More than 50 experts on the use of deep brainstimulation for treatment of tremors and other symptoms of Parkinson’s disease have reached general agreement on when the surgical procedure should be considered and which patients might reap most benefits, a new report says.
The report, published in the online edition of Archives of Neurology, says the best candidates for deep brain stimulation are those who can’t tolerate the side effects ofmedication and those who don’t suffer from significant active cognitive or psychiatric problems but who do suffer from tremors or motor skills control.
In a deep brain stimulation procedure, a neurosurgeon surgically implants a neurostimulator in the brain in the location where abnormal electrical nerve signals generate the tremors and other symptoms common in Parkinson’s patients. The neurostimulator generates electric stimulation to the area to block the signals.
The report also says that:
Deep brain stimulation surgery is best performed by an experienced team and neurosurgeon who have expertise in stereotactic neurosurgery — microsurgery deep within the brain that is based on a three-dimensional coordinate system using advanced neuroimaging.
Deep brain stimulation is effective when used in the two most commonly treated areas of the brain, called the subthalamic nuclei and the globus pallidus pars interna. But treatment in the subthalamic nuclei may cause increased depressionand other symptoms in some patients.
Surgical removal of the area of the brain that causes Parkinson’s disease is an effective alternative and should be considered as an alternative in some people.
Surgical complication rates vary, with infection being the mostly commonly reported side effect of deep brain stimulation.
Making an Informed Decision
“We know that very little accessible information is out there to help a Parkinson’s patient make an informed decision as to whether he or she would be a good candidate for deep brain stimulation,” says report lead author Jeff Bronstein, MD, PhD, a professor of neurology at University of California, Los Angeles, in a news release.
Surgical studies take a long time, and what’s known about deep brain stimulation is focused, limited, and often written by one group, reflecting their opinions and biases, he says.
Bronstein says the results of a meeting in April 2009 of the Parkinson’s experts are intended to clarify some issues about the use of deep brain stimulation.
The FDA approved deep brain stimulation as a treatment for Parkinson’s disease in 2002, and since then more than 70,000 people have undergone the procedure. The authors write than more than 30% of failures of deep brain stimulation have been due to “inappropriate indications for surgery.”
The report says long-term improvements have been shown for up to five years for a number of Parkinson’s disease symptoms.
The experts caution that Parkinson’s disease continues to progress after deep brain stimulation.
Showing posts with label movement. Show all posts
Showing posts with label movement. Show all posts
Tuesday, October 19, 2010
Thursday, August 12, 2010
Parkinson's Disease Placebo Response Increases with Expectations
Individuals with Parkinson's disease were more likely to have a neurochemical response to a placebo medication if they were told they had higher odds of receiving an active drug.
Chicago, IL - infoZine - "The promise of symptom improvement that is elicited by a placebo is a powerful modulator of brain neurochemistry," the authors write as background information to a report in the August issue of Archives of General Psychiatry, one of the JAMA/Archives journals. "Understanding the factors that modify the strength of the placebo effect is of major clinical as well as fundamental scientific significance." In patients with Parkinson's disease, the expectation of symptom improvement is associated with the release of the neurotransmitter dopamine, and the manipulation of this expectation has been shown to affect the motor performance of patients with the condition.
Sarah C. Lidstone, Ph.D., of Pacific Parkinson's Research Centre at Vancouver Coastal Health and the University of British Columbia, Vancouver, Canada, and colleagues studied 35 patients with mild to moderate Parkinson's disease undergoing treatment with the medication levodopa. On the first day of the study, a baseline positron emission tomographic (PET) scan was performed, participants were given levodopa and a second scan was performed one hour later to assess dopamine response. On the second day, patients were randomly assigned to one of four groups, during which they were told they had either a 25-percent, 50-percent, 75-percent or 100-percent chance of receiving active medication before the third scan; however, all patients were given placebo.
Patients who were told they had a 75-percent chance of receiving active medication demonstrated a significant release of dopamine in response to the placebo, whereas those in the other groups did not.
Patients' reactions to the active medication before the first scan was also correlated with their response to placebo. "Importantly, whereas prior medication experience (i.e., the dopaminergic response to levodopa) was the major determinant of dopamine release in the dorsal striatum, expectation of clinical improvement (i.e., the probability determined by group allocation) was additionally required to drive dopamine release in the ventral striatum," the authors write. Both areas have been shown to be involved with reward processing; in patients with a chronic debilitating illness who have responded to therapy in the past, expectation of therapeutic benefit in response to placebo has been likened to the expectation of receiving a reward.
"Our findings may have important implications for the design of clinical trials, as we have shown that both the probability of receiving active treatment—which varies in clinical trials depending on the study design and the information provided to the patient—as well as the treatment history of the patient influence dopamine system activity and consequently clinical outcome," the authors conclude. "While our finding of a biochemical placebo response restricted to a 75 percent likelihood of receiving active treatment may not generalize to diseases other than Parkinson's disease, it is extremely likely that both probability and prior experience have similarly profound effects in those conditions."
This study was funded by the Michael Smith Foundation for Health Research, the Canadian Institutes for Health Research and a TRIUMF Life Sciences Grant. Dr. Stoessl is supported by the Canada Research Chairs Program.
Chicago, IL - infoZine - "The promise of symptom improvement that is elicited by a placebo is a powerful modulator of brain neurochemistry," the authors write as background information to a report in the August issue of Archives of General Psychiatry, one of the JAMA/Archives journals. "Understanding the factors that modify the strength of the placebo effect is of major clinical as well as fundamental scientific significance." In patients with Parkinson's disease, the expectation of symptom improvement is associated with the release of the neurotransmitter dopamine, and the manipulation of this expectation has been shown to affect the motor performance of patients with the condition.
