Parkinsonism is a neurodegenerative disease that most people have heard of, and many have experienced in their own families. According to the Parkinson’s Foundation, about 1 million Americans have Parkinson’s disease (PD), and about 60,000 are newly diagnosed with it each year. The higher-than-usual reader response to my recent Parkinson’s disease blog posts attests to the incidence of the disease.
PD usually affects people over the age of 60—slightly more men than women. Actor Michael J. Fox is among the estimated 4 percent of PD patients who are diagnosed before the age of 50. Fox has been exemplary in publicly sharing details about his disease and in demonstrating by example that people with PD can work and live fruitful lives within their “new normal.”
If you would like more information about PD, please turn to the excellent Parkinson’s disease information page of the National Institute of Neurological Disorders and Stroke (NINDS) at the National Institutes of Health: https://www.ninds.nih.gov/Disorders/All-Disorders/Parkinsons-Disease-Information-Page. You can find much information online about PD.
Today, I’d like to tell you about another progressive and chronic movement disorder that is often misdiagnosed as Parkinson’s disease because its early symptoms are similar and neurologists rarely see it. You probably don’t know this disease. It’s called progressive supranuclear palsy, or PSP, and it affects an estimated 20,000 Americans, in total.
The disorder’s long name signifies that it worsens (progressive) with time—much quicker after onset than PD does—and causes weakness (palsy) by damaging certain part of the brain above (supra) nerve-cell clusters called nuclei (nuclear). These nuclei, in particular, control eye movements.
PSP was first described as a distinct brain disorder in 1964, when three scientists published an article distinguishing it from Parkinson’s disease. PSP is sometimes referred to as Steele-Richardson-Olszewski syndrome, in recognition of the clinical researchers who described it.*
According to the Maryland-based CUREPSP (Foundation for PSP/CBD and Related Brain Diseases), only about 4,000 of the 20,000 Americans presumed to have PSP know they have it. No diagnostic test exists for PSP
The Face of PSP: Dudley Moore
I first learned about PSP in 1999, when a very good friend of my parents, Dr. Tom Stevenson, died from the disorder at the age of 75.
Around the same time, gifted musician/composer, actor, and comic-sketch genius Dudley Moore revealed in a “20/20” interview with Barbara Walters that he was suffering from progressive supranuclear palsy. He wasn’t drinking excessively and behaving badly in public, as his movie character Arthur might have and as so many critics had speculated. He was sick, very sick.
Unfortunately, distinguishing PSP from Parkinson’s disease does not give you a better prognosis, just an understanding of what you’re experiencing.
I will never forget the clearly angry Moore’s struggle to walk and speak during that brave interview with Walters. A once-rakish personality, he was truly a tragic figure, his mind intact—which is not always the case with PSP—but “trapped,” as he said, in his degenerating body.
Moore died in 2002 at age 66. You may read a transcript of his “20/20” interview here: http://abcnews.go.com/2020/story?id=123930&page=1.
During years of mysterious failing health, Tom Stevenson, like Dudley Moore, had regressed from being unsteady on his feet and falling to being unable to walk. Speech and swallowing difficulties also had ensued, the latter posing the threat of choking. Pneumonia was the immediate cause of his death.
A number of physicians examined Stevenson during his decline and thought he had Parkinson’s disease, but Stevenson, a hematologist who spent most of his career at the Ohio State University College of Medicine, was not so sure.
Ironically, my parents’ friend had fully expected to die of a heart attack in his 40s, as his father and paternal uncle had before him. For decades, he scrupulously watched his diet and cholesterol, played tennis and golf, and was very fit.
But for Stevenson, PSP, too, was second-generational: It killed his mother. He didn’t know the cause of her death, however, until a few months before his own, when his mother’s neurologist examined him and told him.
Just last year, a good friend of mine told me that her 88-year-old father-in-law, who had been diagnosed with Parkinson’s disease about five years ago, had been re-diagnosed with PSP. He is now mobile only with a wheelchair and lives in a nursing home.
Symptoms of PSP
Early symptoms of progressive supranuclear palsy are similar to those of PD and include falling, difficulty in walking, imbalance, and slow movement. Both PSP and PD also cause stiffness and clumsiness.
