NEW Research - Motor complications in Parkinson's disease: 13‐year follow‐up of the CamPaIGN cohort

Back on the blog for the first time in a long time...

This marks another NY resolution to speak and flag more about the research that I/we think is interesting or important in the early identification or prediction of PD. In addition, we like to mention good quality clinical and genetic studies that tell us more about PD in general (not just prediction and early identification). 

First off, the latest from the CAMPAIGN study. CAMPAIGN is one of the most rigorous and thorough long term studies of PD. The team have managed to follow up the people that they recruited with PD for a long, long time in order to help us learn more about the features that emerge over time.

In the present study, they show that eventually motor complications may be inevitable and that current drugs become less effective/predictable over time. Importantly they provide further support for the notion that levodopa replacement itself is not a cause of motor fluctuations and that thoughts about saving levodopa for the future (i.e. not starting after diagnosis) are probably outdated ideas.

Ultimately, whilst the available treatment options are good for most patients, the results here support our ongoing desire to find drugs that delay progression rather than just manage the symptoms...

The link to the study is here and it is open access (👌). The abstract is copied below.
https://onlinelibrary.wiley.com/doi/full/10.1002/mds.27882

Alastair Noyce

PLAIN ENGLISH: Gout and the risk of Parkinson's disease in older adults

First blog post of the year from me and, after feedback from literally everyone, I will be making a concerted effort to make them easy (easier) to understand. I can't get rid of the science I'm afraid... after all this is a research blog. But I (and we) can make bigger efforts to keep the focus on predicting Parkinson's, the PREDICT-PD study (predictpd.com) and related projects. 

The reason this blog was started was to help researchers, patients and the public understand how we use and weigh emerging research, which in turn informs our approach to our work on Parkinson's.

Take this study as an example... it looked at health insurance claims data from the USA over a 6 year period. The researchers looked at the link between claims for gout and subsequent claims for Parkinson's. They observed that, compared to people that made claims for other illnesses, people that claimed for gout were more likely to claim for Parkinson's in subsequent years. This in turn offers a weak suggestion that gout might be in some way linked with a higher risk of Parkinson's. However... we also know that this is only part of a much bigger story.

The biggest determinant of gout is the amount of a chemical in the blood known as uric acid. Generally speaking, people with higher levels of uric acid are more likely to have gout. It has also been noted on multiple occasions that people with Parkinson's tend to have lower levels of uric acid (both after diagnosis and in the years before)... which in turn has led to strategies to try and boost uric acid levels to treat Parkinson's (without introducing gout). 

So how does that make any sense at all?? High uric acid is associated with an increase in gout, gout is associated with an increase of Parkinson's, but Parkinson's is associated with low uric acid levels...?? We seem to be going in circles. 

But what if the explanation is simple... what if Parkinson's disease consumes uric acid and makes it look like low levels of uric acid are causing Parkinson's, when in fact it is the other way around? There have been similar examples in cancer where vitamin E was noted to be low in people that had prostate cancer, leading to the suggestion of supplementing vitamin E to reduce cancer. Instead the cancer rates appeared to increase... so it wasn't that low vitamin E was causing cancer... it was cancer consuming vitamin E and supplementing vitamin E only added more fuel to the fire.

If for some reason Parkinson's consumes uric acid, then gout may actually increase the risk of being diagnosed with Parkinson's and strategies to boost uric acid to treat or protect against Parkinson's may not lead to benefit and have the opposite effect...

Of course, this is speculation and certainly not the final say on the matter. Further research will likely reveal the truth over time...

- Alastair Noyce


BMC Neurol. 2019 Jan 5;19(1):4. doi: 10.1186/s12883-018-1234-x.
Singh JA, Cleveland JD.

BACKGROUND: In the presence of limited available data, our objective was to assess the association of gout with the risk of incident Parkinson's disease (PD) in adults 65 years or older.

METHODS: We used the 5% random sample of Medicare claims data from 2006 to 2012 to examine the association of gout with incident PD. The multivariable Cox regression model adjusted for demographics, comorbidity, and common cardiovascular disease and gout medications. We calculated hazard ratios (HR) and 95% confidence interval (CI). Sensitivity analyses adjusted for comorbidity categorically, or individually and for additional cardiovascular comorbidities.

RESULTS: In a cohort study, 1.72 million Medicare beneficiaries were eligible. The mean age was 75 years (standard deviation [SD], 7.6), 58% were female, 86% were White and 37% had Charlson-Romano comorbidity index score of ≥2. We found that 22,636 people developed incident PD, 1129 with gout and 21,507 without gout. The respective crude incidence rates of incident PD were 3.7 vs. 2.2 per 1000 person-years. We found that gout was associated with 1.14-times higher hazard ratio (95% CI, 1.07, 1.21) of PD in the main analysis; findings were confirmed in sensitivity analyses. We noted that the risk differed slightly by age; ages 65-75, 75-85 and > 85 had hazard ratios of incident PD with gout of 1.27 (95% CI, 1.16, 1.39), 1.07 (95% CI, 0.97, 1.16) and 0.97 (95% CI, 0.79, 1.20), respectively, but no gender or race differences were noted.