Sarah C. Lidstone, Ph.D., of Pacific Parkinson's Research Centre at Vancouver Coastal Health and the University of British Columbia, Vancouver, Canada, and colleagues studied 35 patients with mild to moderate Parkinson's disease undergoing treatment with the medication levodopa. On the first day of the study, a baseline positron emission tomographic (PET) scan was performed, participants were given levodopa and a second scan was performed one hour later to assess dopamine response. On the second day, patients were randomly assigned to one of four groups, during which they were told they had either a 25-percent, 50-percent, 75-percent or 100-percent chance of receiving active medication before the third scan; however, all patients were given placebo.
Patients who were told they had a 75-percent chance of receiving active medication demonstrated a significant release of dopamine in response to the placebo, whereas those in the other groups did not.
Patients' reactions to the active medication before the first scan was also correlated with their response to placebo. "Importantly, whereas prior medication experience (i.e., the dopaminergic response to levodopa) was the major determinant of dopamine release in the dorsal striatum, expectation of clinical improvement (i.e., the probability determined by group allocation) was additionally required to drive dopamine release in the ventral striatum," the authors write. Both areas have been shown to be involved with reward processing; in patients with a chronic debilitating illness who have responded to therapy in the past, expectation of therapeutic benefit in response to placebo has been likened to the expectation of receiving a reward.
"Our findings may have important implications for the design of clinical trials, as we have shown that both the probability of receiving active treatment—which varies in clinical trials depending on the study design and the information provided to the patient—as well as the treatment history of the patient influence dopamine system activity and consequently clinical outcome," the authors conclude. "While our finding of a biochemical placebo response restricted to a 75 percent likelihood of receiving active treatment may not generalize to diseases other than Parkinson's disease, it is extremely likely that both probability and prior experience have similarly profound effects in those conditions."
This study was funded by the Michael Smith Foundation for Health Research, the Canadian Institutes for Health Research and a TRIUMF Life Sciences Grant. Dr. Stoessl is supported by the Canada Research Chairs Program.
Saturday, July 17, 2010
Treatments and drugs
By Mayo Clinic staff
There's no cure for Parkinson's disease, but medications can help control some of the symptoms of Parkinson's disease, and in some case, surgery may be helpful. Your doctor may recommend lifestyle changes, such as physical therapy, a healthy diet and exercise, in addition to medications.
Medications
Medications can help manage problems with walking, movement and tremor by increasing the brain's supply of dopamine. However, taking dopamine itself is not helpful, because it's unable to enter your brain.
Your initial response to Parkinson's treatment can be dramatic. Over time, however, the benefits of drugs frequently diminish or become less consistent, although symptoms can usually still be fairly well controlled.
Examples of medication your doctor may prescribe include:
Levodopa. The most effective Parkinson's drug is levodopa, which is a natural substance in the body. When taken by mouth in pill form, it passes into the brain and is converted to dopamine. Levodopa is combined with carbidopa to create the combination drug, Sinemet. The carbidopa protects levodopa from premature conversion to dopamine outside the brain; in doing that, it also prevents nausea. In Europe, levodopa is combined with a similar substance, benserazide, and is marketed as Madopar.
As the disease progresses, the benefit from levodopa may become less stable, with a tendency to wax and wane ("wearing off"). This then requires medication adjustments. Levodopa side effects include involuntary movements called dyskinesia. These resolve with dose reduction, but sometimes at the expense of reduced parkinsonism control. Like other Parkinson's drugs, it may also lower your blood pressure when standing.
Dopamine agonists. Unlike levodopa, these drugs aren't changed into dopamine. Instead, they mimic the effects of dopamine in the brain and cause neurons to react as though dopamine is present. They are not nearly as effective in treating the symptoms of Parkinson's disease. However, they last longer and are often used to smooth the sometimes off-and-on effect of levodopa.
This class includes pill forms of dopamine agonists, such as pramipexole (Mirapex) and ropinirole (Requip). A short-acting injectable dopamine agonist, apomorphine (Apokyn), is used for quick relief.
The side effects of dopamine agonists include hallucinations, sleepiness, water retention and low blood pressure when standing. These medications may also increase your risk of compulsive behaviors such as hypersexuality, compulsive gambling and compulsive overeating. If you are taking these medications and start behaving in a way that's out of character for you, talk to your doctor.
* MAO B inhibitors. These types of drugs, including selegiline (Eldepryl) and rasagiline (Azilect), help prevent the breakdown of both naturally occurring dopamine and dopamine formed from levodopa. They do this by inhibiting the activity of the enzyme monoamine oxidase B (MAO B) — an enzyme that metabolizes dopamine in the brain. Side effects are rare but may include confusion, headache, hallucinations and dizziness. These medications can't be used in combination with other antidepressants, the antibiotic ciprofloxacin (Cipro), the herb St. John's wort or certain narcotics. Check with your doctor before taking any additional medications with an MAO inhibitor.
* Catechol O-methyltransferase (COMT) inhibitors. These drugs prolong the effect of carbidopa-levodopa therapy by blocking an enzyme that breaks down levodopa. Tolcapone (Tasmar) has been linked to liver damage and liver failure, so it's normally used only in people who aren't responding to other therapies. Entacapone (Comtan) doesn't cause liver problems and is now combined with carbidopa and levodopa in a medication called Stalevo. However, it may worsen other levodopa side effects, such as involuntary movements (dyskinesias), nausea, confusion or hallucinations. It may cause urine discoloration.
* Anticholinergics. These drugs have been used for many years to help control the tremor associated with Parkinson's disease. A number of anticholinergic drugs, such as benztropine (Cogentin) and trihexyphenidyl, are available. However, their modest benefits are often offset by side effects such as impaired memory, confusion, constipation, dry mouth and eyes, and impaired urination.
