In my previous post, we briefly reviewed the results of the phase II double-blind, randomised clinical trial of Exenatide in Parkinson’s disease. The study indicates a statistically significant effect on motor symptom scores after being treated with the drug.
Over the last few days, there have been many discussions about the results, what they mean for the Parkinson’s community, and where things go from here, which have led to further questions.
In this post I would like to address several matters that have arisen which I did not discuss in the previous post, but that I believe are important.
I found out about the Exenatide announcement – via whispers online – on the afternoon of the release. And it was in a mad rush when I got home that night that I wrote up the post explaining what Exenatide is. I published the post the following evening however because I could not access the research report from home (seriously guys, biggest finding in a long time and it’s not OPEN ACCESS?!?!?) and I had to wait until I got to work the next day to actually view the publication.
I was not really happy with the rushed effort though and decided to follow up that post. In addition, there has been A LOT of discussion about the results over the weekend and I thought it might be good to bring aspects of those different discussion together here. The individual topics are listed below, in no particular order of importance:
1. Size of the effect
There are two considerations here.
Firstly, there have been many comments about the actual size of the effect in the results of the study itself. When people have taken a deeper look at the findings, they have come back with questions regarding those findings.
And second, there have also been some comments about the size of the effect that this result has already had on the Parkinson’s community, which has been considerable (and possibly disproportionate to the actual result).
The size of the effect in the results
The results of the study suggested that Exenatide had a positive effect on the motor-related symptoms of Parkinson’s over the course of the 60 week trial. This is what the published report says, it is also what all of the media headlines have said, and it sounds really great right?
The main point folks keep raising, however, is that the actual size of the positive effect is limited to just the motor features of Parkinson’s disease. If one ignores the Unified Parkinson’s Disease Rating Scale (UPDRS) motor scores and focuses on the secondary measures, there isn’t much to talk about. In fact, there were no statistically significant differences in any of the secondary outcome measures. These included:
For many people diagnosed with Parkinson’s disease, one of the scariest prospects of the condition that they face is the possibility of developing dyskinesias.
Dyskinesias are involuntary movements that can develop after long term use of the primary treatment of Parkinson’s disease: Levodopa
In todays post I discuss one experimental strategy for dealing with this debilitating aspect of Parkinson’s disease.
Dyskinesia. Source: JAMA Neurology
There is a normal course of events with Parkinson’s disease (and yes, I am grossly generalising here).
First comes the shock of the diagnosis.
This is generally followed by the roller coaster of various emotions (including disbelief, sadness, anger, denial).
Then comes the period during which one will try to familiarise oneself with the condition (reading books, searching online, joining Facebook groups), and this usually leads to awareness of some of the realities of the condition.
One of those realities (especially for people with early onset Parkinson’s disease) are dyskinesias.
What are dyskinesias?
Dyskinesias (from Greek: dys – abnormal; and kinēsis – motion, movement) are simply a category of movement disorders that are characterised by involuntary muscle movements. And they are certainly not specific to Parkinson’s disease.
As I have suggested in the summary at the top, they are associated in Parkinson’s disease with long-term use of Levodopa (also known as Sinemet or Madopar).
Sinemet is Levodopa. Source: Drugs
A new research report looking at the use of cholesterol-reducing drugs and the risk of developing Parkinson’s disease has just been published in the scientific journal Movement disorders.
The results of that study have led to some pretty startling headlines in the media, which have subsequently led to some pretty startled people who are currently taking the medication called statins.
In todays post, we will look at what statins are, what the study found, and discuss what it means for our understanding of Parkinson’s disease.
Cholesterol forming plaques (yellow) in the lining of arteries. Source: Healthguru
Cholesterol gets a lot of bad press.
Whether it’s high and low, the perfect balance of cholesterol in our blood seems to be critical to our overall health and sense of wellbeing. At least that is what we are constantly being told this by media and medical professionals alike.
But ask yourself this: Why? What exactly is cholesterol?
Good question. What is cholesterol?
Cholesterol (from the Greek ‘chole‘- bile and ‘stereos‘ – solid) is a waxy substance that is circulating our bodies. It is generated by the liver, but it is also found in many foods that we eat (for example, meats and egg yolks).
The chemical structure of Cholesterol. Source: Wikipedia
Cholesterol falls into one of three major classes of lipids – those three classes of lipids being Triglycerides, Phospholipids and Steroids (cholesterol is a steroid). Lipids are major components of the cell membranes and thus very important. Given that the name ‘lipids’ comes from the Greek lipos meaning fat, people often think of lipids simply as fats, but fats more accurately fall into just one class of lipids (Triglycerides).
Like many fats though, cholesterol dose not dissolve in water. As a result, it is transported within the blood system encased in a protein structure called a lipoprotein.
