In 1817, a book called An Essay on the Shaking Palsy was published in which James Parkinson describes 6 patients who all demonstrated a similar collection of symptoms. He described the individuals as having increased tone in their muscles, slow and reduced movements, a stooped posture and a resting tremor. Decades later, famous french neurologist Jean-Martin Charcot coined the term “Parkinson’s Disease” and the description of the disease in medical textbooks remains much the same today (although additional symptoms involving altered cognitive abilities, problems with impulse control, sleep disturbance, vision abnormalities and others have also been included).
What do we know?
We know that in Parkinson’s Disease, cells that secrete the neurotransmitter dopamine in the depths of the brain die, affecting systems that control body movement, eye movements, emotional and cognitive functions. By the time someone starts to show motor symptoms, it is estimated that as many as 40-60% of these cells are already gone, and it is thought that the brain is able to compensate for their loss up until this point. Although scientists are still exploring the cause of this cell degeneration, one thing we do know is that when we look at these dopamine secreting cells from someone with Parkinson’s disease under a microscope, we can see what we call Lewy bodies. This is the brown blob seen inside the brain cell below. Lewy bodies can be thought of as junk and signal bad cell health.
What is not known?
Scientists are still working towards a complete understanding of Parkinson’s Disease. You may wonder how, if we have had a consistent description of the symptoms for hundreds of years, is there still so much that we don’t know. Take this example:
A few years ago, a 58 year old man, who had suffered from Parkinson’s for over 10 years, went to see Dr. Bastiaan Bloem in the Netherlands. This man’s brain had been ravaged by the disease and by the time Dr. Bloem saw him, he was barely able to walk on his own. When he tried to walk, often he froze in one place unable to even take a step or if he did, he could only take a few before falling over. But this man told Dr. Bloem something amazing, “Yesterday I rode my bicycle for 10 kilometers.” Dr. Bloem was in disbelief, and it was only after seeing it with his own eyes that he could start believing it.
Watch the video here: https://www.youtube.com/watch?v=aaY3gz5tJSk
It is still unknown why someone who is barely able to stand and walk on his own is able to smoothly ride a bicycle. Maybe the feedback the individual is getting from the pedals is allowing consistent movement initiation (something not present while walking) or perhaps riding is using a different part of the brain than walking. There have been reports of people with Parkinson’s Disease being able to dance, run, walk smoothly when given specific emotional or visual cues. It is still not clearly understood why this occurs, and more work is needed on how the motor system works to be able to explain these strange reports.
Are there treatments?
The most common treatment for Parkinson’s Disease is a drug that increases concentrations of dopamine in the nervous system called L-Dopa; however, more recently a surgery that implants an electrode into the depths of the brain has become more popular. This is called deep brain stimulation, and it has revolutionized treatment options for people diagnosed with Parkinson’s, especially those with early onset.
Check out this video that shows the amazing effects of deep brain stimulation for a patient with Parkinson’s Disease: https://www.youtube.com/watch?v=uBh2LxTW0s0
I have been absolutely fascinated by how well this surgery can work for some people and also the most important detail: neurosurgeons and neuroscientists still don’t really understand why placing an electrode in this one spot in the brain even has this effect!
This is just a very brief overview of some of the things I find most interesting about research on Parkinson’s Disease. There is a wealth of information out there, and some people spend their whole careers studying it. With the advancement of technology that allows us to sequence genes, stain cells, and image whole brains of living people suffering from this disease, we are inching closer to better treatments, and maybe even one day, a cure.