Progressive Supranuclear Palsy (PSP)

Progressive supranuclear palsy (PSP) is an adult-onset, neurological disease that impacts movement, thinking, speech and vision. PSP is commonly referred to as an “atypical parkinsonism” because of its overlap of certain symptoms with Parkinson’s disease. However, it often progresses quite differently than Parkinson’s disease, and it shares similar pathology to Alzheimer’s and frontotemporal dementia.


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Quick Facts of PSP:

  • Progressive supranuclear palsy (PSP) is a rare neurodegenerative disorder that has no known cause or cure. 
  • It affects brain cells that control balance and coordination, eye movement, speech, swallowing and thinking.
  • On average, symptoms begin in the early 60’s, but may start as early as in the 40’s. 
  • PSP is slightly more common in men than women, but it has no known geographical, occupational, or racial preference. 

Symptoms of PSP include:

  • Loss of balance 
  • Changes in personality 
  • Weakness of eye movements, especially in the downward direction 
  • Weakened movements of the mouth, tongue, and throat 
  • Slurred speech 
  • Difficulty swallowing 

Prevalence

PSP is considered rare, affecting 6-10 individuals per 100,000, with about 30,000 cases in the United States. These numbers are likely underestimates due to frequent misdiagnosis of Parkinson’s disease or frontotemporal dementia. 

In comparison, about 1 million people in the U.S. have Parkinson’s disease, and about 7 million have Alzheimer’s disease. PSP is slightly more common than ALS (Lou Gehrig’s disease), but ALS is more widely known, easier to diagnose and often affects younger people.

PSP and Parkinson's Disease: 

PSP is sometimes called an “atypical parkinsonism” because of its overlap with some Parkinson’s disease symptoms. However, PSP and Parkinson's have their own unique set of symptoms and disease progression because they have different underlying causes. PSP symptoms are more similar to those associated with Alzheimer's disease and frontotemporal dementia

Parkinson's and PSP both tend to cause issues balance, stiffness, slowness and clumsiness. But even within these similar symptoms, they tend to differ. For instance, while tremor is a characteristic symptom for people with Parkinson's disease, people with PSP do not tend to experience tremor. In addition, when experiencing a fall, people with PSP tend to fall backwards, while people with Parkinson's tend to fall forwards. 

PSP also progresses more quickly than Parkinson's disease. More than 50% of people with PSP are initially misdiagnosed with Parkinson’s disease. Healthcare professionals usually begin to rethink the diagnosis when symptoms progress faster than expected or when typical Parkinson’s medications aren’t working.  

Receiving a PSP diagnosis can be challenging and frustrating. Even for those not initially misdiagnosed, the process can be lengthy because many healthcare providers are unfamiliar with the disease. As a result, it can take a long time for people to receive an accurate diagnosis.   

What is PSP?


Progressive supranuclear palsy is a disease that affects movement, thinking, speech and vision. It is called supranuclear palsy because "supranuclear" is the area of the brain that is affected and "palsy" means weakness or paralysis of a body part.

Common symptoms of PSP include: 

  • Issues with balance and walking
  • Frequent falls
  • Changes to vision
  • Difficulty with speech
  • Early forgetfulness
  • Personality changes
  • Loss of interest in activities
  • Impulsivity
  • Increased irritability 

While these are some common symptoms that people first experience with the diagnosis, each person with PSP will experience the disease differently. Not everyone who has PSP will have all of these symptoms and no two people with PSP will have the same set or severity of symptoms.

At this time, there is no specific test to diagnose PSP.

To diagnose PSP, a neurologist will gather a person’s medical history, including neurological symptoms, when they started, and how they impact the person’s everyday functioning. They will also perform a physical examination where they will evaluate how a person walks, speaks, and moves their eyes, feet and hands.

Neurologists will often refer to magnetic resonance imaging (MRI) to look for changes in the brain. On the MRI, there may be a noticeable atrophy found in the midbrain that resembles a hummingbird. The “hummingbird sign” on a MRI (sometimes called the “penguin sign”) can help to support a clinical diagnosis of PSP. A neurologist may decide to use other tests like blood tests, a neuropsychological evaluation, a DaTscan or positron emission tomography (PET) scan. These tests can help confirm a diagnosis of PSP or help rule out other causes of symptoms.

