‘Most Diverse’ Study Finds Symptoms Start Up to 10 Years Before Diagnosis

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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Data from a new U.K. study with the most diverse group of patients ever reported show that Parkinson’s disease symptoms — including tremors, cognitive difficulties, epilepsy, and hearing loss — can emerge up to 10 years before a diagnosis.

Moreover, ethnicity or socioeconomic status were not found to be associated with Parkinson’s risk.

“This study confirms that many of the symptoms and early features of Parkinson’s can occur long before a diagnosis,” Alastair Noyce, PhD, the study’s lead investigator and a researcher at Queen Mary University of London, said in a university press release.

“We’re hoping to identify people at high risk of Parkinson’s even before obvious symptoms appear — which means that we could do more than just improve quality of life for patients, and perhaps be in the position to slow down or cure Parkinson’s in the future,” Noyce said.

Importantly, this study also identified hearing loss and seizures as early symptoms of Parkinson’s disease.

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The study, “Assessment of Risk Factors and Early Presentations of Parkinson Disease in Primary Care in a Diverse UK Population,” was published in JAMA Neurology.

Previous studies have identified risk factors and early signs of Parkinson’s disease. But these investigations were largely focused on affluent, white populations, with minority groups and individuals from low-income households remaining widely underrepresented.

“To allow us to get a full picture of the condition we need to ensure research is inclusive and represents all those affected,” said Cristina Simonet, MD, a PhD student at Queen Mary and the study’s lead author.

To address such discrepancies in the research to date, the team now analyzed primary healthcare records of 1,010,578 people living in East London between 1990 and 2018 — 1,055 of whom were diagnosed with Parkinson’s and 1,009,523 who served as controls. Of note, East London is one of the most ethnically diverse areas in the U.K., with high levels of economic deprivation.

In the Parkinson’s group, 15.7% of participants were Black, 19.7% South Asian, 50.9% White, and 8.3% other, which was similar to the non-Parkinson’s (control) group.

In terms of socioeconomic status, while more than 80% of those in the Parkinson’s group were in the lowest two-fifths of the population, economic deprivation was not significantly associated with Parkinson’s risk, nor was ethnicity.

“To our knowledge, this is the first study focusing on the prediagnostic phase of [Parkinson’s] in such a diverse population with universal access to health care,” the researchers wrote.

Several early symptoms of Parkinson’s emerged up to 10 years prior to a diagnosis, the study found.

Epilepsy and hearing loss — two newly identified risk factors — were significantly associated with Parkinson’s, and were among the symptoms that started in the decade before many patients were diagnosed. More research is needed to understand the relationship between symptoms such as seizure disorders and hearing problems and Parkinson’s disease, the team noted.

Other known Parkinson’s symptoms also appeared well before a diagnosis, the study found. Tremors were identified up to 10 years in advance, and cognitive signs emerged up to five years before a diagnosis.

“It is not a case of screening for asymptomatic disease but correctly identifying the underlying cause in patients who are presenting with symptoms and may seek timely onward referral,” the researchers wrote.

The association between cognitive symptoms and Parkinson’s was stronger than has been observed in previous studies, which could be related to a more diverse study population, according to the researchers. Previous reports noted that Black Parkinson’s patients are more likely to have cognitive impairment, which could in part explain the strong association.

Having type 2 diabetes, hypertension, or being underweight all were linked to a Parkinson’s diagnosis — as had been previously reported.

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Other previously identified early symptoms of Parkinson’s, including constipation, fatigue, insomnia, and sexual dysfunction, were not considered risk factors in this study. The researchers noted that these symptoms may still have been present, but minorities and lower-income groups may be more resilient or less likely to consult primary care physicians about them, making them thus underreported.

Some evidence suggests that ethnic minority groups may show atypical disease symptoms, which could lead to a misdiagnosis. This study is limited by the fact that Parkinson’s could have been underdiagnosed in this diverse study population, according to the team.

Nonetheless, the findings overall highlight early signs of Parkinson’s that could be used to accelerate a diagnosis.

“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 and doctors can act early to help manage the condition,” said Simonet.

The researchers emphasized that the greatest strength of the study was its large, diverse patient population.

“Parkinson’s affects everyone, regardless of race or social background, but research has often failed to represent the diversity of the community,” said Shafaq Hussain-Ali, a Parkinson’s patient and a member of the Parkinson’s UK Race Equality Steering Group.

“This research … helps address the many unknowns regarding how the condition affects people from under-represented groups. It means that life-changing new treatments can be developed that will benefit everyone with the condition,” said Hussain-Ali, who is of Pakistani Punjabi descent.

The study was performed as a part of PREDICT-PD, a large research project funded by Parkinson’s UK that seeks to identify people at high risk for Parkinson’s. The project is seeking 10,000 people, ages 60–80, who do not have Parkinson’s to complete a set of online screening tests. Interested individuals can register here.