* Glutamate (NMDA) blocking drugs. Doctors may prescribe amantadine (Symmetrel) alone to provide short-term relief of mild, early-stage Parkinson's disease. It also may be added to carbidopa-levodopa therapy for people in the later stages of Parkinson's disease, especially if they have problems with involuntary movements (dyskinesia) induced by carbidopa-levodopa. Side effects include a purple mottling of the skin and, sometimes, hallucinations.
Physical therapy
Exercise is important for general health, but especially for maintaining function in Parkinson's disease. Physical therapy may be advisable and can help improve your mobility, range of motion and muscle tone. Although specific exercises can't stop the progress of the disease, maintaining muscle strength and agility can help counter some of the progressive tendencies of the disease and also allow you to feel more confident and capable. A physical therapist can also work with you to improve your gait and balance. A speech therapist or speech pathologist can improve problems with speaking and swallowing.
Surgery
Deep brain stimulation is a surgical procedure used to treat Parkinson's disease. It involves implanting an electrode deep within the parts of your brain that control movement. The amount of stimulation delivered by the electrode is controlled by a pacemaker-like device placed under the skin in your upper chest. A wire that travels under your skin connects the device, called a pulse generator, to the electrodes.
Deep brain stimulation is most often used for people with advanced Parkinson's disease who have unstable medication (levodopa) responses. It can stabilize medication fluctuations and reduce or eliminate involuntary movements (dyskinesia). Tremor is especially responsive to this therapy.
Serious risks of this procedure are uncommon, but include brain hemorrhage or stroke. Infection is also a risk, and sometimes requires parts of the device to be replaced. Deep brain stimulation isn't beneficial for people who don't respond to carbidopa-levodopa.
There's no cure for Parkinson's disease, but medications can help control some of the symptoms of Parkinson's disease, and in some case, surgery may be helpful. Your doctor may recommend lifestyle changes, such as physical therapy, a healthy diet and exercise, in addition to medications.
Medications
Medications can help manage problems with walking, movement and tremor by increasing the brain's supply of dopamine. However, taking dopamine itself is not helpful, because it's unable to enter your brain.
Your initial response to Parkinson's treatment can be dramatic. Over time, however, the benefits of drugs frequently diminish or become less consistent, although symptoms can usually still be fairly well controlled.
Examples of medication your doctor may prescribe include:
Levodopa. The most effective Parkinson's drug is levodopa, which is a natural substance in the body. When taken by mouth in pill form, it passes into the brain and is converted to dopamine. Levodopa is combined with carbidopa to create the combination drug, Sinemet. The carbidopa protects levodopa from premature conversion to dopamine outside the brain; in doing that, it also prevents nausea. In Europe, levodopa is combined with a similar substance, benserazide, and is marketed as Madopar.
As the disease progresses, the benefit from levodopa may become less stable, with a tendency to wax and wane ("wearing off"). This then requires medication adjustments. Levodopa side effects include involuntary movements called dyskinesia. These resolve with dose reduction, but sometimes at the expense of reduced parkinsonism control. Like other Parkinson's drugs, it may also lower your blood pressure when standing.
Dopamine agonists. Unlike levodopa, these drugs aren't changed into dopamine. Instead, they mimic the effects of dopamine in the brain and cause neurons to react as though dopamine is present. They are not nearly as effective in treating the symptoms of Parkinson's disease. However, they last longer and are often used to smooth the sometimes off-and-on effect of levodopa.
This class includes pill forms of dopamine agonists, such as pramipexole (Mirapex) and ropinirole (Requip). A short-acting injectable dopamine agonist, apomorphine (Apokyn), is used for quick relief.
The side effects of dopamine agonists include hallucinations, sleepiness, water retention and low blood pressure when standing. These medications may also increase your risk of compulsive behaviors such as hypersexuality, compulsive gambling and compulsive overeating. If you are taking these medications and start behaving in a way that's out of character for you, talk to your doctor.
* MAO B inhibitors. These types of drugs, including selegiline (Eldepryl) and rasagiline (Azilect), help prevent the breakdown of both naturally occurring dopamine and dopamine formed from levodopa. They do this by inhibiting the activity of the enzyme monoamine oxidase B (MAO B) — an enzyme that metabolizes dopamine in the brain. Side effects are rare but may include confusion, headache, hallucinations and dizziness. These medications can't be used in combination with other antidepressants, the antibiotic ciprofloxacin (Cipro), the herb St. John's wort or certain narcotics. Check with your doctor before taking any additional medications with an MAO inhibitor.
* Catechol O-methyltransferase (COMT) inhibitors. These drugs prolong the effect of carbidopa-levodopa therapy by blocking an enzyme that breaks down levodopa. Tolcapone (Tasmar) has been linked to liver damage and liver failure, so it's normally used only in people who aren't responding to other therapies. Entacapone (Comtan) doesn't cause liver problems and is now combined with carbidopa and levodopa in a medication called Stalevo. However, it may worsen other levodopa side effects, such as involuntary movements (dyskinesias), nausea, confusion or hallucinations. It may cause urine discoloration.
* Anticholinergics. These drugs have been used for many years to help control the tremor associated with Parkinson's disease. A number of anticholinergic drugs, such as benztropine (Cogentin) and trihexyphenidyl, are available. However, their modest benefits are often offset by side effects such as impaired memory, confusion, constipation, dry mouth and eyes, and impaired urination.
* Glutamate (NMDA) blocking drugs. Doctors may prescribe amantadine (Symmetrel) alone to provide short-term relief of mild, early-stage Parkinson's disease. It also may be added to carbidopa-levodopa therapy for people in the later stages of Parkinson's disease, especially if they have problems with involuntary movements (dyskinesia) induced by carbidopa-levodopa. Side effects include a purple mottling of the skin and, sometimes, hallucinations.
