Diagnosing Parkinson’s disease poses a challenge for doctors — not to mention patients — because there’s no specific test for the condition.
Making the call comes down to reviewing patients’ medical histories, looking at their symptoms and conducting a neurological and physical examination. Ultimately, doctors give patients a medication used to treat Parkinson’s. If they respond — and have the right symptoms — a doctor can diagnose the degenerative neuromuscular condition.
Dr. Melinda Burnett, a neurologist with the CHI Health Neurological Institute in Omaha, said studies indicate that even movement disorder specialists like her make the right call only 80% of the time. Symptoms vary from person-to-person, and a number of other illnesses produce similar ones.
Now she and a team led by Jee Yeon Hwang, an assistant professor of pharmacology and neuroscience with Creighton University School of Medicine, have begun an early-stage clinical study to look for tiny particles released by brain cells in patients’ blood. Their ultimate goal is to develop a blood test that could be used to diagnose Parkinson’s.
The particles, known as exosomes, contain certain proteins that build up in the brains of people with Parkinson’s, as well as small bits of RNA and other molecules.
Previously, Hwang said, scientists have found proteins carried by exosomes in cerebrospinal fluid, which surrounds the brain and spinal cord. But the fluid can only be obtained through a spinal tap.
Exosomes, however, are small enough to pass from the brain through the protective blood-brain barrier into the bloodstream, she said. Researchers want to try to isolate exosomes that originate in the central nervous system from blood samples — which they now have the tools to do — and see whether they can identify biological markers for the disease.
Burnett put it in layman’s terms: Exosomes “are little messengers that can slip through the defenses and cross the blood brain barrier.” Hwang, she said, “knows how to crack open these little Easter eggs and look inside.”
Identifying a biomarker could not only help researchers develop a test for the disease, Burnett said, but also could help them find an objective way to determine how quickly it’s progressing and even help speed the developments of new treatments.
Parkinson’s is frustrating for many patients because it creeps up on them, she said. Researchers suspect that the disease actually starts 10 to 20 years before patients show symptoms. Because of the lack of a test, some find it hard to accept the diagnosis.
“Having something objective, a positive test, would help people reach some closure and acceptance quicker, I would think,” Burnett said.
Nebraska is known to have a higher incidence of Parkinson’s diagnoses than many other states, she said. An average of 588 patients were diagnosed each year between 1997 and 2017, according to the Nebraska Parkinson’s Disease Registry.
National data from the Blue Cross Blue Shield Association in 2017 indicated that not only were Parkinson’s diagnoses increasing but also that prevalence was rising in younger adults, with 57 being the average age at diagnosis for people 64 and younger with commercial insurance. Burnett said that’s lower than the average age of 63 she learned in medical school.
The lack of a test, not to mention a cure, for Parkinson’s convinced David Sindelar to sign up for the study. A patient of Burnett’s, the Omaha resident, now 63, was diagnosed about four years ago.
He’s among 10 Parkinson’s patients already participating. The researchers are seeking at least 25 Parkinson’s patients for the pilot study and 50 people who don’t have the condition who will serve as controls.
“One thing I can do, having Parkinson’s already, is participate in studies like this,” Sindelar said.
Others interested in participating in the study can call the Creighton research office at 402-280-4032, which will connect them to an answering machine where they can leave their contact information.
Sindelar said his symptoms haven’t progressed significantly. He has a little shaking and a tendency to hunch, so he’s careful to make sure his posture is straight and erect when he goes for a walk.
He works full-time as a court clerk and acts in local theater productions, in recent years mostly with the Brigit St. Brigit Theatre Co.
By talking about his condition, he said, he feels he can serve as an example to the people who see him on stage.
David Sindelar, far left, of Omaha is participating in a CHI Health/Creighton University study seeking a biomarker that could lead to a blood test for Parkinson’s disease, which he was diagnosed with about four years ago. He’s active in local theater. In 2020, he was in the cast of “Incident at Vichy” at Brigit St. Brigit Theatre.