In some cases, a neurologist will gauge how someone responds to medications for Parkinson’s disease, which can also help a neurologist make a diagnosis of PSP.

Many people with PSP face a long and confusing diagnosis journey, including a number of tests, specialists, and diagnoses. It is our hope that better awareness of PSP, especially within the medical community, will lead to earlier and more accurate diagnosis.

Like Parkinson's disease, PSP is considered a movement disorder. This means that it features problems with movement and coordination. These symptoms often present as issues with balance, stiffness, coordination and slowness. Because of these symptoms, falls are a major concern for people with PSP. Occupational and physical therapists can help create individualized strategies to help with movement difficult and adapt to daily tasks. It is recommended to see an occupational or physical therapist that specializes in movement disorders if possible. 

Freezing of gait: The involuntary and temporary inability to move the legs and feet. This can happen at any time, but is most common when turning a corner or crossing through a doorway. 

Slowed movements: Involuntary slowness of movement can be felt in the feet, legs, torso and neck, arms and hands. 

Postural instability: Changes to the usual alignment of the body. This can be uncomfortable and also throw balance off.  

Rigidity: Muscles stiffen and create resistance to movement. This can make manual tasks more difficult, and can make it harder to regain balance, potentially causing falls. 

Dystonia: The contraction of muscles across legs, trunk and torso, arms, hands and feet. Some people with PSP might also experience these muscle contractions in the face.

Apraxia: The loss of the ability to carry out intentional movements. In PSP, this most commonly seen in speech and in the eyes. People with PSP might have a difficult time saying what they are thinking, which can feel frustrating to the person trying to speak. In apraxia of the eyes, people are not as able to control their eyelid movements and might experience a forceful closing of the eyes. 

As a reminder, no person with PSP will experience all of these symptoms, and each person will have their own severity of symptoms. There are many symptom management options and adaptive techniques for these symptoms, even as the disease progresses. 

Changes to vision can be an early symptom of PSP or a symptom that develops a few years after onset of symptoms. A neurologist or a neuropthomologist can help evaluate changes in eye function or vision. It's important to remember that not everyone with PSP will have all of these visual symptoms, and that symptoms vary by individual and in severity. 

Moving the eyes up and down: The most common and characteristic eye movement problem in PSP is an impaired ability to move the eyes up or down, known as eye movement apraxia. This is a symptom that is unique to PSP and distinguishes it from Parkinson's and general aging. Difficulty looking up and down can interfere with many daily activities, such as looking down at a plate while eating, descending a flight of stairs or stepping onto curbs. 

Jerky eye movements: PSP can cause the eyes to move in square, wavy jerks. These are rapid, involuntary, right-to-left movements that interfere with the ability to precisely aim the eyes at a target and make large movements of the eyes across the field of vision to become jerky rather than smooth. This can make reading or maintaining eye contact during conversation difficult. 

Double vision: Many people with PSP report double vision, which can look like two images of one object or the images may overlap. This can be an early symptom of PSP and can be helped with prism glasses or prism stickers. 

Abnormal eyelid movement: There are different types of abnormal eyelid movements that people with PSP can experience.

  • Involuntary closure of the eyelids: Known as blepharospasm, this can be either a forceful and involuntary eyelid closure that lasts a few seconds or minutes, or a difficulty initiating the opening of the eyelids. 
  • Difficulty closing the eyelids or blinking: While most people blink about 15 to 25 blinks per minute, people with PSP tend to blink only about 3 to 4 times per minute. This can allow the eyes to become dry. Dry eyes can lead to blurred vision, production of extra tears, or a sensitivity to light called photophobia.

Treatment options: A neurologist or a neurophthalmologist can help provide treatment options for individual syptmoms. Examples of common treatments are artificial tears for dry eyes, prism glasses or prism stickers for double vision and Botox injections or eyelid crutches for forced eyelid closure. Occupational therapists can also provide recommendations for adaptations related to vision that can make daily life easier and the home environment safer.

