This book explores the rapidly advancing field of gut–brain interactions, with a particular focus on the emerging evidence linking the gut microbiome to neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, cerebral palsy, and amyotrophic lateral sclerosis (ALS). As scientific discoveries continue to illuminate how gut microorganisms influence brain structure and function, this work examines the mechanisms through which microbial imbalance contributes to disease onset and progression. By integrating cutting-edge findings on neuroinflammation, immune modulation, metabolic signaling, and neurotransmitter regulation, the book provides a comprehensive analysis of how the gut microbiome may act not only as a contributing factor but also as a promising therapeutic target. Each chapter highlights how disturbances in gut microbial ecology can trigger neuroinflammation, cognitive impairment, and motor neuron degeneration, while also presenting emerging therapeutic strategies including probiotics, prebiotics, dietary interventions, and fecal microbiota transplantation. Ultimately, this book offers an optimistic perspective on the development of microbiome-based, personalized interventions that hold the potential to transform the prevention and treatment of neurological disorders.