Physical therapy
Exercise is important for general health, but especially for maintaining function in Parkinson's disease. Physical therapy may be advisable and can help improve your mobility, range of motion and muscle tone. Although specific exercises can't stop the progress of the disease, maintaining muscle strength and agility can help counter some of the progressive tendencies of the disease and also allow you to feel more confident and capable. A physical therapist can also work with you to improve your gait and balance. A speech therapist or speech pathologist can improve problems with speaking and swallowing.
Surgery
Deep brain stimulation is a surgical procedure used to treat Parkinson's disease. It involves implanting an electrode deep within the parts of your brain that control movement. The amount of stimulation delivered by the electrode is controlled by a pacemaker-like device placed under the skin in your upper chest. A wire that travels under your skin connects the device, called a pulse generator, to the electrodes.
Deep brain stimulation is most often used for people with advanced Parkinson's disease who have unstable medication (levodopa) responses. It can stabilize medication fluctuations and reduce or eliminate involuntary movements (dyskinesia). Tremor is especially responsive to this therapy.
Serious risks of this procedure are uncommon, but include brain hemorrhage or stroke. Infection is also a risk, and sometimes requires parts of the device to be replaced. Deep brain stimulation isn't beneficial for people who don't respond to carbidopa-levodopa.
Saturday, June 13, 2009
Treatments and drugs
Your initial response to Parkinson's treatment can be dramatic. Over time, however, the benefits of drugs frequently diminish or become less consistent, although symptoms can usually still be fairly well controlled. Your doctor may recommend lifestyle changes, such as physical therapy, a healthy diet and exercise, in addition to medications. In some cases, surgery may be helpful.
Medications
Medications can help manage problems with walking, movement and tremor by increasing the brain's supply of dopamine. Taking dopamine itself is not helpful, because it is unable to enter your brain.
*
Levodopa. The most effective Parkinson's drug is levodopa, which is a natural substance that we all have in our body. When taken by mouth in pill form, it passes into the brain and is converted to dopamine. Levodopa is combined with carbidopa to create the combination drug Sinemet. The carbidopa protects levodopa from premature conversion to dopamine outside the brain; in doing that, it also prevents nausea. In Europe, levodopa is combined with a similar substance, benserazide, and is marketed as Madopar.
As the disease progresses, the benefit from levodopa may become less stable, with a tendency to wax and wane ("wearing off"). This then requires medication adjustments. Levodopa side effects include confusion, delusions and hallucinations, as well as involuntary movements called dyskinesia. These resolve with dose reduction, but sometimes at the expense of reduced parkinsonism control.
*
Dopamine agonists. Unlike levodopa, these drugs aren't changed into dopamine. Instead, they mimic the effects of dopamine in the brain and cause neurons to react as though dopamine is present. They are not nearly as effective in treating the symptoms of Parkinson's disease. However, they last longer and are often used to smooth the sometimes off-and-on effect of levodopa.
This class includes pill forms of dopamine agonists, pramipexole (Mirapex) and ropinirole (Requip), as well as a patch form, rotigotine (Neupro). Pergolide (Permax) has been withdrawn from the market because of its association with heart valve problems. A short-acting injectable dopamine agonist, apomorphine (Apokyn), is used for quick relief.
The side effects of dopamine agonists include those of carbidopa-levodopa, although they're less likely to cause involuntary movements. However, they are substantially more likely to cause hallucinations, sleepiness or swelling. These medications may also increase your risk of compulsive behaviors such as hypersexuality, compulsive gambling and compulsive overeating. If you are taking these medications and start behaving in a way that's out of character for you, talk to your doctor.
* MAO B inhibitors. These types of drugs, including selegiline (Eldepryl) and rasagiline (Azilect), help prevent the breakdown of both naturally occurring dopamine and dopamine formed from levodopa. They do this by inhibiting the activity of the enzyme monoamine oxidase B (MAO B) — the enzyme that metabolizes dopamine in the brain. Side effects are rare but can include serious interactions with other medications, including drugs to treat depression and certain narcotics.
* Catechol O-methyltransferase (COMT) inhibitors. These drugs prolong the effect of carbidopa-levodopa therapy by blocking an enzyme that breaks down levodopa. Tolcapone (Tasmar) has been linked to liver damage and liver failure, so it's normally used only in people who aren't responding to other therapies. Entacapone (Comtan) doesn't cause liver problems and is now combined with carbidopa and levodopa in a medication called Stalevo.
* Anticholinergics. These drugs have been used for many years to help control the tremor associated with Parkinson's disease. A number of anticholinergic drugs, such as trihexyphenidyl and benztropine (Cogentin), are available. However, their modest benefits may be offset by side effects such as confusion and hallucinations, particularly in people over the age of 70. Other side effects include dry mouth, nausea, urine retention — especially in men with an enlarged prostate — and severe constipation.
* Antivirals. Doctors may prescribe amantadine (Symmetrel) alone to provide short-term relief of mild, early-stage Parkinson's disease. It also may be added to carbidopa-levodopa therapy for people in the later stages of Parkinson's disease, especially if they have problems with involuntary movements (dyskinesia) induced by carbidopa-levodopa. Side effects include swollen ankles and a purple mottling of the skin.
Physical therapy
Exercise is important for general health, but especially for maintaining function in Parkinson's disease. Physical therapy may be advisable and can help improve mobility, range of motion and muscle tone. Although specific exercises can't stop the progress of the disease, improving muscle strength can help you feel more confident and capable. A physical therapist can also work with you to improve your gait and balance. A speech therapist or speech pathologist can improve problems with speaking and swallowing.