The structure of a lipoprotein; the purple C inside represents cholesterol. Source: Wikipedia
Lipoproteins have a very simple classification system based on their density:
- very low density lipoprotein (VLDL)
- low density lipoprotein (LDL)
- intermediate density lipoprotein (IDL)
- high density lipoprotein (HDL).
Now understand that all of these different types of lipoproteins contain cholesterol, but they are carrying it to different locations and this is why some of these are referred to as good and bad.
The first three types of lipoproteins carry newly synthesised cholesterol from the liver to various parts of the body, and thus too much of this activity would be bad as it results in an over supply of cholesterol clogging up different areas, such as the arteries.
LDLs, in particular, carry a lot of cholesterol (with approximately 50% of their contents being cholesterol, compared to only 20-30% in the other lipoproteins), and this is why LDLs are often referred to as ‘bad cholesterol’. High levels of LDLs can result in atherosclerosis (or the build-up of fatty material inside your arteries).
Progressive and painless, atherosclerosis develops as cholesterol silently and slowly accumulates in the wall of the artery, in clumps that are called plaques. White blood cells stream in to digest the LDL cholesterol, but over many years the toxic mess of cholesterol and cells becomes an ever enlarging plaque. If the plaque ever ruptures, it could cause clotting which would lead to a heart attack or stroke.
So yeah, some lipoproteins can be considered bad.
HDLs, on the other hand, collects cholesterol and other lipids from cells around the body and take them back to the liver. And this is why HDLs are sometimes referred to as “good cholesterol” because higher concentrations of HDLs are associated with lower rates of atherosclerosis progression (and hopefully regression).
But why is cholesterol important?
While cholesterol is usually associated with what is floating around in your bloodstream, it is also present (and very necessary) in every cell in your body. It helps to produce cell membranes, hormones, vitamin D, and the bile acids that help you digest fat.
It is particularly important for your brain, which contains approximately 25 percent of the cholesterol in your body. Numerous neurodegenerative conditions are associated with cholesterol disfunction (such as Alzheimer’s disease and Huntington’s disease – Click here for more on this). In addition, low levels of cholesterol is associated with violent behaviour (Click here to read more about this).
Are there any associations between cholesterol and Parkinson’s disease?
The associations between cholesterol and Parkinson’s disease is a topic of much debate. While there have been numerous studies investigating cholesterol levels in blood in people with Parkinson’s disease, the results have not been consistent (Click here for a good review on this topic).
Rather than looking at cholesterol directly, a lot of researchers have chosen to focus on the medication that is used to treat high levels of cholesterol – a class of drugs called statins.
Title: Prospective study of statin use and risk of Parkinson disease.
Authors: Gao X, Simon KC, Schwarzschild MA, Ascherio A.
Journal: Arch Neurol. 2012 Mar;69(3):380-4.
PMID: 22410446 (This article is OPEN ACCESS if you would like to read it)
In this study the researchers conduced a prospective study involving the medical details of 38 192 men and 90 874 women from two huge US databases: the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS).
NHS study was started in 1976 when 121,700 female registered nurses (aged 30 to 55 years) completed a mailed questionnaire. They provided an overview of their medical histories and health-related behaviours. The HPFS study was established in 1986, when 51,529 male health professionals (40 to 75 years) responded to a similar questionnaire. Both the NHS and the HPFS send out follow-up questionnaires every 2 years.
By analysing all of that data, the investigators found 644 cases of Parkinson’s disease (338 women and 306 men). They noticed that the risk of Parkinson’s disease was approximately 25% lower among people currently taking statins when compared to people not using statins. And this association was significant in statin users younger than 60 years of age (P = 0.02).
What are statins?
Also known as HMG-CoA reductase inhibitors, statins are a class of drug that inhibits/blocks an enzyme called 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase.
HMG-CoA reductase is the key enzyme regulating the production of cholesterol from mevalonic acid in the liver. By blocking this process statins help lower the total amount of cholesterol available in your bloodstream.
Statins are used to treat hypercholesterolemia (also called dyslipidemia) which is high levels of cholesterol in the blood. And they are one of the most widely prescribed classes of drugs currently available, with approximately 23 percent of adults in the US report using statin medications (Source).
Now, while the study above found an interesting association between statin use and a lower risk of Parkinson’s disease, the other research published on this topic has not been very consistent. In fact, a review in 2009 found a significant associations between statin use and lower risk of Parkinson’s disease was observed in only two out of five prospective studies (Click here to see that review).
New research published this week has attempted to clear up some of that inconsistency, by starting with a huge dataset and digging deep into the numbers.
So what new research has been published?
