How Is Parkinson’s Disease Diagnosed?

Speculation about President Joe Biden’s health is rife after the president’s poor debate performance, marked by a stiff gait and soft voice, and muddled answers. Also fueling conjecture is reporting in the New York Times and elsewhere that, according to visitor logs, a neurologist who specializes in movement disorders like Parkinson’s disease has come to the White House eight times in the past eight months. 

The White House pushed back, releasing a letter from Dr. Kevin O’Connor, physician to the president, explaining that the specialist, Dr. Kevin Cannard, was at the residence in support of active duty service members assigned to White House operations, some of whom may have neurological issues related to their service. Cannard has only examined Biden during his annual physicals, according to the White House. The president, according to O’Connor’s letter and its account of details of Biden’s physical released in February, does not have symptoms consistent with "any cerebellar or other central neurological disorder, such as stroke, multiple sclerosis, Parkinson's or ascending lateral sclerosis."

Parkinson's is not always straightforward to spot. Here, experts (who are not involved in Biden's care) explain what people should know about how the disease typically presents and how it's diagnosed.

The varied signs and symptoms of Parkinson’s disease 

Dr. Michael Okun, director of the Fixel Institute for Neurological Diseases at the University of Florida and medical adviser to the Parkinson’s Foundation, says that Parkinson’s disease might be better called Parkinson’s diseases—plural—because the condition has many different causes and expressions.

“There are multiple causes for Parkinson’s and a lot of them have similar symptoms, but we tend to clump them together, because humans like to clump things—it’s easier to deal with,” he says.

For one thing, Okun explains, about 15% to 20% of Parkinson’s cases are associated with a genetic abnormality, and in those cases, patients are likelier to develop symptoms earlier—at age 50, or even 45 or 40. In cases that aren’t genetic, neurologists look at possible environmental causes. “We’ve been interested in pesticides, chemicals, and other things in the environment that might be triggering symptoms,” he says.

Whatever the causes, the brains of Parkinson’s patients generally start to show a deficit in three neurotransmitters: serotonin, dopamine, and acetylcholine. Those neurological changes don’t, at first, lead to the motor symptoms that are commonly associated with the disease. Rather, people may experience a loss of the sense of smell, constipation, and sleep disturbances known as REM sleep behavior disorder. In these cases, dreams may become so vivid that people act them out. “Let’s say you’re fighting off the bad guys,” Okun says. “You might be punching in your sleep, and that’s not a good thing for your bed partner.”

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Later symptoms start to involve emotional functions. Parkinson’s patients are at higher risk than other people of experiencing depression, anxiety, and apathy, and when anxiety in particular occurs for the first time later in life, a Parkinson’s screening might be warranted. “People who have new-onset anxiety over the age of 50 are at twice the risk of having Parkinson’s disease,” says Okun.

More common are the motor and cognitive deficits that most define the disease. People with Parkinson’s may become distracted or disorganized or find it difficult to plan or accomplish tasks. About 80% of people with the disease have a resting tremor in the hands—though that means that one out of five don’t have this signature symptom. Posture can suffer as well, and stiffness in the wrists and arms may be evident. Steps may become shuffling, and there can be an overall slowness, called bradykinesia. 

“When you have people tap their fingers or open or close their hands, there’s a certain slowness the neurologist is looking for,” says Okun. Speech can be affected too. “Sometimes people repeat syllables in the middle of speech,” Okun says. “The voice can become softer and softer and sometimes trail off.”

Other symptoms affect the face, with blinking becoming less frequent and facial muscles growing stiff or still—a condition called masked face. 

How Parkinson’s is diagnosed

In the early stages of Parkinson’s, an internist, family physician, or neurologist is often the first to make a diagnosis, according to the Parkinson’s Foundation. The most common symptoms that lead to a diagnosis are a resting tremor; stiffness or rigidity in the arms, legs, or trunk; or trouble with balance and falls. Magnetic resonance imaging (MRI) or a dopamine transport scan of the brain—in which a radioactive tracer that attaches itself to dopamine receptors is injected into the blood—can also help confirm the diagnosis. No doctor of any kind, of course, can diagnose Parkinson’s in someone without seeing and evaluating the person. When it comes to the president or any other public official or celebrity, Okun abides by the so-called Goldwater Rule—adopted by the American Psychiatric Association after hundreds of psychiatrists presumed, without an exam, to diagnose mental illness in Republican presidential nominee Barry Goldwater in 1964. 

“I was one of the physicians who cared for Muhammed Ali,” says Okun, “and we didn’t publish details of his medical record until we had permission of the family.”

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Still, Okun urges family members and others to follow the "see something, say something" guideline. "If you see somebody who's not blinking, if you see someone who has decreased facial expression, if you see someone who is rigid or still in the arms or shuffling or falling, get those folks to the right doctors," he says. "In Parkinson's disease you need a whole team."

Treatment options

There is no cure for Parkinson’s disease, but people with the condition are by no means without recourse. A dozen or so medications and medication cocktails exist, including levodopa, a dopamine replacement drug that helps ease physical symptoms. Also increasingly used are selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), which increase the availability of both neurotransmitters in the brain. 

“There are other drugs that go straight to the dopamine receptors and sort of tickle the receptors,” says Okun. “These are called dopamine agonists.” Increasingly popular is also deep-brain stimulation, in which a fine probe is threaded into the brain and adjusts its firing, similar to the way a pacemaker affects the heart.