Surgery
Deep brain stimulation is the most common surgical procedure to treat Parkinson's disease. It involves implanting an electrode deep within the parts of your brain that control movement. The amount of stimulation delivered by the electrode is controlled by a pacemaker-like device placed under the skin in your upper chest. A wire that travels under your skin connects the device, called a pulse generator, to the electrode.
Deep brain stimulation is most often used for people who have advanced Parkinson's disease who have unstable medication (levodopa) responses. It can stabilize medication fluctuations and reduce or eliminate involuntary movements (dyskinesias). Tremor is especially responsive to this therapy. Deep brain stimulation doesn't help dementia and may make that worse.
Like any other brain surgery, this procedure has risks — such as brain hemorrhage or stroke-like problems. Infection also may occur, requiring parts of the device to be replaced. In addition, the unit's battery beneath the skin of the chest wall must be surgically replaced every few years. Deep brain stimulation isn't beneficial for people who don't respond to carbidopa-levodopa.
Medications
Medications can help manage problems with walking, movement and tremor by increasing the brain's supply of dopamine. Taking dopamine itself is not helpful, because it is unable to enter your brain.
*
Levodopa. The most effective Parkinson's drug is levodopa, which is a natural substance that we all have in our body. When taken by mouth in pill form, it passes into the brain and is converted to dopamine. Levodopa is combined with carbidopa to create the combination drug Sinemet. The carbidopa protects levodopa from premature conversion to dopamine outside the brain; in doing that, it also prevents nausea. In Europe, levodopa is combined with a similar substance, benserazide, and is marketed as Madopar.
As the disease progresses, the benefit from levodopa may become less stable, with a tendency to wax and wane ("wearing off"). This then requires medication adjustments. Levodopa side effects include confusion, delusions and hallucinations, as well as involuntary movements called dyskinesia. These resolve with dose reduction, but sometimes at the expense of reduced parkinsonism control.
*
Dopamine agonists. Unlike levodopa, these drugs aren't changed into dopamine. Instead, they mimic the effects of dopamine in the brain and cause neurons to react as though dopamine is present. They are not nearly as effective in treating the symptoms of Parkinson's disease. However, they last longer and are often used to smooth the sometimes off-and-on effect of levodopa.
This class includes pill forms of dopamine agonists, pramipexole (Mirapex) and ropinirole (Requip), as well as a patch form, rotigotine (Neupro). Pergolide (Permax) has been withdrawn from the market because of its association with heart valve problems. A short-acting injectable dopamine agonist, apomorphine (Apokyn), is used for quick relief.
The side effects of dopamine agonists include those of carbidopa-levodopa, although they're less likely to cause involuntary movements. However, they are substantially more likely to cause hallucinations, sleepiness or swelling. These medications may also increase your risk of compulsive behaviors such as hypersexuality, compulsive gambling and compulsive overeating. If you are taking these medications and start behaving in a way that's out of character for you, talk to your doctor.
* MAO B inhibitors. These types of drugs, including selegiline (Eldepryl) and rasagiline (Azilect), help prevent the breakdown of both naturally occurring dopamine and dopamine formed from levodopa. They do this by inhibiting the activity of the enzyme monoamine oxidase B (MAO B) — the enzyme that metabolizes dopamine in the brain. Side effects are rare but can include serious interactions with other medications, including drugs to treat depression and certain narcotics.
* Catechol O-methyltransferase (COMT) inhibitors. These drugs prolong the effect of carbidopa-levodopa therapy by blocking an enzyme that breaks down levodopa. Tolcapone (Tasmar) has been linked to liver damage and liver failure, so it's normally used only in people who aren't responding to other therapies. Entacapone (Comtan) doesn't cause liver problems and is now combined with carbidopa and levodopa in a medication called Stalevo.
* Anticholinergics. These drugs have been used for many years to help control the tremor associated with Parkinson's disease. A number of anticholinergic drugs, such as trihexyphenidyl and benztropine (Cogentin), are available. However, their modest benefits may be offset by side effects such as confusion and hallucinations, particularly in people over the age of 70. Other side effects include dry mouth, nausea, urine retention — especially in men with an enlarged prostate — and severe constipation.
* Antivirals. Doctors may prescribe amantadine (Symmetrel) alone to provide short-term relief of mild, early-stage Parkinson's disease. It also may be added to carbidopa-levodopa therapy for people in the later stages of Parkinson's disease, especially if they have problems with involuntary movements (dyskinesia) induced by carbidopa-levodopa. Side effects include swollen ankles and a purple mottling of the skin.
Physical therapy
Exercise is important for general health, but especially for maintaining function in Parkinson's disease. Physical therapy may be advisable and can help improve mobility, range of motion and muscle tone. Although specific exercises can't stop the progress of the disease, improving muscle strength can help you feel more confident and capable. A physical therapist can also work with you to improve your gait and balance. A speech therapist or speech pathologist can improve problems with speaking and swallowing.
Surgery
Deep brain stimulation is the most common surgical procedure to treat Parkinson's disease. It involves implanting an electrode deep within the parts of your brain that control movement. The amount of stimulation delivered by the electrode is controlled by a pacemaker-like device placed under the skin in your upper chest. A wire that travels under your skin connects the device, called a pulse generator, to the electrode.
Deep brain stimulation is most often used for people who have advanced Parkinson's disease who have unstable medication (levodopa) responses. It can stabilize medication fluctuations and reduce or eliminate involuntary movements (dyskinesias). Tremor is especially responsive to this therapy. Deep brain stimulation doesn't help dementia and may make that worse.
Like any other brain surgery, this procedure has risks — such as brain hemorrhage or stroke-like problems. Infection also may occur, requiring parts of the device to be replaced. In addition, the unit's battery beneath the skin of the chest wall must be surgically replaced every few years. Deep brain stimulation isn't beneficial for people who don't respond to carbidopa-levodopa.