Title: Statins may facilitate Parkinson’s disease: Insight gained from a large, national claims database
Authors: Liu GD, Sterling NW, Kong L, Lewis MM, Mailman RB, Chen H, Leslie D, Huang X
Journal: Movement Disorder, 2017 Jun;32(6):913-917.
Using the MarketScan Commercial Claims and Encounters database which catalogues the healthcare use and medical expenditures of more than 50 million employees and their family members each year, the researcher behind that study identified 30,343,035 individuals that fit their initial criteria (that being “all individuals in the database who had 1 year or more of continuous enrolment during January 1, 2008, to December 31, 2012, and were 40 years of age or older at any time during their enrolment”). From this group, the researcher found a total of 21,599 individuals who had been diagnosed with Parkinson’s disease.
In their initial analysis, the researchers found that Parkinson’s disease was positively associated with age, male gender, hypertension, coronary artery disease, and usage of cholesterol-lowering drugs (both statins and non-statins). The condition was negatively associated with hyperlipidemia (or high levels of cholesterol). This result suggests not only that people with higher levels of cholesterol have a reduced chance of developing Parkinson’s disease, but taking medication to lower cholesterol levels may actually increase ones risk of developing the condition.
One interesting finding in the data was the effect that different types of statins had on the association.
Statins can be classified into two basic groups: water soluble (or hydrophilic) and lipid soluble (or lipophilic) statins. Hydrophilic molecule have more favourable interactions with water than with oil, and vice versa for lipophilic molecules.
Hydrophilic vs lipophilic molecules. Source: Riken
Water soluble (Hydrophilic) statins include statins such as pravastatin and rosuvastatin; while all other available statins (eg. atorvastatin, cerivastatin, fluvastatin, lovastatin and simvastatin) are lipophilic.
In this new study, the researchers found that the association between statin use and increased risk of developing Parkinson’s disease was more pronounced for lipophilic statins (a statistically significant 58% increase – P < 0.0001), compared to hydrophilic statins (a non-significant 19% increase – P = 0.25). One possible explanation for this difference is that lipophilic statins (like simvastatin and atorvastatin) cross the blood-brain barrier more easily and may have more effect on the brain than hydrophilic ones.
The investigators also found that this association was most robust during the initial phase of statin treatment. That is to say, the researchers observed a 82% in risk of PD within 1 year of having started statin treatment, and only a 37% increase five years after starting statin treatment.; P < 0.0001). Given this finding, the investigators questioned whether statins may be playing a facilitatory role in the development of Parkinson’s disease – for example, statins may be “unmasking” the condition during its earliest stages.
So statins are bad then?
Can I answer this question with a diplomatic “I don’t know”?
It is difficult to really answer that question based on the results of just this one study. This is mostly because this new finding is in complete contrast to a lot of experimental research over the last few years which has shown statins to be neuroprotective in many models of Parkinson’s disease. Studies such as this one:
Title: Simvastatin inhibits the activation of p21ras and prevents the loss of dopaminergic neurons in a mouse model of Parkinson’s disease.
Authors: Ghosh A, Roy A, Matras J, Brahmachari S, Gendelman HE, Pahan K.
Journal: J Neurosci. 2009 Oct 28;29(43):13543-56.
PMID: 19864567 (This study is OPEN ACCESS if you would like to read it)
In this study, the researchers found that two statins (pravastatin and simvastatin – one hydrophilic and one lipophilic, respectively) both exhibited the ability to suppress the response of helper cells in the brain (called microglial) in a neurotoxin model of Parkinson’s disease. This microglial suppression resulted in a significant neuroprotective effect on the dopamine neurons in these animals.
Another study found more Parkinson’s disease relevant effects from statin treatment:
TItle: Lovastatin ameliorates alpha-synuclein accumulation and oxidation in transgenic mouse models of alpha-synucleinopathies.
Authors: Koob AO, Ubhi K, Paulsson JF, Kelly J, Rockenstein E, Mante M, Adame A, Masliah E.
Journal: Exp Neurol. 2010 Feb;221(2):267-74.
PMID: 19944097 (This study is OPEN ACCESS if you would like to read it)
In this study, the researchers treated two different types of genetically engineered mice (both sets of mice produce very high levels of alpha synuclein – the protein closely associated with Parkinson’s disease) with a statin called lovastatin. In both groups of alpha synuclein producing mice, lovastatin treatment resulted in significant reductions in the levels of cholesterol in their blood when compared to the saline-treated control mice. The treated mice also demonstrated a significant reduction in levels of alpha synuclein clustering (or aggregation) in the brain than untreated mice, and this reduction in alpha synuclein accumulation was associated with a lessening of pathological damage in the brain.
So statins may not be all bad?