The general area of the brain that is affected by PSP controls movements of the mouth, tongue and throat.

PSP can cause speech to have:

  • An irregular, explosive, or rubber band quality (called spastic speech)
  • A slurred, drunken quality (called ataxic speech)

These changes to speech and voice can be coupled with difficulty getting out thoughts or finding words, making communication quite challenging for many people with PSP. It can be helpful to work with a speech-language pathologist, especially one who is specialized in Parkinson’s disease and related disorders, to learn exercises and strategies to help people with PSP continue to communicate as much as possible.

PSP affects swallowing by causing weakness and incoordination of throat muscles. This can make it more difficult to swallow, which increases the risk of food or liquids going into the lungs, called aspiration. In some cases, aspiration can lead to pneumonia. Swallowing issues also make it more difficult for people to eat and drink, and can cause involuntary dehydration or weight loss. 

Changes to swallowing function can occur early in PSP. Signs of swallowing dysfunction can include:

  • Coughing on thin liquids or more particulate foods, such as salads or dry cereal
  • Often having the sensation of food being caught in the throat
  • Having watery-sounding voice
  • Choking often
  • Recurrent lung infections
  • Frequent runny nose 
  • Sometimes people with PSP can eat more impulsively, including large bites or very quickly, which can also increase risk with swallowing

Your doctor may recommend regular examinations of your swallowing function to make sure food and liquid are going down the right way. Additionally, speech-language pathologists can help assess swallowing function as well as provide recommendations for diet and lifestyle modifications and exercises for the throat in order to make swallowing easier and safer.

There are different ways that PSP can affect cognition, and in different levels of severity. 

For many people, the initial concern is about developing dementia. To break it down, dementia is a term that refers to the loss of cognitive functioning to the extend that it impacts a person's daily life. There are different types and causes of dementia. In Alzheimer's disease, the most common cause of dementia, cognitive impairment is mostly in the area of memory. However, this is not the only form of dementia and does not automatically mean that people with PSP or related diseases will develop issues with memory. People with PSP tend to instead develop issues with processing and organizing thoughts, planning, multitasking, keeping attention and world-finding. 

Common cognitive issues that people PSP might experience: 

Aphasia: This is a cognitive deficit affecting communication, including finding words, expressing thoughts, and understanding language. Different neurological conditions can cause aphasia. Some people with PSP can experience aphasia. The severity can vary greatly, and for some, it can be an early symptom of PSP.

Impulsivity, poor judgment, and lack of insight: People experiencing these might not be aware of what their physical abilities are and complete movements that they are unable to accomplish .Impulsivity coupled with imbalance is the primary reason that people with PSP fall. For example, someone may jump up from a chair quickly, thinking they do not need to wait for assistance or use a walker, and fall. 

Some people with PSP will experience impulsivity as something like compulsive shopping. Many families struggle with the decision to have the person with PSP is adamant they can still drive or do other things safely when it is apparent to others that they are unsafe. 

Apathy: This can cause people to have less motivation to partake in activities. Cognitive changes in PSP can lead to social withdrawal or irritability, especially when they make communicating thoughts and participating in conversations more difficult.

Communication: Even in later stages of PSP, a person can often still respond to a question with accuracy and detail, but because of slowed processing speed, it may take several seconds or minutes and great effort to get out a thought. People with PSP and families can ask people to be patient when communicating. It can also be helpful to work with a speech-language pathologist on strategies to compensate for and adapt to cognitive changes and make communication easier.

PSP is not considered a genetic disease, but certain genetic variants have been found in those who have PSP. 

Scientists have found different variants in the tau protein gene on chromosome 17 that are more common in people with PSP compared to the general population. 

One of the variants is called the H1 haplotype. About 95% of people with PSP have this variant on both of their copies of chromosome 17, while this is true for only about 60% of people without PSP. Because of this, scientists believe that the H1 haplotype is likely needed, but far from sufficient, to cause the disease. This suggests that the H1 haplotype is almost necessary, but not sufficient on its own, to cause PSP. Scientists don’t yet know exactly how this gene variant impacts brain cells. It might cause the brain to produce more tau protein than normal or change how the protein works.

