Progressive Supranuclear Palsy: An Atypical Parkinsonian Syndrome
Progressive supranuclear palsy (PSP) is not Parkinson's disease (PD), but is a Parkinsonian-like syndrome. PSP is a rare brain disorder that causes serious and progressive problems with gait and balance, as well as eye movement and thinking problems. It gets its name because it begins slowly and continues to get worse (progressive), it causes weakness (palsy) by damaging certain parts of the brain structures called nuclei that control eye movements (supranuclear).1
Like Parkinson's, PSP has no known cause, no cure and is not life-threatening. Neither has a diagnostic lab test and both can be characterized as movement disorders. Both PSP and PD tend to present around age 60. PSP can cause complications, like pneumonia, that can reduce life expectancy. Unlike PD, PSP has no effective treatment. PSP is considered rare, affecting around 20,000 Americans, while PD is more common with over 50,000 new cases diagnosed each year. Many symptoms of PSP are also identifiable in people with Parkinson's, resulting in PSP often being misdiagnosed as PD.2
Hallmarks of PSP
PSP affects balance, movement, gait, vision, speech, thinking, mood and behavior displays. PSP symptoms that are similar to those of PD include difficulties with balance, unexplained falls, and awkward gait. A classic early sign of PSP is visual disturbance - the inability to control the movement of the eyes. Changes in vision and control of the eyes can be diagnostic clues that differentiate PSP. The inability to move your eyes up and down or look a person in the eyes can create awkward interpersonal interactions.
Cognitive symptoms including changes in executive function, mood and behavior are also common in PSP. There can be losses of emotional stability characterized by sudden and uncontrollable bouts of laughter or crying which can result in embarrassing and inappropriate behavior in social or work situations.
What causes it?
First described in 1964 by three scientists, it has also been known by their names as Steele-Richardson-Olszewski syndrome. PSP is considered a sporadic neurodegenerative disease, one that develops by chance.3 Build up of the Tau protein in the brain causes cellular damage and thus affects the normal function of neurons. PSP is considered a tauopathy as is Alzheimer's and other frontotemporal brain disorders.
How is it managed?
There is neither a cure nor an effective treatment for PSP. Most symptoms don't respond to drug therapy. Some anti-parkinsonian medications like levodopa have been tried but therapeutic effects, if any, are generally short-lived.
Hallmarks of Parkinson's
Parkinson's disease is a chronic neurodegenerative disorder that is generally thought of as a motor disorder. Symptoms develop slowly over time and vary from person to person. The key motor characteristics are tremor, slowness of movement, frozen limbs and difficulty with gait. People with Parkinson's also experience changes in mood and behavior. Cognitive impairment can range from depression and anxiety, to psychosis. In fact, many find living with the non-motor changes of PD to be more difficult than the motor symptoms.
What causes the condition?
First described in 1917 by James Parkinson as the shaking palsy, PD is characterized by a loss of neurons in the substantia nigra portion of the brain. A buildup of the protein alpha-synuclein causes dopamine producing cells to fail and die. There is no known specific cause of PD but it is considered to be a combination of genetic and environmental factors just like PSP.
How is it managed?
Symptoms of PD develop over years. Dopamine replacement therapy is the first line treatment for Parkinson's. Since each case of Parkinson's is unique, there is no telling which symptoms may develop. There are 5 stages of Parkinson's and not everyone will progress through each stage.
New research is looking at gene mutations that could either cause the disease or be instrumental in directing the development of future specific therapies. PSP is being studied as part of the National Institute of Neurological Disorders and Stroke (NINDS) Parkinson's Disease Biomarkers Program.2 Improved brain imaging may also help with earlier and more accurate diagnoses, disease monitoring, and progression.
Research is also examining the gene-environmental interaction, the influence of the environment on the expression of genes resulting in disease susceptibility. Scientists are also evaluating symptoms that are now considered precursors to disease development. For example, some non-motor symptoms like the loss of the sense of smell and having difficulty sleeping may precede the development of motor symptoms in PD. As a way to detect both diseases earlier, the intent is to develop treatments that can slow or stop progression.
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