One thing many of these studies fail to do is differentiate between whether statins are causing the trouble (or benefit) directly or whether simply lowering cholesterol levels is having a negative impact. That is to say, do statins actually do something else? Other than lowering cholesterol levels, are statins having additional activities that could cause good or bad things to happen?
The recently published study we are reviewing in this post suggested that non-statin cholesterol medication is also positively associated with developing Parkinson’s disease. Thus it may be that statins are not bad, but rather the lowering of cholesterol levels that is. This raises the question of whether high levels of cholesterol are delaying the onset of Parkinson’s disease, and one can only wonder what a cholesterol-based process might be able to tell us about the development of Parkinson’s disease.
If the findings of this latest study are convincingly replicated by other groups, however, we may need to reconsider the use of statins not in our day-to-day clinical practice. At the very least, we will need to predetermine which individuals may be more susceptible to developing Parkinson’s disease following the initiation of statin treatment. It would actually be very interesting to go back to the original data set of this new study and investigate what addition medical features were shared between the people that developed Parkinson’s disease after starting statin treatment. For example, were they all glucose intolerant? One would hope that the investigators are currently doing this.
Are Statins currently being tested in the clinic for Parkinson’s disease?
(Oh boy! Tough question) Yes, they are.
There is currently a nation wide study being conducted in the UK called PD STAT.
Is this dangerous given the results of the new research study?
(Oh boy! Even tougher question!)
Again, we are asking this question based on the results of one recent study. Replication with independent databases is required before definitive conclusions can be made.
There have, however, been previous clinical studies of statins in neurodegenerative conditions and these drugs have not exhibited any negative effects (that I am aware of). In fact, a clinical trial for multiple sclerosis published in 2014 indicated some positive results for sufferers taking simvastatin:
Title: Effect of high-dose simvastatin on brain atrophy and disability in secondary progressive multiple sclerosis (MS-STAT): a randomised, placebo-controlled, phase 2 trial.
Authors: Chataway J, Schuerer N, Alsanousi A, Chan D, MacManus D, Hunter K, Anderson V, Bangham CR, Clegg S, Nielsen C, Fox NC, Wilkie D, Nicholas JM, Calder VL, Greenwood J, Frost C, Nicholas R.
Journal: Lancet. 2014 Jun 28;383(9936):2213-21.
PMID: 24655729 (This article is OPEN ACCESS if you would like to read it)
In this double-blind clinical study (meaning that both the investigators and the subjects in the study were unaware of which treatment was being administered), 140 people with multiple sclerosis were randomly assigned to receive either the statin drug simvastatin (70 people; 40 mg per day for the first month and then 80 mg per day for the remainder of 18 months) or a placebo treatment (70 people).
Patients were seen at 1, 6, 12, and 24 months into the study, with telephone follow-up at months 3 and 18. MRI brain scans were also made at the start of the trial, and then again at 12 months and 25 months for comparative sake.
The results of the study indicate that high-dose simvastatin was well tolerated and reduced the rate of whole-brain shrinkage compared with the placebo treatment. The mean annualised shrinkage rate was significantly lower in patients in the simvastatin group. The researchers were very pleased with this result and are looking to conduct a larger phase III clinical trial.
Other studies have not demonstrated beneficial results from statin treatment, but they have also not observed a worsening of the disease conditions:
Title: A randomized, double-blind, placebo-controlled trial of simvastatin to treat Alzheimer disease.
Authors:Sano M, Bell KL, Galasko D, Galvin JE, Thomas RG, van Dyck CH, Aisen PS.
Journal: Neurology. 2011 Aug 9;77(6):556-63.
PMID: 21795660 (This article is OPEN ACCESS if you would like to read it)
In this study, the investigators recruited a total of 406 individuals were mild to moderate Alzheimer’s disease, and they were randomly assigned to two groups: 204 to simvastatin (20 mg/day, for 6 weeks then 40 mg per day for the remainder of 18 months) and 202 to placebo control treatment. While Simvastatin displayed no beneficial effects on the progression of symptoms in treated individuals with mild to moderate Alzheimer’s disease (other than significantly lowering of cholesterol levels), the treatment also exhibited no effect on worsening the disease.
So what does it all mean?
Research investigating cholesterol and its association with Parkinson’s disease has been going on for a long time. This week a research report involving a huge database was published which indicated that using cholesterol reducing medication could significantly increase one’s risk of developing Parkinson’s disease.
These results do not mean that someone being administered statins is automatically going to develop Parkinson’s disease, but – if the results are replicated – it may need to be something that physicians should consider before prescribing this class of drug.
Whether ongoing clinical trials of statins and Parkinson’s disease should be reconsidered is a subject for debate well above my pay grade (and only if the current results are replicated independently). It could be that statin treatment (or lowering of cholesterol) may have an ‘unmasking’ effect in some individuals, but does this mean that any beneficial effects in other individuals should be discounted? If preclinical data is correct, for example, statins may reduce alpha synuclein clustering in some people which could be beneficial in Parkinson’s.
