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What is Parkinson's disease?

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Emma Giles.

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  • leaf green style avatar for user Brooke
    Are symptoms like depression caused directly by the disorder or do they come about through experience with the symptoms of the disorder? In other words, do we know that the depression seen in patients with parkinson's is caused by the loss of dopaminergic neurons, or is it brought about through the frustration/helplessness the patient feels because of associated movement/cognitive problems?
    (18 votes)
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  • spunky sam blue style avatar for user Maistoryteller
    At , dopamine neurons are mentioned.
    Is it possible to inject dopamine neurons into the brain to help fight Parkinson's disease permanently?
    (9 votes)
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  • leaf blue style avatar for user Ethan Mehalchick
    Who discovered Parkinson's Disease
    (2 votes)
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    • starky sapling style avatar for user annabel
      Parkinson's disease was first mentioned in Nei Jing, the first Chinese medical text to appear, more than 2,500 years ago. In modern times, Parkinson's disease was first formally recognized in James Parkinson's "An Essay on the Shaking Palsy," which was published in 1817.
      (7 votes)
  • duskpin ultimate style avatar for user La Rouquine
    Are you more likely to have a genetic influence in the etiology of your Parkinson's the younger you are when you're diagnosed? For example, my grandmother was diagnosed before 50. Does having early-onset Parkinson's mean she's more likely to pass it on to me than if hers was the more common, late-onset type?
    (4 votes)
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  • blobby green style avatar for user tueyndahowz
    Does anyone know if there is a correlation between drug abuse and susceptibility to Parkinson's Disease? Are there connections between opiates and the disease? I wonder if this may be another unfortunate consequence of drug abuse.
    (2 votes)
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    • female robot grace style avatar for user Inger Hohler
      You may have heard that drug addicts are more susceptible to Parkinson's disease than the population at large. This is believed to be caused by impurities in street drugs. One such impurity is MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), which is a prodrug to a neurotoxin. MPTP is also a possible impurity in the production of opiates such as morphine and pethidine, which is why it's necessary with rigid rules for testing pharmaceuticals. Street drugs don't get tested for impurities. https://en.wikipedia.org/wiki/MPTP

      Another compound which cause the same reaction is the pesticide and insecticide rotenon. Farmers have long been known to be somewhat more susceptible to Parkinson's disease too, and it is believed that exposure to pesticides and insecticides could be the reason. Most likely there are more substances out there that can cause the same effects.

      The picture is somewhat complicated by the fact that a number of drugs, including street drugs, can produce symptoms that resemble Pakinson's disease, but aren't associated with real Parkinson's disease where Lewy bodies become part of the picture. This is often referred to as Parkinsonism, not Parkinson's disease. Without proper diagnostics it can be hard to tell them apart.

      Drug induced Parkinson's disease is also a side effect of certain over-the counter drugs. They are used on the basis that for certain illnesses it is better to treat the illness now and give the patient a better quality of life, and risk Parkinson's disease many years later, than not to relieve current symptoms.
      (4 votes)
  • leaf green style avatar for user Maria
    How come men get Parkinson's and women not that much?
    (3 votes)
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  • duskpin sapling style avatar for user Grace
    (Around ) What does it mean, that Parkinson's disease leads to Parkinsonism? And what are some examples of "other neurodegenerative diseases" that cause Parkinson's disease?
    (2 votes)
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    • piceratops ultimate style avatar for user ILoveToLearn
      The disease process causes the symptoms. It's a clumsy way to say that, but I think it's what was meant.

      Parkinsonism is a name for a small group of symptoms caused by damage to a specific part of the CNS.

      Parkinsonism can be secondary to drug use.

      "Drug-induced Parkinsonism

      Side effects of some drugs, especially those that affect dopamine levels in the brain such as anti-psychotic or anti-depressant medication, can actually cause symptoms of Parkinsonism.
      Although tremor and postural instability may be less severe, this condition may be difficult to distinguish from Parkinson’s disease.
      Medications that can cause the development of Parkinsonism include:
      Some calcium channel blockers
      Stimulants such as amphetamines and cocaine
      Usually after stopping those medications Parkinsonism gradually disappears over weeks to months
      Progressive Supranuclear Palsy (PSP)

      PSP is one of the more common forms of atypical Parkinsonism.
      Symptoms of PSP usually begin after age 50 and progress more rapidly than PD.
      These symptoms include: imbalance and frequent falls early on in the disease, rigidity of the trunk, voice and swallowing changes and eye-movement problems including the ability to move eyes up and down.
      Dementia develops later in the disease. There is no specific treatment for PSP.
      Dopaminergic medication treatment is often tried and may provide some modest benefit.
      Other therapies such as speech therapy, physical therapy, and antidepressants are important for management of patients with PSP.
      No laboratory/brain scan testing exists for PSP. In rare cases, some patients may have shrinking of a particular part of the brain, called the “Pons”, which can be seen on an MRI of the brain.