A handful of other gene variants that are not on chromosome 17 have been found to be more common in people with PSP than in people without PSP. These genes help control a variety of critical processes inside of brain cells. More research is needed to identify how these insights can translate into possible PSP prevention and treatment.

Genetic differences and exposure to certain chemicals are being explored as possible causes, but there is not currently an answer to why tau misfolds or people get PSP. For someone who is personally impacted by PSP, we recognize that not knowing the cause can be extremely frustrating, confusing, and scary. Researchers and doctors are working hard to understand PSP and other related neurodegenerative diagnoses, and we hope their work will lead to more answers and treatment options soon.

Read about the CurePSP Genetics Program to find out how you can help researchers learn more about how genes affect PSP, CBD and MSA. 


The name of the disease includes the word “progressive” because, unfortunately, early symptoms get worse and new symptoms develop over time. 

View CurePSP's resource "Stages of Progressive Supranuclear Palsy" for a general outline of what to expect in the future. 

Stages of PSP

Disease Management: 

When living with a serious and progressive disease, it’s normal to experience sadness, uncertainty and fear about what the future may hold. These are normal emotions to process after receiving a life altering diagnosis — it requires a lot of emotional and physical energy to continually adapt to physical and mental changes! Like all feelings, these emotions are often temporary. However, when these normal emotions regularly interrupt your daily life and prevent you from participating in activities that you previously enjoyed, this could be a sign of a mental health issue. 

People with PSP tend to experience depression and anxiety, but the most common mental health and mood symptom for people with PSP is apathy. Impulsivity and personality changes can also occur with PSP. While these symptoms can be isolating and scary, there are some treatment options to consider. 

Possible medications for depression and anxiety for people with PSP: 

  • Selective serotonin reuptake inhibitors (SSRIs) 
  • Serotonin and norepinephrine reuptake inhibitors (SNRIs) 
  • Gabapentin
Warning: Tricyclic antidepressants (TCAs) are often used to treat insomnia, headaches and pain in the general population. However, for people with PSP, TCAs can impact cognitive function and should be avoided. For headache, topiramate can be considered instead.

Always speak with your neurologist before starting a mood medication. 

Non-drug methods for improving mood:

  • Mental health therapy
  • Cognitive behavioral therapy (CBT)
  • Exercise
  • A balanced diet
  • Socialization
  • Good sleeping habits
  • Music
  • Meditation 

Urgent mental health support options: 

  • National Suicide Prevention Lifeline: 1-800-273-8255 
  • Now: 988 Suicide & Crisis Lifeline, dial/text 988.  
  • The Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline: 1-800-662-4357
  • Crisis Text Line: Text HOME to 741741

A physical therapist (PT) helps people with movement symptoms they are experiencing. This typically looks like going through exercises during appointments that can help strengthen or correct movements that are important for balance and coordination and then continuing them at home. People with PSP should begin to see a physical therapist when they notice changes in balance or are having more difficulty getting around.  An occupational therapist (OT) helps people continue doing tasks and activities that prolong independence and help maintain a sense of joy and meaning in their lives. 

Reasons to see a physical therapist: 

  • To prevent falls
  • Issues with balance and walking
  • Frequent falls
  • Changes to vision
  • Difficulty with speech
  • Early forgetfulness
  • Personality changes
  • Loss of interest in activities
  • To improve walking, with or without walking aids
  • To increase safety when actively sitting or standing.
  • To teach care partners safer ways of helping with transfers and walking.  

An occupational therapist (OT) helps people continue doing tasks and activities that prolong independence and help maintain a sense of joy and meaning in their lives. 

Reasons to see an occupational therapist: 

  • To modify activities and hobbies so the person can still enjoy them, even if they can no longer do them as they once could.  
  • To teach care partners how to safely complete activities of daily living, transfers and other caregiving tasks.   
  • To discuss individualized needs for adaptive equipment and assistive devices like grab bars, weighted utensils or bed rails.  
  • To be evaluated for canes, walkers or wheelchairs. 
  • To find adaptations for activities of daily living that aren't as easy to do as they once were. This includes activities like showering, bathing eating or writing. 