Saturday, May 2, 2009
Parkinson's Disease: More Than Shaking Going On Researchers discovering non-motor symptoms may happen first
Parkinson's Disease: More Than Shaking Going On Researchers discovering non-motor symptoms may happen first
(live-PR.com) - TORONTO, ONTARIO -- (Marketwire) -- 04/21/09 -- Parkinson's is much more than a tremor. That's a message Parkinson Society Canada hopes to drive home this April during Parkinson's Awareness Month.
In Parkinson's, the most common symptoms are movement-related: tremor, slowness, muscle stiffness and balance problems. However, by the time Parkinson's is diagnosed, people have already lost 60 to 70 percent of the dopamine-producing cells. Now researchers are discovering that non-motor symptoms such as sleep problems, depression and smell loss may represent the earliest signs of Parkinson's, for some people, and may appear years before the diagnosis.
In research at Montreal's Sacre-Coeur Hospital, Dr. Ronald Postuma, assistant professor of neurology at McGill University found that people with a rare sleep disorder where they physically acted out their dreams had a 50% risk of developing Parkinson's disease or dementia within 12 years. The patients had REM-sleep behaviour disorder, which Postuma describes as "punching and yelling or kicking out while asleep. It mostly affects people in their 60s and 70s, almost always men." Not all will develop a neurodegenerative disease but Postuma says, "Patients with true REM-sleep behaviour disorder have a considerable risk of developing Parkinson's disease."
Depression and anxiety can surface early in Parkinson's. "Many people, as they're starting to lose their dopamine, may not yet have developed a tremor, slowness or trouble walking, but may feel anxious and depressed," says Dr. Susan Fox, assistant professor of neurology at University of Toronto. "Depression is also part of Parkinson's disease itself and not just a reaction to having a chronic neurological disorder." Fox notes untreated depression can reduce quality of life.
Smell loss is a common occurrence. "The general consensus is that the changes in olfaction (sense of smell) occur about five years before the Parkinson's diagnosis." says Dr. Harold Robertson, a professor in the Brain Repair Centre and Department of Pharmacology at Dalhousie University in Halifax. "That could give us enough lead time to try to stop the process."
Joyce Gordon, Parkinson Society Canada President and CEO says "The more dollars we can put towards Parkinson's research, the sooner we may be able to establish if there is a definite link to Parkinson's when a person has sleep problems, depression or loss of smell. This would lay the groundwork for developing treatments to delay or stop this debilitating disease in its tracks. The answers can't come soon enough for the 100,000 Canadians who have Parkinson's disease and those who are unknowingly at risk."
In the meantime, the first step for anyone experiencing difficulties with sleep or mood is to see a doctor for a proper diagnosis. REM sleep behaviour disorder and depression are treatable. Smell loss is not currently treatable but is worth mentioning to the doctor, during a routine visit, as it may be due to a variety of causes.
Parkinson's is a progressive neurological disease for which there is no known cause or cure. When cells in the brain that normally produce a chemical called "dopamine" die, symptoms of Parkinson's appear. The most common symptoms are: tremor (shaking), slowness in movements, muscle stiffness and problems with balance. Other symptoms that may also occur for some people include fatigue, difficulties with speech and writing, sleep disorders, depression and cognitive changes.
For over 40 years, Parkinson Society Canada (PSC) has been the national voice of people living with Parkinson's disease. PSC has over 230 chapters and support groups. PSC's mission is to fund research, support services, advocacy and education.
For more information on Parkinson's disease and Parkinson Society Canada, visit the PSC website at www.parkinson.ca : www.parkinson.ca or call 1-800-565-3000.
Contacts:
Parkinson Society Canada
John Provenzano
416-227-3399 or 1-800-565-3000 ext 3399
John.provenzano@parkinson.ca : John.provenzano@parkinson.ca
(live-PR.com) - TORONTO, ONTARIO -- (Marketwire) -- 04/21/09 -- Parkinson's is much more than a tremor. That's a message Parkinson Society Canada hopes to drive home this April during Parkinson's Awareness Month.
In Parkinson's, the most common symptoms are movement-related: tremor, slowness, muscle stiffness and balance problems. However, by the time Parkinson's is diagnosed, people have already lost 60 to 70 percent of the dopamine-producing cells. Now researchers are discovering that non-motor symptoms such as sleep problems, depression and smell loss may represent the earliest signs of Parkinson's, for some people, and may appear years before the diagnosis.
In research at Montreal's Sacre-Coeur Hospital, Dr. Ronald Postuma, assistant professor of neurology at McGill University found that people with a rare sleep disorder where they physically acted out their dreams had a 50% risk of developing Parkinson's disease or dementia within 12 years. The patients had REM-sleep behaviour disorder, which Postuma describes as "punching and yelling or kicking out while asleep. It mostly affects people in their 60s and 70s, almost always men." Not all will develop a neurodegenerative disease but Postuma says, "Patients with true REM-sleep behaviour disorder have a considerable risk of developing Parkinson's disease."
Depression and anxiety can surface early in Parkinson's. "Many people, as they're starting to lose their dopamine, may not yet have developed a tremor, slowness or trouble walking, but may feel anxious and depressed," says Dr. Susan Fox, assistant professor of neurology at University of Toronto. "Depression is also part of Parkinson's disease itself and not just a reaction to having a chronic neurological disorder." Fox notes untreated depression can reduce quality of life.
Smell loss is a common occurrence. "The general consensus is that the changes in olfaction (sense of smell) occur about five years before the Parkinson's diagnosis." says Dr. Harold Robertson, a professor in the Brain Repair Centre and Department of Pharmacology at Dalhousie University in Halifax. "That could give us enough lead time to try to stop the process."