But just as tremors, a hallmark of PD, are rare in PSP, PSP derives part of its name from a symptom that does not occur in PD: palsy of eye movements.
According to the NINDS, “[E]ye problems, in particular, slowness of eye movements, usually offer the first definitive clue that PSP is the proper diagnosis. Individuals affected by PSP especially have trouble voluntarily shifting their gaze vertically (i.e., downward and/or upward) and also can have trouble controlling their eyelids. This can lead to a need to move the head to look in different directions, involuntary closing of the eyes, prolonged or infrequent blinking, or difficulty in opening the eyes.”
A person with PSP may be unable to maintain eye contact during a conversation, notes the NINDS, giving off a false impression of disinterest or even hostility.
I never heard that Dr. Stevenson had eye problems–although he most likely did–just speech and swallowing problems, the latter of which impaired his ability to eat solid foods. According to the NINDS, PSP symptoms can vary considerably from person to person.
In distinguishing PSP from Parkinsonism, the NINDS says:
“People with PSP usually stand exceptionally straight or occasionally even tilt their heads backward (and tend to fall backward). This is termed ‘axial rigidity.’ Those with Parkinson’s disease usually bend forward. Problems with speech and swallowing are much more common and severe in PSP than in Parkinson’s disease, and tend to show up earlier in the course of the disease.”
People with PSP often show alterations of mood and behavior, including depression and apathy, and some exhibit changes in judgment and other executive functions, such as problem solving.
According to the NINDS, PSP patients “may lose interest in ordinary pleasurable activities or show increased irritability and forgetfulness. Individuals may suddenly laugh or cry for no apparent reason, they may be apathetic, or they may have occasional angry outbursts, also for no apparent reason.”
While it is common for PSP to be misdiagnosed as PD in the early stages of the disease, all neurologists should be able to distinguish PSP from PD in PSP’s later stages.
Unfortunately, memory problems and personality changes brought on by PSP may lead some physicians, who do not specialize in neurological disorders, to mistake PSP for depression or even a form of dementia. The key to a correct diagnosis, says the NINDS, is identifying early gait instability (falling while walking), difficulty with eye movements, and speech and swallowing abnormalities, while also RULING OUT other similar disorders.
Incurable brain disease
Just like Parkinson’s disease, the underlying cause of PSP—why a normal brain becomes diseased—is not known. In a very few cases, however, the disease has been shown to result from mutations in a particular gene.
PSP occurs with cell deterioration in a few small and important places in the base of the brain, including the substantia nigra, which is implicated in Parkinsonism. These degenerating cells contain an abnormal amount of a normal protein called tau.
In contrast, the affected brain cells of people with PD show an accumulation of a protein known as alpha-synuclein, not tau.
The clumping of tau in nerve cells causes the cells to work improperly and eventually to die. The toxic tau disrupts signal pathways inside the cells.
PSP is in a group of disorders called the tauopathies, which also includes Alzheimer’s disease and some forms of frontotemporal degeneration. As noted above, some PSP sufferers, including my friend’s father-in-law, experience dementia-like symptoms
As is the case with Parkinson’s disease, there is no cure for PSP, which generally runs its course in three to five years. In some patients, balance, stiffness, and other motor symptoms of PSP may respond to antiparkinsonian agents, but the effect is usually minimal and short-lasting.
I join CUREPSP in hoping that research will soon lead to a cure for PSP. For more information about this rare neurodegenerative disorder, please see CUREPSP at https://www.psp.org/iwanttolearn/progressive-supranuclear-palsy/#page-section-progressive-supranuclear-palsy, or the NINDS’s website at https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Progressive-Supranuclear-Palsy-Fact-Sheet.
*Steele, Richardson, and Olszewski, “Progressive Supranuclear Palsy. A Heterogeneous Degeneration Involving the Brain Stem, Basal Ganglia, and Cerebellum With Vertical Gaze and Pseudobulbar Palsy, Nuchal Dystonia, and Dementia,” Archives of Neurology 10 (1964): 333-59.