A speech-language pathologist (SLP) works with people who are having issues with speech, swallowing and language. Their goals are to improve and prolong communication skills, assess and help adapt to swallowing changes. 

Reasons to See a Speech-Language Pathologist: 

  • To provide techniques that encourage good communication, verbally and non-verbally. 
  • To learn about local and virtual programs that can help with speech symptoms. 
  • To assess memory and thinking issues, and make recommendations for adaptations. 
  • To evaluate swallowing symptom progression.
  • To evaluate speech symptom progression.
  • To teach adaptive techniques for eating and swallowing to keep the person safe. 
  • To prevent aspiration of liquids and food into the lungs. 

A feeding tube can be a safe and helpful option for people with PSP who are experiencing difficulties with swallowing. A feeding tube can be considered when someone is no longer able to take in necessary amounts of nutrition and calories by eating or drinking. They can prevent unnecessary weight loss and decreases risk of breathing in food or drink, known as aspiration. 

Getting a feeding tube placed means different things to different people, and there is no one right answer to whether or not someone should get on placed. Take the time to consider whether or not a feeding tube is right for you, before you need it. A feeding tube may get placed in some cases of emergency hospitalization, and if this is not a desire of yours, then be sure to state that in any advance directives. 

How is a feeding tube placed? Feeding tube placement is a surgical procedure done by a gastroenterologist (GI). The patient can be awake, but sedated and it is often an outpatient procedure.  

How is a feeding tube used? Formula or pureed food is fed through the feeding tube into the digestive system through either a syringe or a feeding bag. There are many store-bought formulas available that provide necessary amounts of nutrition and calories. There is also the choice to make food at home using a blender. Some people choose to feed with both formula and pureed food. Water can also be given through the feeding tube, both for hydration and to keep the feeding tube clear of debris and blockages. 

In some cases, and only if discussed with the healthcare team, medication can be given through the feeding tube.

Receiving a PSP diagnosis is a long and confusing journey for many people. It is very common to have initially received a Parkinson’s disease diagnosis prior to a PSP diagnosis because of the similarities in early symptoms. Because of this, many people who received a misdiagnosis of Parkinson’s had been told that carbidopa/levodopa can help alleviate slowness, stiffness and balance problems.  

Carbidopa/levodopa helps increase the effect of dopamine in the brain. While it tends to work fairly well for people with Parkinson’s, it does not directly translate to the movement symptoms in PSP. While the movement symptoms in Parkinson’s disease are caused by a lack of dopamine in the brain, PSP is not as directly related to dopamine levels and thus does not respond as well to the medication.  

People with the PSP-Richardson's Syndrome or PSP-Parkinsonism subtypes might respond slightly to these medications, but only for a few years before the effects wear off. When a neurologist prescribes carbidopa/levodopa to a person with PSP, it is recommended that they receive a standard form of the drug, rather than the controlled- or extended-release version of the medication. People with PSP might need a high dose of the drug and should be closely monitored by the healthcare team to watch for signs of cognitive issues or dizziness. 

Other Parkinson’s medications and their possible effect on PSP symptoms:  

Entacapone (Stalevo): Taken in conjunction with carbidopa/levodopa, entacapone slows down the rate at which dopamine is broken down. This will only have an effect for people whose symptoms are responding to carbidopa/levodopa.   

Dopamine receptor agonists: Rarely has any benefit for those with PSP and can even cause hallucinations and confusion, excessive involuntary movements, dizziness and nausea. 

Amantadine: This might have some benefit with gait issues, even if carbidopa/levodopa did not. Its benefit does not usually last more than a few months, but can be useful for a short period. For people with PSP, the dosage should not be larger than 200mg per day.  

Cholinesterase inhibitors: This class of medications is used to help people with Parkinson’s who are experiencing dementia and cognitive function. Most of these medications have no benefit in PSP, but rivastigmine (Exelon) might have a very small benefit in some people with PSP.  

Building a support team around you is foundational to quality of care and life with PSP. Your support team may consist of your partner, family, friends, support group, religious community, healthcare team, professional care, and others—people who care about you and show up for you.

