Hearing Loss and Epilepsy: Two Early Signs of Parkinson's Disease

Hearing loss and epilepsy have been identified as two early signs of Parkinson's disease, according to research published in 2022 in JAMA Neurology. That information and other symptoms seen in the years before a diagnosis may help healthcare providers recognize and treat the disease at earlier stages.

"Our results uncovered novel risk factors and early symptoms: epilepsy and hearing loss," lead study author Cristina Simonet, MD, said in a press release. "It's important that primary care practitioners are aware of these links and understand how early the symptoms of Parkinson's can appear so that patients can get a timely diagnosis."

The study is one of the first from the United Kingdom to look at neurodegenerative disorders in a large, diverse population. Though researchers found neither ethnicity nor socioeconomic status increased the risk of developing Parkinson's disease, the study still provides a more in-depth look at how the disease affects all people, even in the years leading up to diagnosis.

Here's what you should know about how epilepsy and hearing loss may be an early symptom indicating the onset of Parkinson's disease.

Epilepsy and Hearing Loss as Signs of Parkinson's

The goal of the study, conducted by researchers at the Queen Mary University of London, was to investigate risk factors and prediagnostic symptoms in an ethnically diverse population since most Parkinson's disease research has been done in predominantly white, affluent populations.

Scientists analyzed the medical records of over one million people living in East London between 1990 and 2018. The researchers chose East London, specifically, because it offered a highly diverse population with "high socioeconomic deprivation," the study said. In East London, about 45% of residents are Black, South Asian, mixed, or belonging to another ethnic group.

One of the most "notable" findings, according to researchers, was that having epilepsy was associated with a higher risk of developing Parkinson's disease. Though researchers said drug-induced Parkinson's disease could not be ruled out in this case, that isn't the first time epilepsy has been linked to the condition. Case reports from 2016 found that Parkinson's disease and epilepsy can coexist by predating a diagnosis or developing after one.

Hearing loss was another finding of the study, occurring up to five years before a diagnosis. 

"It's an interesting observation because it's the first time that that has been seen with Parkinson's," Aaron L. Ellenbogen, DO, a neurologist at the Michigan Institute for Neurological Disorders in Farmington Hills, Mich., told Health. "Further exploration is really critical in understanding if it's more than just the observation and if there's truly some underlying mechanism that really links the two together."

Other Early Signs of Parkinson's

Though study authors agree that more research is needed regarding hearing loss and its link to Parkinson's disease, they suggest it's part of the impairment in sensory processing that occurs with the condition. That impairment may manifest in different ways—through sight, hearing, or even sense of smell, researchers said.

In addition to the new potential signs and risk factors, researchers noticed novel trends in well-known symptoms. Tremors—involuntary muscle contractions—were found to show up as many as 10 years before a Parkinson's disease diagnosis, becoming more frequent in the two years leading up to one.

And memory problems, which were the most frequently reported non-motor symptom associated with Parkinson's, could appear up to five years before diagnosis. 

The disease was also positively associated with other comorbidities (high blood pressure, low blood pressure, type 2 diabetes) and other prediagnostic signs and symptoms (constipation, depression, erectile dysfunction).

"Parkinson's, even though many think of it as a brain disorder, it really affects a number of systems throughout the body," said Dr. Ellenbogen. "It's not simply about motor aspects: It impacts the gastrointestinal system, the genital urinary system, sleep, cognition. And I think that's often lost on people."

Many people with Parkinson’s disease indicate that besides tremors, they experience stiffness, sleep problems, constipation, loss of smell, and restless legs.

However, Dr. Ellenbogen clarified that a symptom or risk factor associated with Parkinson's disease doesn't definitively mean it will cause the disease. 

"If a person develops constipation [...], it shouldn't necessarily lead to the [thought] that they're developing Parkinson's disease," said Dr. Ellenbogen, adding that there's a "tremendous number of reasons" why someone can develop constipation that isn't related to Parkinson's.

Other early signs and symptoms of Parkinson's disease include:

• Tremors
• Stiffness
• Memory problems
• Sleep problems
• Constipation
• Loss of smell
• Restless legs
• GI/urinary issues

Symptoms of Parkinson's Disease

There is no official screening test for Parkinson's. Still, the results of the study give hope of being able to detect and ultimately treat people at high risk for Parkinson's disease earlier than normal.

Guy Schwartz, MD, a movement disorders neurologist and co-director of the Parkinson's disease and Movement Disorders Center at Stony Brook Medicine, told Health that people should see a healthcare provider for Parkinson's disease if they experience a combination of symptoms.

Parkinson's disease is tricky because it has a constellation of symptoms that are specific and nonspecific to the disease. Fortunately, there are multiple symptoms that more directly relate to Parkinson's disease. One hallmark of the disease is motor control issues, including:

• Tremors in the hands, arms, legs, jaw, or head
• Stiffness of the limbs or trunk
• Slowness of movement
• Impaired balance or coordination

Identifying non-motor symptoms, even ones that occurred previously, rather than waiting for motor symptoms could also help with an earlier diagnosis. That's especially because motor symptoms can be very subtle at the beginning of the disease. 

"Because slowness of movement is often seen at higher rates in older people, we also run into the problem of differentiating what is normal aging versus what is Parkinson's disease," explained Dr. Ellenbogen.

Some non-motor symptoms of Parkinson's disease include, but aren't limited to:

• Pain
• Sleep disorders
• Excessive sweating
• Mood disorders
• Sexual problems
• Fatigue

"The diagnosis of Parkinson's disease really starts with the appearance of physical signs. Identifying two out of four [motor] symptoms is sufficient for a clinician to make the diagnosis of Parkinson's," added Dr. Schwartz. "It's not always so straightforward, but that is the foundation."

An internist or primary healthcare provider is usually one of the first to make a diagnosis. People who are showing early symptoms of Parkinson's disease—even subtle signs—should start there and potentially go on to seek further testing and treatment from a movement disorder specialist.

A Quick Summary

Parkinson's disease is a brain disorder that causes unintended or uncontrollable movements, such as shaking, stiffness, and difficulty with balance and coordination. Research has identified epilepsy and hearing loss as two early signs of Parkinson's disease.

Because there are currently no blood or laboratory tests to diagnose non-genetic cases of Parkinson's disease, a healthcare provider must consider the symptoms a person is presenting with.