As we have said above, further research is required in this area before definitive conclusions can be made. This is particularly important given the inconsistencies of the previous research results in the statin and Parkinson’s disease field of investigation.
EDITORIAL NOTE: The information provided by the SoPD website is for information and educational purposes only. Under no circumstances should it ever be considered medical or actionable advice. It is provided by research scientists, not medical practitioners. Any actions taken – based on what has been read on the website – are the sole responsibility of the reader. Any actions being contemplated by readers should firstly be discussed with a qualified healthcare professional who is aware of your medical history. While some of the information discussed in this post may cause concern, please speak with your medical physician before attempting any change in an existing treatment regime.
The banner for today’s post was sourced from HarvardHealth
Last week a new piece of Parkinson’s disease research has been widely discussed in the media.
It involves Hepatitis – the viral version of it at least.
In today’s post we will review the research and discuss what it may mean for Parkinson’s disease.
A lewy body (brown with a black arrow) inside a cell. Source: Cure Dementia
A definitive diagnosis of Parkinson’s disease can only be made at the postmortem stage with an examination of the brain. Until that moment, all cases of Parkinson’s disease are ‘suspected’.
Critical to that postmortem diagnosis is the presence of circular shaped, dense clusters of proteins, called Lewy bodies (see the image above for a good example).
What causes Lewy bodies? We don’t know, but many people have theories.
This is Friedrich Heinrich Lewy (1885-1950).
Friedrich Lewy. Source: Lewy Body Society
As you can probably guess, Friedrich was the first to discover the ‘Lewy body’. His finding came by examining the brains of 85 people who died with Parkinson’s disease between 1908 – 1923.
In 1931, Friedrich Lewy read a paper at the International Congress of Neurology in Bern. During that talk he noted the similarities between the circular inclusions (called ‘negri bodies’) in the brains of people who suffered from rabies and his own Lewy bodies (observed in Parkinson’s disease).
A Negri body in a cell affected by rabies (arrow). Source: Nethealthbook
Given the similarities, Lewy proposed a viral cause for Parkinson’s disease.
Now, the idea that Parkinson’s disease could have a viral component has existed for a long time – even before Lewy made his conclusion. As we have previous mentioned, theories of viral causes for Parkinson’s have been circulating ever since the 1918 flu pandemic (Click here to read our post on this topic).
An example of post-encephalitic Parkinsonism. Source: Baillement
About the same time as the influenza virus was causing havoc around the world, another condition began to appear called ‘encephalitis lethargica‘ (also known as post-encephalitic Parkinsonism). This disease left many of the victims in a statue-like condition, both motionless and speechless – similar to Parkinson’s disease. Initially, it was assumed that the influenza virus was the causal factor, but more recent research has left us not so sure anymore.
Since then there, however, has been additional bits of evidence suggesting a viral role in Parkinson’s disease. Such as this report:
Title: Highly pathogenic H5N1 influenza virus can enter the central nervous system and induce neuroinflammation and neurodegeneration.
Author: Jang H, Boltz D, Sturm-Ramirez K, Shepherd KR, Jiao Y, Webster R, Smeyne RJ.
Journal: Proc Natl Acad Sci U S A. 2009 Aug 18;106(33):14063-8.
The researchers in this study found that when they injected the highly infectious H5N1 influenza virus into mice, the virus progressed from the periphery (outside the brain) into the brain itself, where it induced Parkinson’s disease-like symptoms. The virus also caused a significant increase in the accumulation of the Parkinson’s associated protein Alpha Synuclein. Importantly, they witnessed the loss of dopamine neurons in the midbrain of the mice 60 days after resolution of the infection – that cell loss resembling what is observed in the brains of people with Parkinson’s disease.
The Parkinson’s associated protein alpha synuclein has also recently demonstrated anti-viral properties:
Title: Alpha-Synuclein Expression Restricts RNA Viral Infections in the Brain.
Authors: Beatman EL, Massey A, Shives KD, Burrack KS, Chamanian M, Morrison TE, Beckham JD.
Journal: J Virol. 2015 Dec 30;90(6):2767-82. doi: 10.1128/JVI.02949-15.
PMID: 26719256 (This article is OPEN ACCESS if you would like to read it)
David Beckham (not the football player) and his research colleagues introduced West nile virus to brain cells grown in cell culture and they observed an increase in alpha synuclein production. They also found that the brains of people with West nile infections had increased levels of alpha synuclein.
