Advanced Parkinson's or "complex phase" Parkinson's disease? Re-evaluation is needed.

Holistic management of Parkinson's disease, now recognised as a combined motor and nonmotor disorder, remains a key unmet need. Such management needs relatively accurate definition of the various stages of Parkinson's from early untreated to late palliative as each stage calls for personalised therapies. Management also needs to have a robust knowledge of the progression pattern and clinical heterogeneity of the presentation of Parkinson's which may manifest in a motor dominant or nonmotor dominant manner. The "advanced" stages of Parkinson's disease qualify for advanced treatments such as with continuous infusion or stereotactic surgery yet the concept of "advanced Parkinson's disease" (APD) remains controversial in spite of growing knowledge of the natural history of the motor syndrome of PD. Advanced PD is currently largely defined on the basis of consensus opinion and thus with several caveats. Nonmotor aspects of PD may also reflect advancing course of the disorder, so far not reflected in usual scale based assessments which are largely focussed on motor symptoms. In this paper, we discuss the problems with current definitions of "advanced" PD and also propose the term "complex phase" Parkinson's disease as an alternative which takes into account a multimodal symptoms and biomarker based approach in addition to patient preference.

Palliative Care and Nonmotor Symptoms in Parkinson's Disease and Parkinsonism.

The term palliative care (PC) is defined as a collection of interventions and strategies that helps to improve and sustain the quality of life of patients and caregivers in situations and scenarios associated with life-threatening illness. This is usually implemented by means of early identification and treatment of relevant motor and nonmotor issues such as pain, sleep, and autonomic dysfunction, dementia, and depression. In addition, a holistic PC program also includes delivery of physical, psychosocial, and spiritual support. PC as a specific discipline, as well as a treatment strategy for long-term neurological conditions such as Parkinson's disease (PD), is relatively new, but very important as neurodegenerative disorders in the United Kingdom alone affects approximately 10 million people and there are over 130,000 people with PD. With longer life expectancy, the burden of long duration and late stage PD is even more evident, bringing in focus the need for PC. However, the concept of PC in PD is still poorly defined and although there are pockets of excellence, the strategy is poorly implemented into routine clinical practice. The variable progressive nature of the disease, the heterogeneity of clinical subtypes, and also the burden of nonmotor symptoms create challenges for effective PC delivery in PD, but recent clinical trials have started addressing PC in PD and are to be welcomed.

Personalized Medicine and Nonmotor Symptoms in Parkinson's Disease.

Parkinson's disease (PD) is a multineurotransmitter dysfunction related disorder resulting in a range of motor and nonmotor symptoms. Phenotypic heterogeneity is pronounced in PD and nonmotor symptoms dominant subtypes have been described. These endophenotypes may be underpinned by considerable nondopaminergic dysfunction; however, conventional treatment of PD continues to be mostly reliant on dopamine replacement strategy or manipulation of brain dopaminergic pathways. Consequently, treatment of many nondopaminergic nonmotor and some motor symptoms remains a key unmet need. It is also recognized that treatment strategies for PD are influenced by a number of nondrug-related issues. These include factors such as age, personality, and preferences for treatment, cultural beliefs, lifestyle, pharmacoeconomics, pharmacogenetics as well as comorbidity. Therefore, the success of clinical therapy will rest on how much these factors are considered to develop a truly holistic treatment plan. Personalized medicine is the modern way of delivering this holistic strategy for treatment of PD. Personalized medicine thus encompasses several strands of treatment. From the pharmaceutical point of view, it should involve dopaminergic and nondopaminergic strategies. In addition, there are substrategies involving precision and tailored medicine to suit the needs and requirements of individual patients. Precision medicine would be relevant for patients who may be at risk of developing the clinical syndrome of Parkinson's as identified by specific gene mutations. Precision medicine in this scenario will attempt to be preventive. Tailored medicine would address the "single multifactorial" complex nature of PD and address symptoms as well subtype-specific strategies. Personalized medicine is now practiced for other conditions such as oncology as well as diabetes. In this chapter, we discuss the rationale and the need to develop strategies for personalized medicine for PD.

Nonmotor Parkinson's and Future Directions.

Nonmotor symptoms (NMS) of Parkinson's disease (PD) are integral to the condition largely regarded as a motor syndrome. A range of NMS underpin the prodromal stage of Parkinson's and are present with variable frequency, range, and nature across the whole journey of a patient with Parkinson's from the onset of the motor disease to palliative stage. These symptoms also are key determinants of quality of life of the patient as well as the carer. Despite this, recognition management and focused treatment of NMS of PD remain poor. Future would, therefore, need to focus on better definition and management of NMS of PD. This would include development of robust animal models of specific NMS such as cognitive, sleep, and autonomic dysfunctions as well as pain to understand the mechanistic pathways of these symptoms. In turn this will lead to better drug development using a bench to bedside model. Nonmotor clinical subtypes of PD have also been described and, in future, proper biomarkers will consolidate these findings in addition to defining the natural history of the subtypes. Revised versions of established scales and questionnaires will enable the adoption of good clinical practice with recognition of these subtypes in clinic. This will enhance the delivery of true subtype-specific therapies. Drug development should also include nondopaminergic and cell replacement restorative therapies with a nonmotor focus. An additional key area of future research would be the formalizing of true personalized medicine for PD. Personalized medicine pathways should concentrate on the role of exercise, complementary medicine as well as age, body weight, ethnicity on various NMS of PD. Genetics and pharmacogenetic developments in PD will add to the precision of the individualized approach.

The Nonmotor Features of Parkinson's Disease.

Nonmotor symptoms (NMS) of Parkinson's disease (PD) were recognized by the great James Parkinson himself who mentioned symptoms such as sleep dysfunction, delirium, dementia, and dysautonomia, in his seminal 1817 essay, "An Essay on the Shaking Palsy" (Parkinson, 1817). In spite of the key impact of PD NMS on quality of life, there was little holistic research and awareness till the validation and use of comprehensive tools such as the NMS questionnaire, scale, and the revised version of the unified PD rating scale. Research studies using these tools highlighted the key impact of the burden of NMS on quality of life of PD patients and the need for NMS to be routinely assessed in clinic. We now define PD as a motor and nonmotor disorder, and the natural history includes a long prodromal phase of PD dominated by a range of NMS. The prodromal phase is the subject of much research particularly in relation to neuroprotection and identifying subjects at risk. Use of NMS tools has also validated burden grading of NMS with cutoff values, which can be used as outcome measure in clinical trials. Finally, the complex multineurotransmitter dysfunction that is seen in PD has been shown to manifest clinically as nonmotor subtypes. Recognition of such subtypes is likely to lead to the emergence of personalized and precision medicine in PD.