on groups of patients with obesity, autism or with anorexia nervosa.