A detailed review of pathophysiology, epidemiology, cellular and molecular pathways involved in the development and prognosis of Parkinson's disease with insights into screening models
Authors: Sayyaed Ayesha , Saraswat Nikita , Vyawahare Neeraj , Kulkarni Ashish 
Published: May 2023

AbstractBackgroundParkinson's disease is a neurodegenerative disorder of the central nervous system that is one of the mental disorders that cause tremors, rigidity, and bradykinesia. Many factors determine the development of disease. A comprehensive physical examination and medical history of the patient should be part of the differential diagnosis for Parkinson’s disease (PD). According to epidemiology, Parkinson’s disease majorly affects elderly persons and frequency of affecting men is more as compared to women where the worldwide burden of Parkinson’s disease (PD) increased more than twice in the past 20 years.Main body of the abstractIn this review paper, we discussed screening models, recent clinical trials, cellular and molecular pathways, and genetic variants (mutations) responsible for induction of Parkinson’s disease. The paper also aims to study the pathophysiology, epidemiology, general mechanism of action, risk factors, neurotoxin models, cellular and molecular pathway, clinical trials genetic variants of Parkinson’s disease. These models correspond to our research into the pathogenesis of Parkinson’s disease. The collected data for the review have been obtained by studying the combination of research and review papers from different databases such as PubMed, Elsevier, Web of Science, Medline, Science Direct, Medica Database, Elton B. Stephens Company (EBSCO), and Google open-access publications from the years 2017–2023, using search keywords such as “Cellular and molecular pathways, Clinical trials, Genetic mutation, Genetic models, Neurotoxin, Parkinson’s disease, Pathophysiology.”Short ConclusionMicroglia and astrocytes can cause neuroinflammation, which can speed the course of pathogenic damage to substantia nigra (SN). The mechanism of Parkinson’s disease (PD) that causes tremors, rigidity, and bradykinesia is a decrease in striatal dopamine. Genes prominently CYP1A2 (Cytochrome P450 A2),GRIN2A, andSNCAare Parkinson’s disease (PD) hazard factor modifiers. The most well-known neurotoxin is 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which destroys dopaminergic neurons, resulting in the development of Parkinson’s disease (PD). Dopamine auto-oxidation in dopaminergic (DA) neurons is a significant source of reactive oxygen species (ROS) that causes neuronal oxidative stress. Most common genes which when affected by mutation lead to development and progression of Parkinson’s disease (PD) areLRRK2,SNCA(alpha-synuclein protein), DJ-1, PRKN(Parkin protein),PINK1,GBA1, andVPS35. The commonly used neurotoxin models for inducing Parkinson's disease are 6-hydroxydopamine (6-OHDA), rotenone, paraquat, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and genetic models. Anti-apoptic drugs, gene mutation therapy, cell-based therapy, and plasma therapy were all discontinued due to insufficient efficacy. Because it is unclear how aging affects these molecular pathways and cellular functions, future research into these pathways and their interactions with one another in healthy and diseased states is essential to creating disease-specific therapeutics.