      Corticobasal Degeneration (CBD)

      CBD is the least common of the atypical causes of Parkinsonism
      CBD develops after age 60 and progresses more rapidly than PD.
      The initial symptoms of CBD include asymmetric bradykinesia, rigidity, limb dystonia and myoclonus (rapid jerking of a limb), postural instability, and disturbances of language.
      There is often marked and disabling apraxia of the affected limb, where it becomes difficult or impossible to perform coordinated movements of the affected limb even though there is no weakness or sensory loss. Sometimes this can be so severe that the movements of the affected limb cannot be controlled and is called ‘alien limb’ phenomenon.
      No laboratory/brain scan tests exist to confirm the diagnosis of CBD. CBD is a clinical diagnosis.
      There is no specific treatment for CBD.
      Supportive treatment such as botulinum toxin (Botox) for dystonia, antidepressants, speech and physical therapy may be helpful.
      Levodopa and dopamine agonists (common PD medications) seldom help.
      Multiple System Atrophy (MSA)

      MSA is a larger term for several disorders in which one or more system in the body deteriorates.
      Included in the category of MSA are: Shy-Drager syndrome (DSD), Striatonigral degeneration (SND) and OlivoPontoCerebellar Atrophy (OPCA).
      In 2007, a new classification was proposed with two major subtypes: MSA- P (similar to SND) in which parkinsonian signs predominate and MSA-C a cerebellar dysfunction type which resembles OPCA. The term Shy-Drager Syndrome is now rarely used.
      The mean age of onset is in the mid-50s.
      Symptoms include: bradykinesia, poor balance, abnormal autonomic function, rigidity, difficulty with coordination, or a combination of these features.
      Initially, it may be difficult to distinguish MSA from Parkinson’s disease, although more rapid progression, poor response to common PD medications, and development of other symptoms in addition to Parkinsonism, may be a clue to its diagnosis.
      No laboratory/brain scan testing exists to confirm the diagnosis of MSA.
      Patients respond poorly to PD medications, and may require higher doses than the typical PD patient for mild to modest benefits.
      Vascular Parkinsonism

      Multiple small strokes can cause Parkinsonism.
      Patients with this disorder are more likely to present with gait difficulty than tremor, and are more likely to have symptoms that are worse in the lower part of the body.
      Some will also report the abrupt onset of symptoms or give a history of step-wise deterioration (symptoms get worse, then plateau for a period).
      Dopamine is tried to improve patients’ mobility although the results are often not as successful.
      Vascular Parkinsonism is static (or very slowly progressive) when compared to other neurodegenerative disorders.
      Did you know that Dementia with Lewy Bodies is second to Alzheimer’s as the most common cause of dementia in the elderly?

      Dementia with Lewy bodies (DLB)

      DLB is a neurodegenerative disorder that results in progressive intellectual and functional deterioration.
      Patients with DLB usually have early dementia, prominent visual hallucinations, fluctuations in cognitive status over the day, and Parkinsonism.
      It is not uncommon for patients to present with cognitive problems particularly language problems, known as aphasia.
      Other cognitive changes in patients with DLB include deficits in attention, executive function (problem solving, planning) and visuospacial function (the ability to produce and recognize figures, drawing or matching figures).
      There are no known therapies to stop or slow the progression of DLB."

      (3 votes)
  • aqualine tree style avatar for user griffin.denomme
    how long will it take to have balance problams
    (3 votes)
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  • mr pants teal style avatar for user Sruti karthikeyan
    I have a small question, so my grandma had Parkinson's disease last year. What the doctor told was that she had mild Parkinson's effect on her, but was under treatment for a month. What does that mean?
    (1 vote)
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  • leaf green style avatar for user Vidhi
    So Parkinson's disease can never be cured permanently?
    (1 vote)
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Video transcript

