Parkinson’s Disease – The Pandemic in the Making?

The thoughts of another pandemic while already in the grips of one sends chills down our spines! So, without further ado, let us see if we can nip it in its bud. Although not contagious, unlike COVID-19, there is indeed reason to tout it as a pandemic in the foreseeable future, at least according to the leading Dutch neurologist Dr. Bastiaan R. Bloem. Researchers explain that this condition is communicable via new types of vectors – namely, social, political, and economic trends.

Parkinson’s disease (PD) is a progressive neurodegenerative disorder, mainly affecting the aged population. Although primarily a movement disorder, patients also suffer from non-motor symptoms, such as depression, anxiety, fatigue, and sleep disorders. The cause of this disorder is mostly unknown, and a subject of active research. The current mode treatment primarily involves medication like levodopa and others (e.g., dopamine agonists, monoamine oxidase-B (MAO-B) inhibitors, catechol-O-methyltransferase (COMT) inhibitors, anticholinergics, glutamate antagonists, and medication against non-motor symptoms), most often in combination with levodopa. Along with these, supportive therapy, including physiotherapy, occupational therapy, speech and language therapy and changes in diet, are frequently prescribed. In cases where medication is ineffective, surgery (mostly deep brain stimulation, and rarely, lesioning surgery) is prescribed.

PD is the fastest growing neurological disorder globally, and the spike has been attributed to the increasing human lifespan, the reduction in the number of smokers, and an increase in the number of industrial pollutants like the herbicide paraquat in the recent decades. Researchers believe that the key to transforming this seemingly inevitable rise in PD is activism, e.g., raising awareness, amassing funds, improving treatments, and changing policy. Stopping the production and use of the chemicals that may increase the risk of PD is essential. Also, crucial, as ever, is financial backing. More research is needed to understand why the condition appears and how it progresses, and this type of scientific investigation is never cheap. The most effective therapy remains levodopa, which is 50 years old and not without its issues, including both psychological and physical side effects.

Two hundred years since its first description, the scientists’ understanding of PD has made unimaginable progress, but there is hardly much in terms of treatment to show for it. PD is driven by the loss of dopamine-containing neurons in the brain, particularly those in the substantia nigra. For decades, researchers mimicked this pattern of cell death in animals using toxins, but the insights gleaned did not translate to humans, leading to a raft of failed clinical trials. Many failed clinical trials later, pharmaceutical company investment has withered as PD is deemed too high risk. In response, researchers are getting back to basics: re-examining their animal models, monitoring PD symptoms over years to better understand the different ways the disease unfolds, looking for early signs of the disease, and refining clinical trials so that effective therapies will not be missed. With a better understanding of the challenges, a new generation of treatment ideas is now in clinical trials, some of which aim to stall progression of the disease. A new study casts PD as an autoimmune disorder, with evidence that the immune system mistakenly attacks neurons and the alpha-synuclein protein (the normal physiological function of the α-synuclein protein involves roles in compartmentalization, storage, and recycling of neurotransmitters, and mutations in the SNCA gene that encodes it facilitates its aggregation and the Parkinson pathology). The emerging complexity of PD biology suggests that future treatment may involve multiple targets.

To quote Dr. Bloem, “From 1990 to 2015, the number of people with Parkinson disease doubled to over 6 million. Driven principally by aging, this number is projected to double again to over 12 million by 2040. Additional factors, including increasing longevity, declining smoking rates, and increasing industrialization, could raise the burden to over 17 million. For most of human history, Parkinson has been a rare disorder. However, demography and the by-products of industrialization have now created a Parkinson pandemic that will require heightened activism, focused planning, and novel approaches.” This year, a promising molecule has offered hope for a new treatment that could stop or slow Parkinson's, something no treatment can currently do. Also, the link with environmental toxicants is a trending topic of research.

So, worrying as the recent analysis is, there is reason to keep the hope alive in our hearts that the Parkinson pandemic is preventable, not inevitable.