Parkinson Disease is the second most common neurodegenerative disease in the U.S. and it appears to be increasing in prevalence. So what is Parkinson Disease, what causes it and what can we do about it? 2 Docs Talk about it today.
[00:00:00] Parkinson’s disease is the second most common neurodegenerative disease in the U.S..
[00:00:05] Right. There are about a million people in the U.S. diagnosed with Parkinson’s and incidence of Parkinson’s is expected to increase as our population ages.
[00:00:13] So let’s talk about Parkinson’s disease what it is and what doctors and patients need to know about it.
[00:00:18] Hello and welcome to 2 docs talk. The podcast about health care, the science of medicine, and everything in between.
[00:00:24] So first things first. These days we are not supposed to say Parkinson’s disease.
[00:00:29] Drop the S it’s not possessive Dr. Parkinson does not own the disease.
[00:00:33] That goes for pretty much all diseases right?
[00:00:35] Yeah. That’s out. But that sounds and feels so wrong. Parkinson disease.
[00:00:40] Well this is the latest trend in medical nomenclature. for all the diseases that are named after the person who originally described them, we are now supposed to drop the S.
[00:00:48] Right. I’ll try and I you know I have to do that in my writing but sometimes I cheat – because I’m not motivated. If we’re doing it so we won’t offend Dr. Parkinson, he’s long dead. He published his essay on the shaking palsy in 1817, so I’m sure he’s not going to mind.
[00:01:03] I don’t know what’s behind this trend. Maybe one of our listeners can inform us.
[00:01:07] I think it is just that it’s it’s just it’s not an ownership thing. Well anyway we mentioned in the intro that Parkinson disease is the second most common neurodegenerative disease in the U.S. We should probably explain what a neurodegenerative disease is.
[00:01:25] Well – it’s I mean the name is maybe a little self-evident – but the most common neuro degenerative disease is Alzheimer’s by the way no Alzheimer.
[00:01:35] And what’s happening in both Parkinson’s disease and Alzheimer disease – Gee that sounds so wrong – is it certain types of cells in the brain are dying.
[00:01:43] But not the same ones right. Alzheimer – No S – is caused by the death of different types of cells in the brain than Parkinson disease.
[00:01:50] Right. If you were to do a brain biopsy of people with Parkinson disease it would have distinct patterns under the microscope compared to normal brains or brains from patients with other neurodegenerative disorders.
[00:02:01] So for PD – which is how I’m going – from here on. Parkinson Disease PD the cells that are dying are the ones located in the part of the brain called the substantia Nigra. And these cells produce dopamine which is a neurotransmitter chemical messenger in the brain.
[00:02:17] So patients with Parkinson disease I’m going to keep practicing saying that without the S – patients with Parkinson’s disease. No patience with Parkinson disease end up with a deficiency of dopamine.
[00:02:28] Right. So first line medications like Sinemet or levodopa/carbidopa. They are basically oral forms of dopamine that go directly to the brain. By the way, we don’t need to do a brain biopsy to diagnose PD, it’s done clinically based on signs and symptoms.
[00:02:44] Thank goodness I’ve ordered a brain biopsy only once in my career and it sadly did not help diagnostically-speaking.
[00:02:50] That’s so hard.
[00:02:52] I don’t want to ever do it again.
[00:02:54] So as far as signs and symptoms go, PD has been described as a movement disorder because the most well-known symptom is a tremor. The resting pill rolling tremor that I’m sure lots of our listeners have seen before.
[00:03:05] Yes. But these patients have other movement problems and the mnemonic TRAP is a good way to remember them.
[00:03:13] Yes. So T stands for tremor, R stands for rigidity.
[00:03:17] What we mean here is that the muscles get really stiff. It’s often described as a cogwheel rigidity which refers to this sort of stop and go effect a patient will have when they’re doing range of motion exercises.
[00:03:30] OK so T R – A is next and refers to akinetic. Akinetic means slowed muscle movement. PD patients will move very slowly when they try to do anything like walk, pick something up, turn around, any kind of activity really.
[00:03:46] And then finally, P, which stands for postural instability. The classic posture for Parkinson’s disease is that they are flexed at the waist and they have this sort of shuffling gait.
[00:03:57] Sometimes they look like hey’re sort of falling forward whenever they walk.
[00:04:00] And sometimes they do fall forward. And there’s lots of other physical exam findings that are helpful if you’re trying to make a diagnosis of Parkinson’s disease.
[00:04:10] Patients will develop a really soft voice.
[00:04:13] Or they’ll have a flattened affect, meaning they won’t really show any facial emotion even though they may be feeling it inside.
[00:04:20] Right. Also if you get these patients to write, they’ll have something called micrographic where their script is really really small.
[00:04:26] Yeah you can see how these things can be very debilitating. It can make any activity difficult – just dressing yourself or cooking or walking can become incredibly challenging.
[00:04:36] Yeah. And unfortunately Parkinson disease patients also have non-motor symptoms.
[00:04:41] Meaning the problems with other than tremors.
[00:04:45] Right. Yes sometimes their autonomic nervous system doesn’t work very well. The autonomic nervous system is the part of the nervous system that controls body functions like heart rate, blood pressure, gut motility that kind of thing. So some patients will have problems with very low blood pressure or constipation or impotence.
[00:05:04] And there’s kind of a grab bag of other problems. Some people lose their sense of smell, develop sleep disorders, and have problems with depression.
[00:05:13] And about 40 percent of patients will develop cognitive decline and even dementia – usually late in the course of the disease though.
[00:05:20] Yeah. Actually a cognitive decline might start earlier than we once thought. Clinicians are starting to change their thinking about this.
[00:05:27] And then some patients develop Parkinson’s disease psychosis.