- You may have heard of Parkinson's disease before. Maybe when you heard of someone raising money for the Michael J. Fox Foundation, or maybe you've listened to Muhammad Ali speaking about the disease. Both of these guys actually have Parkinson's disease, and they've done a really good job at raising money for, and awareness of, the disease. But what exactly is Parkinson's disease? Parkinson's disease is a progressive neurodegenerative disease. We call it a progressive disease because it progresses. It worsens over time. We say that it's a neurodegenerative disease because during the disease there's actually a loss, a degeneration, of neurons in the brain. In Parkinson's disease, we actually see a loss of a particular kind of neuron, and these neurons are called dopamine neurons. Dopamine neurons make a little signalling chemical called dopamine, which is really important for allowing us to make normal movements. A lot of these dopamine neurons live in an area of the brain called the substantia nigra. The substantia nigra we can see here. It sits here in the brain, above the spinal cord, in the part of the brain called the midbrain. When these neurons are lost, there's a reduction in the amount of dopamine in the brain. Again, that's because these neurons, they're used to make a lot of our dopamine and now they're not here anymore. And this is the really important part, because when there's this reduction in dopamine that's when we start to see the main movement signs of Parkinson's disease. Let's talk about these signs. One of these signs is shakiness, which can often be in the form of a tremor, maybe in the hand or the finger. A second sign is stiffness. That stiffness is felt when the person bends part of their body. Maybe the arm or the leg or the wrist. When they're bending that body part, let's say it's the arm, the movement just isn't very smooth. It doesn't feel very fluid anymore. Instead it actually feels really rigid. A third sign is slowed-down movements. This happens because it actually takes the person longer to complete a movement. A good way to think about this is to imagine the last time you were in water. Maybe you went to the pool, or you went to the beach to go swim in the ocean. You can probably remember trying to do a somersault underwater, or maybe running away from your friends. If you think back, you can remember that it actually took you a lot longer to do these things in water than it would have if you were on land. That's kind of what it's like for someone with these slowed-down movements. They can do them. It just takes a lot longer for them to do them. The fourth main sign is problems with balance. Feeling really unsteady, or really unstable when standing or walking around. Now, not all patients with Parkinson's disease will have all of these problems, but most will have them at some point during the course of the disease. Now, this last one that we talked about, the problems with balance, that usually crops up later on, once the person has had the disease for quite a few years. It's actually these first three that are normally used to decide whether or not someone has Parkinson's disease. All these main movement signs together actually form a symptom complex called Parkinsonism, or Parkinsonian syndrome. That means that Parkinson's is actually a disease that causes Parkinsonism. There are a few other neurodegenerative diseases that can cause Parkinsonism, this symptom complex that we're talking about. But Parkinson's disease is the most common, so because of this, we often call Parkinsonism caused by Parkinson's disease Primary Parkinsonism, and then we often called Parkinsonism caused by other neurodegenerative diseases Secondary Parkinsonism. Now, Parkinson's disease doesn't just cause Parkinsonism. Remember that this is a disease of the brain, and when things break down in our brain, our master control center, there's often more than one kind of symptom. People with Parkinson's disease can also experience psychiatric problems such as depression, cognitive problems such as memory loss and trouble with concentration, and lots of other non-movement symptoms. This can include problems with their sense of smell and problems with their sleeping patterns. The causes of Parkinson's disease are actually largely not known. For the majority of cases, we actually don't know what triggered the disease, so we call these cases ideopathic. "Ideopathic" meaning that the cause is unknown. While in the vast majority of cases there is no family history of the disease, about 15% of people actually do have a family history and for these people their Parkinson's appears to be caused by a mutation in one of a few different genes. Depending on which gene is the culprit, a mutation can either cause Parkinson's disease or it can increase a person's chance of getting Parkinson's disease. If someone has a problem with one of the genes that can actually cause the disease they'll definitely develop it, but if they have a problem with one of the genes that can increase the chance of getting Parkinson's disease, they may or may not develop the disease, but they are more likely to than someone who doesn't have the mutated gene. Genetics are the culprit once in a while, but again, most of the time, we don't know what caused Parkinson's disease. Despite this, there are some risk factors associated with developing the disease. A risk factor is something that increases your chances of developing a disease. You could say that having a certain gene mutation is a major risk factor for Parkinson's, but there are some other non-genetic risk factors as well. For example, exposure to certain pesticides and some cleaning chemicals. Older age, so once you get to about 60 years old your risk of developing Parkinson's disease increases and it continues to go up with each passing year. So as well we have a history of concussions as a risk factor of Parkinson's disease, and gender. For some reason, we're not entirely sure yet, men are a bit more likely than women to develop the disease. Another risk factor is regularly breathing in heavy metal particles like copper or manganese or lead. Maybe if you've lived in an industrial area where those might be found in the air. Again, these are risk factors for Parkinson's disease, which means that they're associated with a higher chance of developing the disease. The treatment of Parkinson's disease will normally involve medication to help deal with the movement symptoms, and to do that, the way that many of these medications work is by replacing or increasing dopamine levels in the brain because remember, our dopamine-producing neurons have degenerated during the disease, and for some patients, the medication works great. It may be all that they need to minimize the symptoms. But for most patients, after they've had the disease for several years, their medication just doesn't really cut it anymore, so when this happens, they may have surgery to help deal with their symptoms, and the goal of surgery is to inactivate areas in the brain that are causing their movement problems, like that shakiness or stiffness that we talked about earlier. This brings us to the long-term outlook for someone with Parkinson's disease. Unfortunately, Parkinson's disease is a progressive disease so the disease will continue to develop over the years after diagnosis is made. While none of our current methods are able to stop the disease, medication and surgery can be really helpful for managing the symptoms, and making sure the person with Parkinson's disease has a high quality of life for as long as possible. I just want to mention a common misconception that can crop up when we hear about Parkinson's disease, which is that Parkinson's disease only occurs in older people. While it is true that the average age of diagnosis is around 60 to 65, about five to 10 percent of patients are diagnosed before the age of 50. This is often referred to as young or early onset Parkinson's disease. For patients with young Parkinson's disease, those gene mutations we talked about earlier seem to be the cause more often than they are for patients diagnosed in the average 60 to 65 year-old range.