The researchers then injected West Nile virus into both normal mice and genetically engineered mice (which produced no alpha synuclein) and they found that the genetically engineered mice which produced no alpha synuclein died quicker than the normal mice. They reported that there was an almost 10x increase in viral production in the genetically engineered mice. This suggested to them that alpha synuclein may be playing a role in protecting cells from viral infections.
Interesting, but what about this new data involving Hepatitis?
Yes, indeed. Let’s move on.
Wait a minute, what is Hepatitis exactly?
The name Hepatitis comes from the Greek: Hepat – liver; and itis – inflammation, burning sensation. Thus – as the label suggests – Hepatitis is inflammation of liver tissue.
Hepatitis and the liver. Source: HealthandLovepage
It can be caused by infectious agents (such as viruses, bacteria, and parasites), metabolic changes (induced by drugs and alcohol), or autoimmune/genetic causes (involving a genetic predisposition).
The most common cause of hepatitis is viral.
There are five main types of viral hepatitis (labelled A, B, C, D, and E). Hepatitis A and E are mainly spread by contaminated food and water. Both hepatitis B and hepatitis C are commonly spread through infected blood (though Hepatitis B is mainly sexually transmitted). Curiously, Hepatitis D can only infect people already infected with hepatitis B.
Hepatitis A, B, and D are preventable via the use of immunisation. A vaccine for hepatitis E has been developed and is licensed in China, but is not yet available elsewhere
Hepatitis C, however, is different.
There is currently no vaccine for it, mainly because the virus is highly variable between strains and the virus mutates very quickly, making an effective vaccine a difficult task. A number of vaccines under development (Click here for more on this).
What is known about Hepatitis C and the brain?
Quite a bit.
Similar to HIV (which we discussed in a previous post), the hepatitis C virus (HCV) enters the brain via infected blood-derived macrophage cells. In the brain, it is hosted by microglial cells, which results in altered functioning of those microglial cells. This causes problems for neuronal cells – including dopamine neurons. For example, people infected with HCV have reduced dopamine transmission, based on brain imaging studies (Click here and here for more on this result).
Have there been connections between hepatitis C virus and Parkinson’s disease before?
Title: Hepatitis C virus infection: a risk factor for Parkinson’s disease.
Authors: Wu WY, Kang KH, Chen SL, Chiu SY, Yen AM, Fann JC, Su CW, Liu HC, Lee CZ, Fu WM, Chen HH, Liou HH.
Journal: J Viral Hepat. 2015 Oct;22(10):784-91.
The researchers in this study used data collected from a community-based screening program in north Taiwan which involved 62,276 people. The World Health Organisation (WHO) estimates that the prevalence of hepatitis C viral infection worldwide is approximately 2.2–3%, representing 130–170 million people. Taiwan is a high risk area for hepatitis, with antibodies for hepatitis viruses in Taiwan present in 4.4% in the general population (Source).
The researchers found that the significant association between hepatitis C viral infections and Parkinson’s disease – that is to say, a previous infection of hepatitis C increased the risk of developing Parkinson’s disease (by 40%). The researchers then looked at what the hepatitis C and B viral infections do to dopamine neurons growing in cell culture. They found that hepatitis C virus induced 60% dopaminergic cell death, while hepatitis B had no effect.
This study was followed up a few months later, by a second study suggesting an association between Hepatitis C virus and Parkinson’s disease:
Title: Hepatitis C virus infection as a risk factor for Parkinson disease: A nationwide cohort study.
Authors: Tsai HH, Liou HH, Muo CH, Lee CZ, Yen RF, Kao CH.
Journal: Neurology. 2016 Mar 1;86(9):840-6.
The researchers in this study wanted to investigate whether hepatitis C could be a risk factor for Parkinson’s disease. They did this by analyzing data from 2000-2010 drawn again from the Taiwan National Health Insurance Research Database.
The database included 49,967 people with either hepatitis B, hepatitis C or both, in addition to 199,868 people without hepatitis. During the 12 year period, 270 participants who had a history of hepatitis developed Parkinson’s disease (120 still had hepatitis C). This compared with 1,060 participants who were free of hepatitis, but went on to develop Parkinson’s disease.
When the researchers controlled for potentially confounding factors (such as age, sex, etc), the researchers found participants with hepatitis C had a 30% greater risk of developing Parkinson’s disease than the controls.
So if this has been demonstrated, why is this new study last week so important?
The answer is very simple: This study is not based on statistics from Taiwan – this new study has found the same result from a new population.
Title: Viral hepatitis and Parkinson disease: A national record-linkage study.
Authors: Pakpoor J, Noyce A, Goldacre R, Selkihova M, Mullin S, Schrag A, Lees A, Goldacre M.