When living with a chronic and progressive diagnosis, it is important to find the right medical team to support your needs with PSP over time. PSP needs to be managed by a neurologist. This could be a general neurologist, but, if available in your area, you may also choose to work with a neurologist who has gone through specific training in movement disorders or behavioral/cognitive neurology. Rehabilitation therapists (physical, occupational, and speech therapists) and clinical social workers also play important roles in the care of PSP. You may also benefit from adding other specialists to your team as symptoms and needs arise. These may include a urologist, sleep specialist, neuro-ophthalmologist, and palliative care specialist. Taking care of your emotional health, whether as a person diagnosed with PSP or as a carepartner, is also a priority, and working with a mental health professional to process the experience, foster coping skills, or address other emotional needs can be exceptionally beneficial. When building your care team, it is important you have providers that you have chemistry with and that you trust, and for you to know that you have the right and ability to change your providers if needed.

Completing health care advance directives is an excellent tool for sharing your wishes regarding care with your support team. Health care advance directives address topics such as how aggressive your medical care should be (for example, whether you would want a feeding tube or a machine for breathing, if the need arose) and how you define quality of life. These directives should be completed with your family and your doctor and should be reviewed at least annually in case your wishes change.

Many people living with PSP consider and explore professional care services, such as in-home care, adult day care, or long-term care, depending on their care needs and situation. These services can provide additional layers of support, including companionship or hands-on help for the person with PSP and assistance and respite for the family.

Additionally, there can be great value in connecting with other people affected by the same diagnosis as you and your family, through support groups or peer supporters. It can feel validating and uplifting to hear the experiences and insights on how others adjust to life with PSP. You can exchange helpful tips on ways to cope and adapt physically and psychologically with the diagnosis. CurePSP offers a variety of support groups for people affected by PSP. There are also many more for atypical parkinsonism (which can include PSP and other diseases, such as corticobasal degeneration and multiple system atrophy) in the United States and other countries. Visit www.psp.org/ineedsupport/supportgroups for a list of regional support groups as well as virtual, national and international support groups facilitated by or in collaboration with CurePSP. Additionally, many local Parkinson’s disease or frontotemporal dementia support groups welcome members with PSP. If you may be interested in starting your own PSP support group, contact CurePSP to learn more and for help in getting started. Additionally, CurePSP offers a peer support network, family conferences, and educational webinars where you can learn about PSP and connect to the community. We know that a diagnosis of PSP can bring up many emotions, changes, and considerations. No matter how you find support, please remember that you do not have to navigate the PSP journey alone.

Science and Research


The direct cause of PSP is not fully understood. However, we do know that it has to do with the clumps of a protein called “tau”. Tau is a normal protein found in brain cells and is currently thought to help maintain the microtubules, which are stiff rods that function as the brain cells’ internal transportation and skeletal system. In PSP, the tau seems to become abnormally folded, which causes it to stick together and become stuck inside the cell. In brains with PSP, the areas of the brain that have cells with tau inside of them show neuron impairment and neuronal death. The clumps’ technical name is neurofibrillary tangles. Alzheimer’s disease and frontotemporal dementia also involve misfolding of the tau protein.


There is important research being done to look for genetic and environmental contributors to the cause of PSP, as well as research on tests that can lead to more accurate diagnosis and improved care of PSP. Many people with PSP find that participation in research is a meaningful way to help doctors and scientists understand, diagnose and treat PSP and related diseases. Additionally, participants in clinical trials may benefit from a new treatment that is not generally available and may receive detailed care and attention that is not part of routine medical care.

CurePSP Genetics Program: In collaboration with Massachusetts General Hospital, the National Institutes of Health and Indiana University, CurePSP is hosting a program with the aim of collecting genetic data from those with a PSP, CBD or MSA diagnosis. Get involved at psp.org/genetic-program. 

Clinical trials: In the United States, clinical trials are listed on a website maintained by the National Institutes of Health, www.clinicaltrials.gov. You can enter “progressive supranuclear palsy” into the search box. You can also ask your neurologist if they are aware of studies in PSP or consult curepsp.org for that information.