[00:05:31] OK a quick definition here. A psychosis is characterized by delusions or auditory or visual hallucinations and in PD patients, we used to think the psychosis was caused by the drugs we used to treat these patients. But we now know the psychosis is part of the disease itself.
[00:05:49] And as you would expect in patients with psychosis they do way worse than patients without.
[00:05:54] And don’t forget the burden on care givers. It’s just extreme. If you talk to families, go to support groups, read postings and online chat rooms, these people are facing incredible challenges caring for their loved one. It can be tragic for them.
[00:06:07] So the big question is what causes Parkinson’s disease?
[00:06:11] Well the quick answer we don’t know. But interestingly enough people who smoke or drink a lot of coffee don’t get it as often.
[00:06:17] Really – coffee and nicotine that might be protective? That’s not a good reason to start smoking but drinking coffee that’s not a problem.
[00:06:25] Researchers are pretty sure that it is a combination of inherited and environmental causes.
[00:06:30] I mean the underlying cause of Parkinson. Well here’s a disturbing development.
[00:06:35] Oh no.
[00:06:35] A study in the journal JAMA Journal of American Medical Association neurology, came out in June of last year and suggested that the incidence of Parkinson disease has been increasing over the past 30 years.
[00:06:49] But just in men right?
[00:06:50] Right. So what they did is track the incidence of Parkinson’s in Olmsted County Minnesota from January of 1976 to December of 2005.
[00:07:01] Did we forget to mention that PD is more common in men than women. Yes we did. OK. So it is more common in men than women – by a lot of the incidence and is 1.5 times greater than women. OK so anyway what they find in this study.
[00:07:15] That the incidence of Parkinson disease is increasing in men but not in women as as you said. It went from thirty six point eight per 100000 in 1976 to 56 per one hundred thousand in 2005.
[00:07:28] What’s the difference between incidence and prevalence?
[00:07:32] Prevalence is the proportion of cases in a population at a specific point in time. I remember it because of all the P’s and incidence rate of occurrence.
[00:07:43] Right. So like you would say incidence like this many new cases over a certain period of time.
[00:07:48] Yeah. OK thank you for that. So back to Olmsted County. This is just one little county in Minnesota, probably full of white people of Scandinavian extraction. Hard to apply that to the U.S. population as a whole.
[00:08:00] All right. That’s true. And some people feel that clinicians in the 70s weren’t aware of Parkinson’s disease as they are now. So a lot of cases might have been missed but if the study is true, if bigger population studies confirm this finding then what could be going on here.
[00:08:15] No idea. Some people have mentioned the decrease in smoking among men over the past few decades because men who smoke have a lower incidence of Parkinson’s.
[00:08:23] That’s a cruel joke. I don’t know. I wonder if we have any historical data about Parkinson’s disease.
[00:08:28] Well it wasn’t even described at all until 1817 so I doubt that.
[00:08:33] Maybe it’s an industrialized world disease.
[00:08:36] Or maybe people are living long enough to develop it instead of dying of the plague or getting pole-axed by a marauding Viking.
[00:08:43] That could be but as far as causes of the disease go the best we’ve done is develop a list of associations.
[00:08:50] Right. Like there seems to be an association between PD and pesticide exposure.
[00:08:55] And patients with hepatitis B and hepatitis C also have increased incidence of Parkinson disease.
[00:09:00] And a recent study came out showing an association between the use of the drug metformin, which is used for diabetes, and PD.
[00:09:07] So this to me is particularly frightening. Metformin, also known as Glucophage, is an oral medication considered first line therapy for people with type 2 diabetes. It’s been around forever. And considering the millions of people with diabetes in this country and the millions of people on metformin this could have huge implications.
[00:09:26] Well don’t get too worked up yet about that. None of these studies are randomized controlled trials. They can’t show causation, just association. But what I find most interesting about research into the possible causes of PD is the Brock hypothesis.
[00:09:41] Yes me too. Very fascinating. So the hypothesis is that some unknown pathogen, maybe a prion, is ingested and then travels from the nerves of the stomach or the intestine up to the brain.
[00:09:54] And the reason researchers came up with this theory is because they noticed patients who had a vagotomy are much less likely to get pd than patients who didn’t.
[00:10:03] So just so everybody understands a vagotomy is where the vagus nerve is surgically severed. This is the nerve that enervates the entire gut and surgeons used to do this in patients who had severe stomach ulcers. It’s a pretty drastic treatment and we don’t do vagotomies anymore, but there might be a clue to the pathogenesis of Parkinson disease. I’m getting better at that Parkinso disease.
[00:10:26] The bottom line though is that we don’t yet know what causes the diseas. The incidence or prevalence or both might be on the rise and treatment is not curative.
[00:10:34] That’s true. We haven’t talked much about treatment other than to mention levodopa/carbidopa. But no matter what form of treatment people are on, it just treats the symptoms it doesn’t treat the disease – it does not.
[00:10:46] And the disease always progresses.
[00:10:48] Now people might live longer because their symptoms are better controlled and they don’t fall as much or sustain life threatening trauma or some other complication. But we have no cure and nothing slows the progression.
[00:10:58] I’m hopeful though so many people are working on this problem and the payoff for success is so high. I’m sure we’ll find some answers soon.
[00:11:06] So that’s our show for today. If you liked what you heard. Leave us a review on iTunes. And until then.
[00:11:11] Drink more coffee.
[00:11:13] But don’t start smoking please.
[00:11:15] It’s not worth it.
[00:11:17] Maybe we should aleft the whole thing about smoking out. I don’t want to inspire anyone.
[00:11:20] Well no I think it’s. I mean we’re we’re evidence we’re not about leaving out stuff.
[00:11:25] OK good point. Thank you Amy. You are keeping me on the straight narrow.
[00:11:28] That’s right.
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