Joyce Gordon, Parkinson Society Canada President and CEO says "The more dollars we can put towards Parkinson's research, the sooner we may be able to establish if there is a definite link to Parkinson's when a person has sleep problems, depression or loss of smell. This would lay the groundwork for developing treatments to delay or stop this debilitating disease in its tracks. The answers can't come soon enough for the 100,000 Canadians who have Parkinson's disease and those who are unknowingly at risk."
In the meantime, the first step for anyone experiencing difficulties with sleep or mood is to see a doctor for a proper diagnosis. REM sleep behaviour disorder and depression are treatable. Smell loss is not currently treatable but is worth mentioning to the doctor, during a routine visit, as it may be due to a variety of causes.
Parkinson's is a progressive neurological disease for which there is no known cause or cure. When cells in the brain that normally produce a chemical called "dopamine" die, symptoms of Parkinson's appear. The most common symptoms are: tremor (shaking), slowness in movements, muscle stiffness and problems with balance. Other symptoms that may also occur for some people include fatigue, difficulties with speech and writing, sleep disorders, depression and cognitive changes.
For over 40 years, Parkinson Society Canada (PSC) has been the national voice of people living with Parkinson's disease. PSC has over 230 chapters and support groups. PSC's mission is to fund research, support services, advocacy and education.
For more information on Parkinson's disease and Parkinson Society Canada, visit the PSC website at www.parkinson.ca : www.parkinson.ca or call 1-800-565-3000.
Contacts:
Parkinson Society Canada
John Provenzano
416-227-3399 or 1-800-565-3000 ext 3399
John.provenzano@parkinson.ca : John.provenzano@parkinson.ca
Sunday, April 19, 2009
Shedding some light on Parkinson's treatment
Shedding some light on Parkinson's treatment
EUREKALERT
Contact: Lisa Van Pay
lvanpay@nsf.gov
703-292-8796
National Science Foundation
Scientists use optical approach to study deep brain stimulation
A research team lead by Karl Deisseroth in the bioengineering department at Stanford University has developed a technique to systematically characterize disease circuits in the brain. By precisely controlling individual components of the circuit implicated in Parkinson's disease, the team has identified a specific group of cells as direct targets of deep brain stimulation (DBS), a Parkinson's treatment.
Termed optogenetics, the NSF-funded technology uses light-activated proteins, originally isolated from bacteria, in combination with genetic approaches to control specific parts of the brain. The technique is a vast improvement over previous methods because it allows researchers to precisely stimulate neurons and measure the effect of treatment simultaneously in animals with Parkinson's-like symptoms.
Published in the April 17 issue of Science, Deisseroth's team found they could reduce disease symptoms by preferentially activating neurons that link to the subthalamic nucleus region of the brain. First, these specific cells were treated in a way that made them sensitive to stimulation by blue light, then the team implanted an optical fiber in the brain.
When researchers rapidly flashed blue light inside the animals' brains the disease symptoms improved. In contrast, treating with slower flashes of light actually made the symptoms worse, and targeting other kinds of cells had no effect at all, indicating both proper cell type and stimulation frequency are crucial components of effective treatment. Flashing blue light on portions of the same neurons found closer to the outer surface of the brain had an effect similar to treatment deep within the brain, raising the possibility that researchers may be able to develop treatments that are less invasive than current options.
Approved as a medical treatment in 1997, DBS remains controversial because it doesn't work on all patients. Used to treat Parkinson's disease, depression and movement disorders, DBS involves surgical implantation of a brain pacemaker, which sends electrical impulses into the brain. In the past, researchers have been unable to understand the effective mechanism of DBS because the electrical signal emitted by DBS devices interferes with the ability to observe brain activity.
Explains Deisseroth, "The brain is an electrical device, but it is a very complicated device. Think of it as an orchestra without sections: all of the types of instruments, or cells, are mixed together. Treatments like DBS are unrefined, in that they stimulate all of the cells or instruments. The optogenetic approach allows us to control stimulation of specific cells in the brain on the appropriate timescale, much like a conductor directing specific sections of an orchestra at the appropriate time."
Production of new therapies is always a long-term goal, but for now Deisseroth and his group are focused on mapping disease circuits and understanding brain function. "We need to understand the players before we can develop effective treatment strategies," he stated.
EUREKALERT
Contact: Lisa Van Pay
lvanpay@nsf.gov
703-292-8796
National Science Foundation
Scientists use optical approach to study deep brain stimulation
A research team lead by Karl Deisseroth in the bioengineering department at Stanford University has developed a technique to systematically characterize disease circuits in the brain. By precisely controlling individual components of the circuit implicated in Parkinson's disease, the team has identified a specific group of cells as direct targets of deep brain stimulation (DBS), a Parkinson's treatment.
Termed optogenetics, the NSF-funded technology uses light-activated proteins, originally isolated from bacteria, in combination with genetic approaches to control specific parts of the brain. The technique is a vast improvement over previous methods because it allows researchers to precisely stimulate neurons and measure the effect of treatment simultaneously in animals with Parkinson's-like symptoms.
Published in the April 17 issue of Science, Deisseroth's team found they could reduce disease symptoms by preferentially activating neurons that link to the subthalamic nucleus region of the brain. First, these specific cells were treated in a way that made them sensitive to stimulation by blue light, then the team implanted an optical fiber in the brain.
When researchers rapidly flashed blue light inside the animals' brains the disease symptoms improved. In contrast, treating with slower flashes of light actually made the symptoms worse, and targeting other kinds of cells had no effect at all, indicating both proper cell type and stimulation frequency are crucial components of effective treatment. Flashing blue light on portions of the same neurons found closer to the outer surface of the brain had an effect similar to treatment deep within the brain, raising the possibility that researchers may be able to develop treatments that are less invasive than current options.