Brain Donation: Donating your brain to science can be a powerful contribution to the understanding of PSP and other neurodegenerative conditions. Each donated brain is also evaluated by a trained neuropathologist to confirm that the diagnosis of PSP was correct. Setting up brain donation needs to occur early, ideally months or even years prior to someone passing away. Visit www.psp. org/ineedsupport/braindonation to learn about CurePSP’s Brain Donation Assistance Program.

Building Partnerships: CurePSP is working hard to build partnerships with pharmaceutical and biotechnology companies to develop interest and funding for the study of PSP and related diseases. 

Funding Research: Additionally, CurePSP funds research through various grant programs and supports collaborative research projects through its growing CurePSP Centers of Care network of medical centers across the United States and Canada.

What are the subtypes of PSP? 

Every person with PSP has their own unique set of symptoms and challenges. However, over time, researchers have found ten categories of symptoms in PSP. These categories are known as “subtypes.”  

Subtypes of PSP happen because of small variations in the ways in which a person’s brain is affected by the accumulation and misfolding of the tau protein. When giving a diagnosis of PSP, a neurologist might specify the subtype they think the person has, or they might simply diagnose them with PSP.  

The two most common types of PSP are PSP-Richardson's Syndrome (PSP-RS) and PSP-Parkinsonsim (PSP-P). However, there are cases where people are diagnosed with other subtypes. 

Although it’s known that PSP-RS is the most common, it’s difficult to estimate how many people with PSP have which subtype. It’s hard to know because: 

  • Statistics on PSP often exclude people who are unable to visit research insinuations due to barriers like cost and location.
  • Many studies and trials focus exclusively on PSP-RS, overlooking other subtypes.
  • Misdiagnosis of something other than PSP prevents many eligible patients from participating in clinical trials. 
  • Most cases of PSP tend to resemble PSP-RS as the disease progresses, making it hard to identify subtypes if they are not noted early. 
  • Clear clinical criteria for diagnosing PSP subtypes is not currently available. 

The most common initial symptom of PSP-RS is unexplained falls, but as the disease progresses, people might start to experience symptoms of other subtypes. Other common symptoms are issues with thinking and planning, controlling actions and speech, moving eyes up and down (supranuclear gaze palsy) and controlling the eyelids, swallowing, difficulty moving at a normal pace, ability to control the bladder and sleeping issues.  

PSP-Parkinsonism is the second most common subtype of PSP. Compared to PSP-RS, it has more asymmetry (one-sidedness), tremor and slowness. Compared to other types of PSP, PSP-P responds better to Parkinsonism medications, like levodopa. People with PSP-P tend to have fewer issues with thinking, behavior, balance and eye movement. It typically progresses the slowest of all the subtypes, averaging about nine years of survival after the first symptoms.  

PSP-P is often originally diagnosed as Parkinson’s disease because of the symptom similarities and the tendency for better and early responsiveness to Parkinson’s medications. It’s usually only when symptoms progress faster than expected that the medical team begins to rethink the Parkinson’s diagnosis. 

The main symptom of PSP-PGF is no longer being able to maintain an ongoing gait, or difficulty continuing walking after a step or two. This is especially true after pausing, turning or entering a doorway threshold. As the disease progresses, people with PSP-PGF usually can’t initiate walking at all. 

People with PSP-PGF may struggle with small handwriting and rapid speech. People that have issues with progressive gait freezing without other neurological symptoms are likely to eventually develop PSP.  

PSP-SL is a composite category, meaning that it is made up of other, smaller classifications that cover speech and language. Both subtypes in this category can have aphasia as a symptom. Aphasia is when someone has trouble mentally finding words, expressing thoughts or understanding language.   

People with PSP-SL experience a specific kind of aphasia, known as Primary Progressive Aphasia (PPA). This means that aphasia is caused by a progressive issue in the brain, rather than something like a stroke or a head injury. The two types of Progressive Aphasia in the PSP-SL category are:  

PSP-Nonfluent/Agrammatic variant of Primary Progressive Aphasia (PSP-nfaPPA): speech is halting with poor grammar and there is difficulty with syntax (sentence structure) and pronunciation. Comprehension and ability to name items and people are not affected.  

