mjanes 's List: Parkinson's Disease

• Kanthasamy's research shows that there is specific protein that is naturally present in human brains that -- for no known reason -- kills the brain cells that make dopamine.

   

  The cells that are being killed are the ones that produce the needed dopamine.

   

  "We have millions of cells in our brains," said Kanthasamy, "In Parkinson's, about 10,000 of these brain cells die; no one knows why."

   

  Kanthasamy discovered that a novel protein -- known as protein kinase-C (specifically PKCδ) -- is killing the dopamine-producing cells.

• Stereotactic radiosurgery (SRS) offers a less invasive way to eliminate tremors caused by Parkinson's disease and essential tremor than deep brain stimulation (DBS) and radiofrequency (RF) treatments, and is as effective, according to a long-term study presented November 2, 2009,
• The study shows that radiosurgery is an effective and safe method of getting rid of tremors caused by Parkinson's disease and essential tremor, with outcomes that favorably compare to both DBS and RF in tremor relief and risk of complications at seven years after treatment,"
• In view of these long-term results, this non-invasive procedure should be considered a primary treatment option for tremors that are hard to treat."
• Stereotactic radiation is a specialized type of external beam radiation therapy that pinpoints high doses of radiation directly on a confined area in a shorter amount of time than traditional radiation treatments. Stereotactic radiosurgery, or SRS, refers to a single or several stereotactic radiation treatments of the brain or spine.
• With a median follow-up of seven years, 84 percent of patients had significant or complete resolution of tremors. In patients with Parkinson's disease, 83 percent had near or complete tremor resolution, while those with essential tremor had 87 percent of this degree of tremor resolution.

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• many of the problems suffered by patients with Parkinson´s disease - difficulties in initiating actions, slow laboured movements and tremors - can be understood in terms of damage to control circuits in the brain responsible for habits. 
  
   The analysis, which is published online and will appear in the November issue of Nature Reviews Neuroscience, has involved combining the experience of an international team of clinical experts to explain why, paradoxically, removal of part of the brain can help sufferers of Parkinson´s disease regain smooth initiation of movements. 
  
   An important processing unit in the brain (the basal ganglia) is part of two behavioural control circuits - habitual control, which directs our fast, stimulus-driven automatic, largely unconscious movements; and voluntary goal-directed control, which is driven by a conscious appreciation of the action´s outcome. This means goal-directed movements are typically slower, require effort, and can only be done one at a time. Different regions of the basal ganglia are involved in goal-directed and habitual control. An important proposal in the Nature Reviews Neuroscience article is that Parkinson´s disease is linked to a preferential loss of the neurotransmitter dopamine from the regions involved in habitual control. 
  
   Many of the symptoms of Parkinson´s disease can therefore be understood in terms of a catastrophic loss of habits, which means patients have to rely on the goal-directed control system for everything they do. This idea can explain why their movements are slow, effortful and easily interrupted. For example, when approaching a narrow door or object, a patient with Parkinson´s disease can suddenly freeze and find it difficult to start again. Under serial goal-directed control, (i.e. you can only think about doing one thing at a time), when the patient stops thinking about walking and starts to think about going through the door or avoiding the object, they stop walking. 
  
   The proposed analysis offers a further important insight into the symptoms of Parkinson´s disease. At the level of the basal ganglia, the goal-directed and habitual control circuits are physically separated, but down-stream, they converge on shared motor systems (that is, we can do the same action either under goal-directed or habitual control). Numerous experiments show that the loss of dopamine from the basal ganglia increases inhibitory output from the habitual control circuits. Therefore, for a patient with Parkinson´s disease to express goal-directed behaviour, they have to overcome the distorting inhibitory signals from the malfunctioning habitual control system. This provides a further reason for why patients find it so difficult to initiate and maintain actions and why their behaviour is so effortful and slow. 
  
   These ideas also offer a potential resolution of a continuing paradox in Parkinson´s disease research - why destruction of the parts of the basal ganglia responsible for habits can have such a beneficial effect on Parkinson´s disease. Professor Redgrave and his team propose that removal of the distorting inhibitory output from habitual control circuits could make it easier for goal-directed behaviour to be expressed. 
  
   It is hoped this new interpretation of Parkinson´s disease will help in the discovery of new cures and treatment in the future for the 120,000 people in the UK suffering with the disease.

• Parkinson's disease (PD) belongs to a group of conditions called motor system disorders, which are the result of the loss  of dopamine-producing brain cells. The four primary symptoms of PD are tremor, or trembling in hands, arms, legs, jaw, and  face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired  balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking, or completing  other simple tasks. PD usually affects people over the age of 50.  Early symptoms of PD are subtle and occur gradually.  In  some people the disease progresses more quickly than in others.  As the disease progresses, the shaking, or tremor, which  affects the majority of PD patients may begin to interfere with daily activities.  Other symptoms may include depression and  other emotional changes; difficulty in swallowing, chewing, and speaking; urinary problems or constipation; skin problems;  and sleep disruptions.  There are currently no blood or laboratory tests that have been proven to help in diagnosing sporadic  PD.  Therefore the diagnosis is based on medical history and a neurological examination.  The disease can be difficult to  diagnose accurately.   Doctors may sometimes request brain scans or laboratory tests in order to rule out other diseases.