Approved as a medical treatment in 1997, DBS remains controversial because it doesn't work on all patients. Used to treat Parkinson's disease, depression and movement disorders, DBS involves surgical implantation of a brain pacemaker, which sends electrical impulses into the brain. In the past, researchers have been unable to understand the effective mechanism of DBS because the electrical signal emitted by DBS devices interferes with the ability to observe brain activity.
Explains Deisseroth, "The brain is an electrical device, but it is a very complicated device. Think of it as an orchestra without sections: all of the types of instruments, or cells, are mixed together. Treatments like DBS are unrefined, in that they stimulate all of the cells or instruments. The optogenetic approach allows us to control stimulation of specific cells in the brain on the appropriate timescale, much like a conductor directing specific sections of an orchestra at the appropriate time."
Production of new therapies is always a long-term goal, but for now Deisseroth and his group are focused on mapping disease circuits and understanding brain function. "We need to understand the players before we can develop effective treatment strategies," he stated.
Monday, March 30, 2009
23andMe already testing for rare Parkinson's mutations?
23andMe already testing for rare Parkinson's mutations?
Posted on: March 23, 2009 9:15 AM, by Daniel MacArthur
This casual aside on a recent post on personal genomics company 23andMe's corporate blog caught my eye:
Mutations in several other genes have also been associated with Parkinson's disease, but these are extremely rare. Many have been found only in one or two families. While these mutations are so rare that they are not covered by 23andMe (to date we have found no customers with any of them), studying them could help scientists better understand the mechanisms of Parkinson's generally... [my emphasis]
In other words, the company already has probes on its custom chip targeting these variants, but it isn't yet reporting results back to customers.
Why isn't it reporting back? If you'd asked me a couple of months ago, I'd say the motivation was probably to avoid the regulatory hassles associated with testing overtly clinical markers - but the company's willingness to provide results for large-effect variants associated with breast cancer pretty much rules that out.
Instead, the most likely reason to hold back on giving results back to consumers is (perfectly reasonable) caution about the reliability of the test. Screening for extremely rare variants is tricky for two reasons: firstly, since there are very few individuals around who carry the mutation, obtaining positive controls is difficult; and secondly, screening accuracy needs to be extremely high to keep down the rate of false positives.
To illustrate that last point, let's say there was a genetic variant with a population frequency of just 0.1% (1 in every 1000 people carry it)*. Now, let's say you have a test with false positive and false negative rates of just 1 in every 1000 tests, and you run that test on one million people. Of the 1000 carriers in the population, the test will only miss one; but it will also give a positive result for 999 people who are non-carriers. In other words, even for this extremely accurate hypothetical test, only 50% of the people who test positive are actually carriers.
This means that testing for rare variants requires exceptionally high standards of accuracy, probably higher than could reasonably be expected from chip-based assays. Given the risks of reporting potentially unreliable results back to customers for serious risk variants it makes good sense for 23andMe to hold off until it has developed extra assays for quality control; and it's unlikely to do this until it has seen at least a few customers who actually do test positive for the variant in question.
As for obtaining samples from real carriers to enable the development of validation assays: what better way to do that than to recruit 10,000 customers suffering from Parkinson's? Targeted recruitment of customers with other diseases will no doubt follow.
It is now abundantly clear that 23andMe is intent on moving into the overtly clinical domain; Navigenics' purchase of its Affymetrix testing lab and deCODE's move into disease-specific genetic tests are other signs that this is a shift that will involve the entire personal genomics industry.
Personal genomics is getting serious.
Posted on: March 23, 2009 9:15 AM, by Daniel MacArthur
This casual aside on a recent post on personal genomics company 23andMe's corporate blog caught my eye:
Mutations in several other genes have also been associated with Parkinson's disease, but these are extremely rare. Many have been found only in one or two families. While these mutations are so rare that they are not covered by 23andMe (to date we have found no customers with any of them), studying them could help scientists better understand the mechanisms of Parkinson's generally... [my emphasis]
In other words, the company already has probes on its custom chip targeting these variants, but it isn't yet reporting results back to customers.
Why isn't it reporting back? If you'd asked me a couple of months ago, I'd say the motivation was probably to avoid the regulatory hassles associated with testing overtly clinical markers - but the company's willingness to provide results for large-effect variants associated with breast cancer pretty much rules that out.
Instead, the most likely reason to hold back on giving results back to consumers is (perfectly reasonable) caution about the reliability of the test. Screening for extremely rare variants is tricky for two reasons: firstly, since there are very few individuals around who carry the mutation, obtaining positive controls is difficult; and secondly, screening accuracy needs to be extremely high to keep down the rate of false positives.
To illustrate that last point, let's say there was a genetic variant with a population frequency of just 0.1% (1 in every 1000 people carry it)*. Now, let's say you have a test with false positive and false negative rates of just 1 in every 1000 tests, and you run that test on one million people. Of the 1000 carriers in the population, the test will only miss one; but it will also give a positive result for 999 people who are non-carriers. In other words, even for this extremely accurate hypothetical test, only 50% of the people who test positive are actually carriers.
This means that testing for rare variants requires exceptionally high standards of accuracy, probably higher than could reasonably be expected from chip-based assays. Given the risks of reporting potentially unreliable results back to customers for serious risk variants it makes good sense for 23andMe to hold off until it has developed extra assays for quality control; and it's unlikely to do this until it has seen at least a few customers who actually do test positive for the variant in question.
As for obtaining samples from real carriers to enable the development of validation assays: what better way to do that than to recruit 10,000 customers suffering from Parkinson's? Targeted recruitment of customers with other diseases will no doubt follow.
It is now abundantly clear that 23andMe is intent on moving into the overtly clinical domain; Navigenics' purchase of its Affymetrix testing lab and deCODE's move into disease-specific genetic tests are other signs that this is a shift that will involve the entire personal genomics industry.
Personal genomics is getting serious.
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