PSP-Semantic-Variant Primary Progressive Aphasia (PSP-svPPA): there is difficulty naming items and people but no issue with using proper grammar or syntax.  

PSP-CBS is highly asymmetric, meaning symptoms are usually only on one side of the body, or at least more prominent on one side. Symptoms tend to be rigidity, slowed movement and loss of skilled movement (called apraxia). It also features asymmetric fixed postures (called dystonia), weakness, abnormal reflexes (pyramidal findings) and small, rapid and irregular movements (known as myoclonus).  

People with PSP-CBS may also have a loss of visual perception, ability to identify familiar objects by touch or understanding where their body or limbs are in space. Aphasia, or difficulty understanding and pronouncing language, can sometimes happen.  

People with PSP-CBS have fewer issues with eyes, and less postural instability and cognitive loss than PSP-RS. CBS is a disease that is closely related to PSP, and it is sometimes given as a diagnosis by itself. 

PSP-F features some behavioral challenges, such as disinhibition, irritability, apathy and loss of empathy for others. It also is known for greater impairment in executive functions like maintaining attention, ability to follow instructions, changing tasks on command or stopping a behavior when attempting to.  

These specific cognitive and behavioral issues can be also found in PSP-RS but are usually milder than in PSP-F and only show up later in the disease. 

One of the main symptoms of PSP-RS is vision and eye symptoms. For people with PSP-OM, however, vision and eye trouble are one of the only features they experience. People with PSP-OM may have difficulty looking up or down, trouble tracking moving items with the eyes and other ocular problems. Issues with the eyes can sometimes cause falls in people with PSP-OM, because of problems in perception and sight.  

Another main symptom of PSP-RS is postural instability, which is trouble with balance, maintaining an upright posture and trouble walking. People with PSP-PI experience these parts of PSP-RS and might experience frequent falls due to these issues. Similarly to PSP-OM, this subtype features little else of the classic PSP-RS.  

PSP-PLS is a subtype of amyotrophic lateral sclerosis, known as ALS or Lou Gehrig disease. It can be difficult to tell ALS apart from PSP-PLS, but PSP-PLS is highly asymmetric and is similar to corticobasal syndrome (PSP-CBS). However, PSP-PLS rarely has the sensory loss, dystonia or the small and irregular movements that CBS is known for.  

The cerebellum is the area of the brain that’s located at the back of the head and helps control voluntary movement. PSP-C can cause balance and coordination problems and issues with vision and fine motor movements. Those with PSP-C have a lurching walk of PSP-RS (sometimes described as appearing as though the person is intoxicated), jerking movements of the eyes and slurred speech.  

It can be hard to tell PSP-C apart from PSP-RS while the person with the disease is still alive. When brain tissue is examined during autopsy, people with PSP-C are usually found to have shrunk cerebellums. 

For unclear reasons, this subtype is far more common in East Asia than elsewhere in the world. 

While there isn't currently a lot we know about PSP subtypes, there is much ongoing research around PSP subtypes. Some goals of this research are to: 

  • Understand why PSP-RS and other cortical subtypes progress faster than subcortical subtypes, which would lead to more effective treatments. 
  • Find better ways to diagnose and include people with PSP-RS subtypes in clinical trials. 

Regarding clinical trials only accepting those with PSP-RS, the reasons are because: 

  • Less common PSP subtypes may react differently to drugs and treatments due to a small molecular differences from PSP-RS. 
  • Because PSP-RS progresses more quickly than other subtypes, trials will have results in a shorter amount of time with fewer participants. 
  • PSP-RS is usually confirmed by autopsy, 
  • Most people who have early signs of PSP-RS are likely to be confirmed to have PSP at autopsy. However, with the other subtypes, there is a greater chance that people have other underlying conditions causing their symptoms, which could cloud the results of a drug study on PSP. 
  • Almost all PSP trials measure outcomes using the PSP Rating Scale, which was designed to only measure PSP-RS. Because it was not designed to measure subtypes other than PSP-RS, other subtypes could cloud the data. 


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