Chapter 36 - The role of the gastrointestinal system and gut microbiota in Parkinson's disease

Abstract

Parkinson's disease (PD) is a common neurodegenerative disorder that affects approximately 10 million people worldwide. This debilitating neurological disorder is a progressive disease, primarily diagnosed and characterized by the onset of four cardinal motor symptoms: tremor, rigidity, bradykinesia, and postural instability. However, PD also has an array of nonmotor symptoms, including sleep disturbances, cognitive decline, and gastrointestinal (GI) dysfunction. Often underappreciated, associated GI symptoms can manifest up to 2decades prior to the initial presentation of clinically defining cardinal motor symptoms. This has led to research into the composition of specific gut microbes in individuals with PD, highlighting a potential role for gut microbiota in modulating systemic inflammation and symptomatic progression. To this end, investigating the GI-associated and microbial changes in PD patients could improve the preclinical diagnosis and aid in the identification of patient populations for future disease modifying trials. In this chapter we describe the GI-associated symptoms of PD and highlight the immunomodulatory role of the gut microbiome as a potential regulator of the PD phenotype.