Progressive Supranuclear Palsy: Causes and Treatment

Progressive supranuclear palsy (PSP) is a rare neurological disorder affecting movement, coordination, and cognition. The misdiagnosis of Parkinson’s disease sometimes occurs due to its similar presentation. However, PSP has some specific differences, so awareness of the early presentation can alert someone to seek medical attention and advocate for early diagnosis and intervention.

A real-life example

Monica, age 65, presented to the memory clinic with her husband, Bill, for assessment by a geriatrician. As Monica walked down the hall with her walker, there were obvious signs of unstable gait. The nurse noted Monica's slurred speech and abnormal eye movements while taking a brief history and blood pressure for the assessment.

Monica seemed almost stroke-like to the nurse, but they noted the primary care provider ruled that out with a CT scan. Bill explained that Monica fell daily at home, and sometimes multiple times. Bill cared for Monica and was now unable to leave her home alone. Later, after a diagnosis of PSP, Monica declined further. Finally, Bill could no longer care for her at home and had to place her in a long-term care facility. Monica passed away roughly four years after her official diagnosis.

What is PSP?

Progressive supranuclear palsy (PSP) is a rare brain disorder affecting gait, speech, vision, and cognition. Most commonly, PSP occurs in adults over the age of 60 — affecting mostly men. Approximately 3–6 people in every 100,000 globally live with PSP, translating into 20,000 people currently diagnosed with the disorder in the US.

In 1964 scientists differentiated PSP from Parkinson’s disease (PD), which has a similar presentation but more distinctive features. One distinguishing feature between PSP and PD is that PSP progresses much faster.

What causes PSP?

The exact cause of PSP has yet to be fully understood. However, experts know there is a gradual deterioration in brain cells in people with PSP. This occurs in a specific part of the brain called the basal ganglia. Specifically, PSP affects the group of cells in the basal ganglia called substantia nigra, which produces dopamine. This brain area precisely controls smooth movement, balance, and cognitive functions. It seems there is an abnormal build of tau protein clumps deep into the substantia nigra, destroying nerve cells.

Unfortunately, PSP occurs sporadically without a known cause. While there doesn’t appear to be a confirmed genetic component, there have been rare cases when someone else “in the family” may have another documented illness having similar features to PSP.

There have been some rare cases where PSP results from mutations in the MAPT gene, which controls the production of the tau protein. For example, this mutation can cause the gene to encode improperly, causing increased tau production and disrupting nerve cells.

Symptoms of PSP

There are several symptoms that occur in progressive supranuclear palsy, which include:

• Problems with balance, gait, and coordination
• Increased falls
• Walking with a notable “stiffness” or head leaning backward
• Fluctuations in mood, such as emotional outbursts, anger, and crying
• Problems sleeping
• Depression
• Difficulty producing speech (dysarthria), slurred speech
• Difficulty swallowing (dysphagia), cough, and possible choking
• Difficulty with eye movements, blurred vision, or keeping eyes open
• Trouble holding a “gaze” on someone or something
• Increased forgetfulness, lack of insight, loss of interest
• Word finding difficulty
• Dementia

How is PSP diagnosed?

This is where the misdiagnosis of Parkinson’s may occur because, in the earlier stages, both conditions present with similar symptoms. However, sometimes changes may be seen on an MRI in some people affected by PSP.

The main differences between PSP and PD are that people with PSP stand straight and sometimes fall backward, and people with PD tend to bend forward. Additionally, people with PSP have eye movement difficulties, which are not noted in PD. Furthermore, people with PSP tend not to have tremors, which is prevalent in PD. However, the progression of PSP is more rapid than in people with PD.

PSP treatment options

There aren't effective treatments for PSP. Most medications only slightly reduce the symptoms. However, some medications have been shown to help manage the effects of the condition.

• Medications. Parkinson’s disease medications, such as Levodopa and ropinirole, are often trialed to manage movement. However, most people with PSP do not respond well or have a minimal response.
• Depression. This is a frequent problem with PSP, so SSRI (selective serotonin reuptake inhibitors) antidepressants may be beneficial.
• Physiotherapy. Various exercises may help with joint stiffness.
• Occupational therapy. OT is appropriate to assist with aids to maintain ADLs (activities of daily living) and provide a home safety assessment.
• Bifocal glasses. Special lenses called “prisms” may help a person with PSP, especially with the difficulty of “downward gaze.”
• Feeding tube. Because some people with PSP may have difficulty swallowing normal foods, they become choking hazards. Therefore, some people may require a feeding tube to receive special nutritional preparations.

What is the prognosis for PSP?

There is currently no cure for PSP. Because of the rapid progression, a person usually becomes entirely disabled within three to five years. The main risk due to swallowing difficulty is aspiration pneumonia (pneumonia caused by food or other object inhaled due to swallowing problems). This type of pneumonia is often the ultimate cause of death in someone with PSP. Preventing aspiration pneumonia may result in people with PSP being able to live past five years. However, due to their declining physical condition, they will likely need to be in a supported long-term care facility.

Research and clinical trials are ongoing, with updated diagnostic and treatment recommendations on the horizon. Some organizations provide support information, and the latest research on PSP at CUREPSP or National Organization for Rare Disorders.

Progressive supranuclear palsy is a rare neurological disorder with no known cure. Awareness of the signs and the specific differences between PSP and PD is essential for early diagnosis from your healthcare provider. While no specific treatment is available for PSP, management of symptoms and referral for home support will assist someone with the disorder in maintaining the quality of life and managing the symptoms as their overall condition declines.