Journal: Neurology. 2017 Mar 29. [Epub ahead of print]
These researchers used the English National Hospital Episode Statistics database and linked it to mortality data collected from 1999 till 2011. They too have found a strong association between hepatitis C and Parkinson’s disease (standardized rate ratio 1.51, 95% CI 1.18–1.9).
Curiously (and different from the previous studies), the researchers in this study also found a strong association for hepatitis B and Parkinson’s disease (standardized rate ratio 1.76, 95% CI 1.28–2.37). And these associations appear to be specific to Hepatitis B and C, as the investigators did not find any association between autoimmune hepatitis, chronic hepatitis, or HIV.
One important caveat with this new study, however, is that the authors could not
control for lifestyle factors (such as smoking or alcohol consumption). In addition, their system of linking medical records may underestimate the numbers of patients with
Parkinson’s disease as it would not take into account people with Parkinson’s disease who do not seek medical advice or those who are misdiagnosed (given a wrong diagnosis – it does happen!).
Regardless of these cautionary notes, the results still add to the accumulating evidence of an association between the virus that causes Hepatitis and the neurodegenerative condition of Parkinson’s disease.
But what about those people with Parkinson’s disease who have never had Hepatitis?
Yeah, this is a good question.
But there is a rather uncomfortable answer to it.
Here’s the rub: “Approximately 70%–80% of people with acute Hepatitis C do not have any symptoms” (Source: Centre for Disease Control). That is to say, the majority of people infected with the Hepatitis C virus will not be aware that they are infected. Some of those people who are infected may think that they have a case of the flu (HCV symptoms include fever, fatigue, loss of appetite,…), while others will simply not display any symptoms at all.
So many people with Parkinson’s disease may have had HCV, but never been aware of it.
And this is the really difficult part of researching the causal elements of Parkinson’s disease.
The responsible agent may actually leave little or no sign that they were ever present. For a long time, people have suggested that Parkinson’s disease is caused by a thief in the night – some agent that comes in, causes a problem and disappears without detection.
Perhaps Hepatitis is that thief.
But hang on a second, 60–70% of HCV infected people will go on to develop chronic liver disease (Source). Do people with Parkinson’s disease have liver issue?
Umm, well actually, in some cases: yes.
There have been studies of liver function in Parkinson’s disease where abnormalities have been found (Click here for more on this). And dopamine cell dysfunction has been seen in people with cirrhosis issues (Click here for more on this). In fact, the prevalence of Parkinsonism in people with cirrhosis has been estimated to be as high as 20% (and Click here for more on that).
So what are we saying? Hepatitis causes Parkinson’s disease???
No, we are not saying that.
Proving causality is the hardest task in science.
In addition, there have been a few studies in the past that have looked at viral infections as the cause of Parkinson’s disease that found strong associations with other viruses. For example this study:
Title: Infections as a risk factor for Parkinson’s disease: a case-control study.
Authors: Vlajinac H, Dzoljic E, Maksimovic J, Marinkovic J, Sipetic S, Kostic V.
Journal: Int J Neurosci. 2013 May;123(5):329-32.
In this study, the researchers found that Parkinson’s Disease was also significantly associated to mumps, scarlet fever, influenza, and whooping cough as well as herpes simplex 1 infections. They found no association between Parkinson’s disease and Tuberculosis, measles or chickenpox though.
This result raises the tantalizing possibility that other viruses may also be involved with the onset of Parkinson’s disease (it should be added though that this study was based on only 110 people with Parkinson’s (compared with 220 controls) in one particular geographical location (Belgrade, Serbia)).
So different viruses may cause Parkinson’s disease?
We are not saying that either, but we would like to see more research on this topic.
And the situation may actually be more complicated than we think.
Recently, it has been reported that previous infection with flaviviruses (such as dengue) actually enhances the effect of Zika virus infect (Click here to read more on this). That is to say, a prior infection by one particular virus may exacerbate the infection of another virus. It could be that a previous infection by one virus increases that chance that a later infection by another virus – a particular combination of viral infections – may result in Parkinsonian symptoms (we are simply speculating here).
Add to this complicated situation, the sheer number of unknown viruses. It is estimated that there are a minimum of 320,000 mammalian viruses still awaiting discovery (Click here for the source of this statistic), thus it is possible that additional unknown viruses may be involved with disease initiation for conditions like Parkinson’s disease.
A gang of unknown thieves in the night perhaps?
So what does it all mean?
Summing up: last week a new study was published that supported previous results that Hepatitis C viral infections could increase the risk of developing Parkinson’s disease. The results are important because they replicate previous findings from a different population of people.
The findings do not immediately mean that people with Hepatitis C are going to develop Parkinson’s disease, but it does suggest that they may be more vulnerable. The findings also suggest that more research is needed on the role of viral/infectious agents in the development of Parkinson’s disease.
We would certainly like to see more research in this area.
The banner for today’s post was sourced from Youtube
Here at the SoPD, we like our gadgets and new technology.
And we believe that there is enormous potential for people with Parkinson’s disease to benefit hugely even from some of the small technological advances that seem to be occurring on a day basis.
Today’s post will review a recent study that looked at tested the benefits of a smartphone application for people with Parkinson’s disease.
A schematic illustrating the limited monitoring of Parkinson’s. Source: Riggare
On her great blog, Swedish engineer and ‘proud mother’ Sara Riggare posted the image above to illustrate the ridiculous current situation regarding the standard monitoring of Parkinson’s disease.
As the schematic perfectly illustrates, in 2014 Sara spent 8,765 hours conducting ‘self care’. That is, she was applying her own knowledge and experience to managing her Parkinson’s disease. For just one hour in that year was her Parkinson’s actually being monitored by a medical clinician (8,766 being the number of hours in a year).
This is actually a very serious problem – for not only the Parkinson’s community – but anyone suffering from a long-term medical condition. How are they to gage their current situation on a day to day basis when they have such infrequent visits to their medical specialist?
And this is where technology can help.
But, before we begin:
FULL DISCLOSURE NO.1: the author of this blog is an author in the study that will be discussed (#ThisIsNotShamelessSelfPromotion).
FULL DISCLOSURE NO.2: We here at the SoPD are in no way benefitting from mentioning the study here. The company behind the product, umotif, has not asked us nor been contacted by us regarding this post (in fact, they are completely unaware that we are posting this). We are writing this post simply because we thought that it would be of interest to the wider Parkinson’s community. And yes, as other technology comes to along, we will bring it to you attention by posting about it here.
With all of that out of the way, the study is AMAZING!
Title: Using a smartphone based self-management platform to support medication adherence and clinical consultation in Parkinson’s disease: Results from the SMART-PD Randomised Controlled Trial v4.
Authors: Lakshminarayana R, Wang D, Burn D, Barker RA, Chaudhuri KR, Galtrey C, van Guzman N, Hellman B, Pal S, Stamford J, Steiger M, Stott SRW, Teo J, Barker RA, Wang E, Bloem BR, van der Eijk M, Rochester L, & Williams A
Journal: NPJ Parkinson’s disease (2017), 3, 2.
PMID: N/A (This article is OPEN ACCESS if you would like to read it)
The company behind the application approached various clinical research groups around the UK and proposed to run a study of their new product. The software had many features (including information about medication, a reminder alarm for when medication should be taken, tests/games, and links to other resources online).
A programmable reminder system for medication. Source: Nature
The primary focus of the software, however, was a flower-petal shaped motif that the participants could manipulate to indicate how they were feeling.
The umotif flower motif. Source: SalusDigital
Participants could drag each coloured petal in or out to indicate how they were feeling at a particular moment in time. The smaller the petal, the more lower the score. And each petal represented different aspects of daily life, for example the moon and stars (dark blue) petal allowed an indication of how one slept.
Each time the participant indicated their current status on the flower motif, the information was recorded and could be tracked over days, weeks, and months. This level of information allowed people to begin to see patterns in their own behaviour over time, with some people getting poorer sleep during the middle of the month for example. And different variables could be compared (such as sleep score with exercise score), providing users with a more dynamic idea of their situation over time.
Comparing scores between measures over time. Source: Nature
A total of 215 people with Parkinson’s disease were randomly assigned to either receive the application (106 subjects) or not (acting as a control subject; 109 subjects). Both groups were contacted by the investigators fours times during the 16 week trial and feedback was provided in addition to any changes in their treatment regimes.
72% of participants application group continued to use and engage with the application throughout the 16-week trial. By the end of the study, the application group demonstrated significantly improved adherence to their treatment regime when compared to the control group. Curiously, the application also significantly improved patients’ perception of quality of follow up consultations, demonstrating unexpected benefits.
And at the end of the study all of the control group participants in the study were allowed to begin using the application, while the application group continued to use it.
One interesting aspect of the study was the lack of interaction with technology by the target population. 180 people who were initially invited to take part in the study could not because they did not have smartphones (with iPhone/iPad or Android operating systems). So obviously there are opportunities for alternative approaches to this kind of tracking (other than a smartphone).
What does it all mean?
This smartphone application is a user friendly approach to tracking someone’s Parkinson’s over time, getting around the ‘lack of monitoring’ issue that concerns many in the community.
Umotif and Parkinson’s UK have kindly made this video about the study results so we might just sit back and let them explain what it all means and point out all of the benefits.
We are working on additional posts about wearable tech for Parkinson’s disease, which will be coming soon.
So stay tuned.
The banner for today’s post was sourced from ParkinsonsMovement