The concept of ‘idiopathic’ Parkinson’s disease (PD) as a single entity has been challenged with the identification of several clinical subtypes, pathogenic genes and putative causative environmental agents. In addition to classic motor symptoms, non-motor manifestations (such as rapid eye movement sleep disorder, anosmia, constipation and depression) appear at prodromic/premotor stage and evolve, along with cognitive impairment and dysautonomia, as the disease progresses, often dominating the advanced stages of the disease. The key molecular pathogenic mechanisms include α-synuclein misfolding and aggregation, mitochondrial dysfunction, impairment of protein clearance (associated with deficient ubiquitin-proteasome and autophagy-lysosomal systems), neuroinflammation and oxidative stress. The involvement of dopaminergic as well as noradrenergic, glutamatergic, serotonergic and adenosine pathways provide insights into the rich and variable clinical phenomenology associated with PD and the possibility of alternative therapeutic approaches beyond traditional dopamine replacement therapies.One of the biggest challenges in the development of potential neuroprotective therapies has been the lack of reliable and sensitive biomarkers of progression. Immunotherapies such as the use of vaccination or monoclonal antibodies directed against aggregated, toxic α-synuclein.as well as anti-aggregation or protein clearance strategies are currently investigated in clinical trials. The application of glucagon-like peptide one receptor agonists, specific PD gene target agents (such as GBA or LRRK2 modifiers) and other potential disease modifying drugs provide cautious optimism that more effective therapies are on the horizon. Emerging therapies, such as new symptomatic drugs, innovative drug delivery systems and novel surgical interventions give hope to patients with PD about their future outcomes and prognosis.

Parkinson disease (PD) is a chronic, progressive neurological disorder characterized by motor and nonmotor features.¹ Treatments primarily target symptoms but do not slow or halt the underlying neurodegeneration.² Eventually, debilitating adverse effects and treatment-resistant symptoms emerge. Therefore, there is a profound unmet need for disease-modifying therapies.

This review examines currently available therapeutic strategies for Parkinson's disease, emphasizing evidence-based data as well as a patient-centered approach to the treatment of motor and nonmotor symptoms. Although clinical trials of disease-modifying approaches have been thus far disappointing, steady advances are being made in the symptomatic treatment of Parkinson's disease. In this review, we focus on recent studies with monoamine oxidase type B inhibitors (selegiline and rasagiline), coenzyme Q10, creatine, and exercise in early Parkinson's disease. We also discuss the relative merits and disadvantages of delaying the initiation of levodopa therapy, the role of dopamine agonists, particularly ropinirole and pramipexole, and management of motor and behavioral complications, such as fluctuations, dyskinesias and impulse-control disorders. Novel formulations and delivery approaches for conventional and new drugs are also discussed. Finally, we review recent studies of surgical treatments of Parkinson's disease, such as deep brain stimulation. Numerous clinical trials have provided evidence that health-related quality of life can be substantially improved with early diagnosis and institution of exercise and other physical measures, appropriate timing of dopaminergic therapy, and strategies to delay and treat levodopa-related motor complications and nonmotor Parkinson's disease-related symptoms.