This month is Parkinson’s Disease Awareness month and, even as a child neurologist, I find myself thinking about how much we have learned and how much we have yet to learn about this common neurodegenerative condition.
Parkinson’s disease is a progressive movement disorder that primarily affects people over the age of 65. However, an estimated four percent of people with Parkinson’s are diagnosed with “early onset Parkinson’s disease,” meaning that they were diagnosed before age 50. Clinically, Parkinson’s disease is characterized by slowness of movement (bradykinesia), rhythmic shaking of the limbs and head (tremor), inflexibility of the limbs (rigidity), and loss of the balancing mechanism (postural control).
In addition to these classic “motor” or movement-related symptoms, people with Parkinson’s also experience a range of symptoms affecting daily activities, including fatigue, pain, changes in mood and thinking, difficulties sleeping, issues with eating and swallowing, and bladder and bowel problems. Under the microscope, the brains of patients who had Parkinson’s disease all show abnormal clumps of proteins, called Lewy bodies, and the loss of nerve cells that make the chemical dopamine.
What has become clear is that Parkinson’s represents a complex spectrum with shared characteristics, including a classic trio of motor symptoms and similar end-term brain changes, but also with a range of physical manifestations such that the experience of each person with Parkinson’s is unique.
What makes a person susceptible to Parkinson’s? Parkinson’s is diagnosed across ethnic groups, socioeconomic class, in rural and urban areas, around the globe, and is expected to increase as the population ages. Most people with Parkinson’s do not have relatives with it, suggesting that something in the environment may initiate a cascade of events leading to loss of dopamine neurons and changes in movement. That said, some forms of Parkinson’s may be inherited, as approximately ten percent of people with Parkinson’s carry a gene that increases risk of developing the condition. This has led to the hypothesis that both genetic and environmental factors contribute to the onset of Parkinson’s disease.
However, this relationship is complicated. Whether or not a person with genetic risk eventually develops Parkinson’s seems to depend, in part, on their age and other risk factors. Whether an environmental factor is sufficient to initiate Parkinson’s may depend, in turn, on genetic risk. The roles of environmental, genetic, and other potential contributing factors, including lifestyle (e.g. exercise, nutrition), inflammation, microbiome (microorganisms living in the human body, such as bacteria), are under active investigation.
Research funded and performed, not just by NINDS but also by our many nonprofit organization partners, is seeking to understand the contribution of the causes of Parkinson’s, discover new and improve existing treatments and, ultimately, find a cure for Parkinson’s. Earlier this year, the NINDS hosted a meeting with our partners including the Michael J. Fox Foundation, Aligning Science Across Parkinson’s, Parkinson’s Foundation, American Parkinson Disease Association, Parkinson Alliance and Davis Phinney Foundation to discuss current research needs in Parkinson’s disease research and treatment. We are actively collaborating on common goals to serve the Parkinson’s community through increasing our understanding of shared clinical symptoms, individual manifestations and underlying biological pathways that lead to Parkinson’s.
So is Parkinson’s really many different diseases that all have bradykinesia, tremor, rigidity, and loss of postural control as their hallmarks? Are there many different “roads” that lead to the same clinical destination? This seems highly likely. As a child neurologist, I find myself wondering if there could be ways to predict the onset of Parkinson’s at a time early enough to prevent damage from occurring.
Ongoing research focused on identifying and finding targets for preventive measures and therapies in these separate “roads” to Parkinson’s disease and determining a “final common pathway” would allow us to prevent or treat Parkinson’s disease. As we mark Parkinson’s Disease Awareness Month, the NINDS and our dedicated partners continue to support research that builds on a foundation of current knowledge, addresses the unknown, and provides a new road map leading to improved understanding of and treatment for Parkinson’s disease.
NINDS Resources for Parkinson’s Disease: