Parkinson’s disease is on the rise — and despite the increased prevalence, early identification and diagnosis of the condition are eluding medical professionals and researchers.
As Parkinson’s disease is a progressive neurological disease, the signs and symptoms commonly don’t appear right away. Instead, in most cases, people with Parkinson’s disease slowly notice small changes in their physical and mental function, with more severe and debilitating symptoms emerging as the disease progresses over time.
Because of this, early detection and diagnosis of Parkinson’s disease are imperative — early diagnosis often leads to early access to treatment, which can significantly slow down the progression of the disease and prolong a person’s quality of life.
But unfortunately, being able to identify Parkinson’s disease during the early stages has proven to be a consistent challenge. As research continues to learn more about Parkinson’s, scientists and clinicians may be able to identify two new signs of early disease onset.
Using these two new early signs of Parkinson’s disease as a guide, will the way we approach Parkinson’s disease diagnosis change for the better?
Parkinson’s disease (PD) is a progressive neurological disorder primarily impacting the function and health of our brain. Belonging to the group of motor system disorders, people with Parkinson’s disease often experience uncontrollable and unintentional movements as a result of their diagnosis¹.
During the early stages of Parkinson’s disease, nerve damage in an area of the brain called the substantia nigra begins to impact the production of dopamine². The substantia nigra is a part of the brain responsible for the movement of our limbs. It is located in the basal ganglia, which is a centralized zone of the brain that acts as a connecting point for millions of different nerve synapses. As a result of the nerve damage, dopamine levels in the brain progressively decrease — and while some treatment options for Parkinson’s disease attempt to restore the amount of dopamine in the brain, the loss of substantia nigra nerve cells is permanent and currently incurable.
In addition to changes in dopamine levels, another theory for the cause of Parkinson’s disease is the development of Lewy bodies in the brain. Lewy bodies, defined as clumps of abnormal proteins that can often be found in nerve cells of those with Parkinson’s disease, interfere with the transmission of information from one nerve synapse to another³. Capable of migrating throughout the brain, it is currently suggested that Lewy bodies may be at least partially responsible for the development of motor and non-motor symptoms in people with Parkinson’s disease³.
It is not well understood why Parkinson’s disease-related nerve damage begins in the first place — but, unfortunately, once it does begin, it is near impossible to stop. As the extent of the nerve damage continues to worsen over time, the person will begin to experience changes to their motor function. Interestingly, in most cases, identifiable symptoms of Parkinson’s disease often don’t begin to appear until at least 80% of the substantia nigra has been permanently damaged⁴.
Like any other health condition, not everyone with Parkinson’s disease experiences symptoms the same way. Often differing in severity and order of presentation, there is no “one way” to have Parkinson’s disease — but there is a list of commonly seen signs and symptoms that can be used in the early diagnostic stage.
Examples of some of the most common symptoms of Parkinson’s disease include⁵:
Resting tremors — As one of the most commonly identified symptoms of Parkinson’s disease, resting tremors refer to a constant and uncontrollable shaking of the hands, legs, jaw, or head. In some cases, people with Parkinson’s display a type of tremor called pill-rolling, where they repetitively rub their thumb and forefinger together involuntarily. Unlike other types of tremors that can present themselves when a person tries to initiate an action, people with Parkinson’s disease commonly experience tremors while at rest, are usually unilateral (one-sided), and often only stop once they fall asleep⁶. Depending on the severity of the person’s tremor, performing basic tasks such as eating, personal hygiene, and walking can become increasingly difficult.
Stiffness — Muscle rigidity and stiffness are common symptoms of Parkinson’s disease. Often impacting a person’s limbs and trunk, muscle stiffness can make initiating movements more difficult and lead to significant discomfort and pain over time.
Bradykinesia — Defined as the progressive slowing of movements, bradykinesia is a common symptom of later-stage Parkinson’s disease. As the amount of dopamine available in the person’s brain continues to decrease, initiating movements like walking or standing up from a chair becomes more and more difficult. This will result in all movements becoming more time-consuming and energy-draining, which can lead to increased frustration for the person with the disease, their family, and caregivers.
Poor balance — Posture and balance are often impacted by Parkinson’s disease. As a person’s balance begins to become challenged due to the changes in their brain function, it is common for their posture to become more stooped over and hunched. Additionally, people with Parkinson’s disease are at an elevated risk of getting injured from falling due to their condition.
Shuffling gait — Associated with increased stiffness and poorer balance, a person with Parkinson’s disease will experience a change in their gait (how they walk). In most cases, people with Parkinson’s walk with short and small strides, often dragging or shuffling their feet with each step as the disease progresses.
Mood and memory changes — Mood disorders such as depression and anxiety are common in people diagnosed with Parkinson’s disease. Additionally, changes in long and short-term memory can also begin to appear in people with Parkinson’s disease.
Sleep disorders — Even though people with Parkinson’s disease experience increased fatigue, sleep disturbances are incredibly common. Including common sleep issues such as insomnia, restless leg syndrome, and more, impaired sleep goes hand in hand with poorer health outcomes and increased risk of injury⁶.
Chronic pain — Due to increased muscular rigidity and resting tremors, it is very common for people with Parkinson’s disease to experience chronic pain. Long-term management of Parkinson’s disease-related pain is one of the most important aspects of any treatment plan for the disorder.
Constipation and urinary frequency — In addition to movement-related symptoms, Parkinson’s disease can also impact a person’s gastrointestinal and urinary health. As a result, it is common for people with Parkinson’s to experience increased constipation (difficulty producing stool) while also experiencing urinary frequency (the feeling of needing to pass urine more frequently than normal). Depending on the extent of the person’s motor symptoms, toileting can become a more complex issue over time.
Difficulty swallowing — As the disease progresses, motor function and tremors can impair a person’s ability to swallow food and drinks. Depending on the severity of symptoms, a person may be unable to properly chew or swallow their meals, which can put them at risk of aspiration (choking on food or fluids). In most cases, people with later-stage Parkinson’s disease often eat a soft food diet to reduce their risk of aspiration.
So, as we can see, many different symptoms can present themselves as Parkinson’s disease progresses — but depending on the person, the development of identifiable symptoms may only occur after substantial neurological damage has already occurred.
Looking to learn more about other potential early warning signs of the disease, a 2022 study of over one million health records from East London was conducted⁷. Throughout the study, two interesting and noteworthy findings were presented⁷:
Taking health records from 1998-2018, it was found that, on average, people with Parkinson’s begin to show symptoms such as tremors and memory problems anywhere from 5–10 years prior to an official diagnosis of Parkinson’s disease. This indicates that our current system for diagnosis of the disease regularly delays access to treatment for the disease by up to a decade, which can worsen a person’s overall quality of life and life expectancy.
Through the analysis of health records of those who eventually developed Parkinson’s disease, two previously unknown early features of the disease were found — epilepsy and hearing loss. Interestingly, this finding was able to be confirmed by another data set collected from the United Kingdom Biobank.
As a result of this groundbreaking study, researchers are hopeful that the modern approach to Parkinson’s disease diagnosis will continue to improve, allowing for earlier access to treatments that slow the progression of the condition.
So, now that we know that there are new early signs of Parkinson’s disease, how can this information inform how we approach identifying and treating the disease?
Because Parkinson’s disease is such a slow-moving progressive disorder, awareness and improved education about the early signs of Parkinson’s disease are essential in getting people better access to the care they need. But, with some people with Parkinson’s disease taking over twenty or more years to progress through the most common symptoms, it can be hard to know what level of care and attention each person requires. With this problem in mind, the Parkinson’s disease staging system was created⁸:
Stage 1 — As the first stage of the disease, most people receive their formal diagnosis of Parkison’s disease while displaying mild symptoms that fit this category. During stage 1, mild tremors and motor skill loss may occur on one side of the body only, and mild changes in a person’s walking gait and balance may develop. According to new research findings, this is also the stage where a person may be diagnosed with epilepsy and hearing loss.
Stage 2 — During stage 2, symptoms begin to worsen progressively. In most cases, mild tremors will start to migrate from one side of the body to the midline while also causing an increase in muscle rigidity. It is possible for a person with stage 2 Parkinson’s disease to live alone, but they will notice that basic daily tasks will have become more difficult and will take more time to complete.
Stage 3 — Considered to be the being of mid-stage Parkinson’s disease, people with stage 3 Parkinson’s disease begin to experience more profound symptoms. Often characterized by poorer balance and increased risk of falls, this is the stage where a person may begin to require additional assistance with activities of daily living.
Stage 4 — At this point in the disease progression, the symptoms of Parkinson’s disease will be severe and debilitating. Often unable to stand on their own without assistance and supervision, people in this stage of Parkinson’s disease require assistive care to safely practice daily activities.
Stage 5 — As the final stage of Parkinson’s disease, symptoms of the disorder are the most advanced and debilitating. In some cases, the person may no longer be able to stand and must use a wheelchair with assistance for ambulation. People with stage 5 Parkinson’s disease require 24-hour care to meet their basic needs.
So, as we can see, plenty of research still needs to be done to better understand the cause of Parkinson’s disease — and as we get closer to uncovering these secrets, more and more advances in our current diagnostic and treatment options will continue to occur.
While we currently do not have a cure for Parkinson’s disease, educating yourself about the early signs of the disease is one of the best ways to protect yourself and your loved ones from living with undiagnosed Parkinson’s disease.
If you begin to notice slow and consistent changes in the mental or physical behaviors in yourself or in a family member (particularly newer symptoms that you may not associate with Parkinson’s disease, such as epilepsy and hearing loss), speak to your primary care provider about monitoring for Parkinson’s disease is an essential first step in getting connected to the specialists needed to properly manage and diagnosis the disease.
Parkinson's disease | NIH: National Institute of Neurological Disorders and Stroke
Parkinson’s disease | American Association of Neurological Surgeons
The relevance of the Lewy body to the pathogenesis of idiopathic Parkinson's disease. (1988)
Causes | NHS
Parkinson's disease | MedLine Plus
Assessment of risk factors and early presentations of Parkinson's disease in primary care in a diverse UK population (2022)
Stages of Parkinson's | Parkinson's Foundation
Claire Bonneau is a medical writer and certified trauma operating room nurse.
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