Biomarkers of Non-Motor Symptoms in Parkinson’s Disease and Parkinsonisms

Parkinson’s disease and other forms of parkinsonism are debilitating neurological conditions characterized by motor symptoms (indeed, parkinsonism). Nevertheless, non-motor symptoms (NMS) are a relevant aspect of the clinical picture: NMS encompass autonomic, gastro-intestinal, sleep, sensorial, cognitive, and psychiatric disturbances. Notwithstanding their prevalence and impact on quality of life, disability, and prognosis, they are often overlooked. Importantly, NMS can precede motor symptoms, as in the case of prodromal Parkinson’s disease: a stage wherein early symptoms or signs of neurodegeneration are present, but clinical diagnosis is not yet possible due to the lack of motor manifestations. Biomarkers are needed to better characterize and assess NMS and to elucidate underlying pathological mechanisms. Moreover, biomarkers can improve diagnostic accuracy and help monitor disease progression. Biomarkers include clinical and neurophysiological assessments, imaging, and “wet biomarkers” (such as cerebrospinal fluid and blood biomarkers) encompassing biochemical assessments and genomic/proteomic/metabolomic/RNA methodologies.

In the past years, NMS have gained great recognition as relevant symptoms of Parkinson’s disease and parkinsonism, in virtue of their impact on health-related quality of life and prognosis; research on prodromal phases of disease has significantly expanded, mainly due to its role in the identification of a target population for neuroprotective therapies. At the same time, technological progress has propelled the advances in the field of biomarkers. The aim of this Research Topic is to update the state of the art in this field - that comes from the intersection of these rapidly advancing fields - to equip movement disorders experts with the latest knowledge on biomarkers of NMS, in order to implement them in their research and clinical activity, and to provide a better understanding of NMS clinical manifestations and therapeutic management. Moreover, this research topic aims at unraveling the mechanisms leading to NMS by investigating their association with biomarkers alterations to specific neurodegenerative pathways, in order to provide new insights and foster the discussion on potential therapeutic approaches.

This Research Topic welcomes any types of manuscripts supported by the Journal (e.g., Original Research works, Reviews, Brief Reports, Perspectives and Hypothesis, Opinions, and Theory manuscripts) with contributions to the understanding of biomarkers of NMS in Parkinson's disease and other forms of Parkinsonism.
The subtopics include the application of different biomarkers to better characterize NMS in every stage of the disease, including the prodromal stage. A biomarker should be objective and reproducible independent from the subjective “signs” perceived by the patients. Articles on combinations of biomarkers are welcome.

NMS include, but are not limited to, the following:
• Gastrointestinal symptoms
• Cognitive dysfunction
• Psychiatric manifestations
• Sensory disturbances
• Sleep disorders
• Anosmia
• Genito-urinary symptoms
• Autonomic symptoms
• Cardiovascular symptoms
• Others (e.g. sweating alterations, etc.)

Examples of biomarkers include, but are not limited to, the following:
• Imaging techniques (including neuroimaging and imaging of other districts)
• Cerebrospinal fluid (CSF) and blood biomarkers
• Histological biomarkers
• Genetic, epigenetic and “-omics” markers
• Neurophysiological markers
• Others (e.g. microbiome, etc.)

Keywords: Biomarkers, non-motor symptoms, Parkinson’s disease, Parkinsonism, neuroimaging, prodromal stage

Important note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.