CONCLUSIONS: Gout was associated with a higher risk of incident PD in older adults, with the risk being significant in the age group 65-75 years. Future studies need to assess the mechanisms of this increased risk.

Cognitive decline in Parkinson's disease: the impact of the motor phenotype on cognition

This is a nice large study looking at the relationship between different motor features of Parkinson's and having more severe cognitive features.

We already know that patients with a mainly shaky (tremulous) form of Parkinson's tend a run a milder course compared to those patients that have a very slow & stiff (akinetic rigid) form of Parkinson's. For example, patients with the tremulous form of Parkinson's also seem to live for longer than those with the akinetic rigid form. Of course these categories overlap substantially but they are generally well recognised.

Here the researchers show that in patients who tended to be more slow and stiff, scores on a variety of cognitive tests were worse than in the patients that had predominant tremor.

The study design was cross-sectional, which means that movement and cognition were measured at the same time. This means that strict conclusions cannot be drawn about the progression of movement or cognitive abnormalities either separately or together. The explanation for the association between akinetic-rigidity and worse cognition is likely due to involvement of common structures brain (more so than the structures that are involved in tremor), the overall burden of disease (likely to be less in those with predominant tremor), and shared risk factors (including genetic determinants).

- Alastair Noyce

J Neurol Neurosurg Psychiatry. 2018 Oct 8. pii: jnnp-2018-319008. doi: 10.1136/jnnp-2018-319008.

Wojtala J, Heber IA, Neuser P, Heller J, Kalbe E, Rehberg SP, Storch A, Linse K, Schneider C, Gräber S, Berg D, Dams J, Balzer-Geldsetzer M, Hilker-Roggendorf R, Oberschmidt C, Baudrexel S, Witt K, Schmidt N, Deuschl G, Mollenhauer B, Trenkwalder C, Liepelt-Scarfone I, Spottke A, Roeske S, Wüllner U, Wittchen HU, Riedel O, Dodel R, Schulz JB, Reetz K.

https://jnnp.bmj.com/content/early/2018/10/07/jnnp-2018-319008.long

OBJECTIVES: Parkinson's disease (PD) is the second most common neurodegenerative disorder and is further associated with progressive cognitive decline. In respect to motor phenotype, there is some evidence that akinetic-rigid PD is associated with a faster rate of cognitive decline in general and a greater risk of developing dementia.The objective of this study was to examine cognitive profiles among patients with PD by motor phenotypes and its relation to cognitive function.

METHODS: Demographic, clinical and neuropsychological cross-sectional baseline data of the DEMPARK/LANDSCAPE study, a multicentre longitudinal cohort study of 538 patients with PD were analysed, stratified by motor phenotype and cognitive syndrome. Analyses were performed for all patients and for each diagnostic group separately, controlling for age, gender, education and disease duration.

RESULTS: Compared with the tremor-dominant phenotype, akinetic-rigid patients performed worse in executive functions such as working memory (Wechsler Memory Scale-Revised backward; p=0.012), formal-lexical word fluency (p=0.043), card sorting (p=0.006), attention (Trail Making Test version A; p=0.024) and visuospatial abilities (Leistungsprüfungssystem test 9; p=0.006). Akinetic-rigid neuropsychological test scores for the executive and attentive domain correlated negatively with non-tremor motor scores. Covariate-adjusted binary logistic regression analyses showed significant odds for PD-mild cognitive impairment for not-determined as compared with tremor-dominant (OR=3.198) and akinetic-rigid PD (OR=2.059). The odds for PD-dementia were significant for akinetic-rigid as compared with tremor-dominant phenotype (OR=8.314).

CONCLUSION: The three motor phenotypes of PD differ in cognitive performance, showing that cognitive deficits seem to be less severe in tremor-dominant PD. While these data are cross-sectional, longitudinal data are needed to shed more light on these differential findings.

News from the Land of Milk and Honey

I had the good fortune to attend a conference on Precision Medicine and Ageing today. This brought some of the leading scientists from the UK and Israel together, as part of the British Council’s Britain Israel Science and Innovation Network. The day included speakers talking about the latest breakthroughs in genomics, neuroscience, cellular biology and many other fields of scientific endeavour and how they relate to the biology of ageing (in health as well as disease) and how these breakthroughs are bringing us closer to the ‘promised land’ of Personalised, or Precision medicine.

The talk that I found the most interesting came from Dr Maya Leventer-Roberts, from the Clalit Research Institute. This is not a university department, but the in-house research arm of the largest of Israels four health providers. They have an unparallelled treasure-trove of health data. She explained that all Israeli citizens belong to one of these four organisations who provide all aspects of care: GP, pharmacy, testing laboratories, hospitals – you name it. What’s more, very few people change providers, so they have a well-coded database of people’s wellness, illness and health behaviour at all stages of life.

I have since found a paper from last year which uses some of their data to examine a relatively neglected aspect of Parkinson’s – depression. Unfortunatley a huge proportion of people with Parkinson’s struggle with depression. We also know that late onset depression is a risk factor for Parkinson’s. 

In this study, they looked at mortality rates in Parkinson’s and the association with how adherent people were with antidepressents. They analysed the data of 10,000 people with a diagnosis of Parkinson’s as well as at least one prescription of an antidepressant. They then categorised people into how frequently they tookthe antidepressants by comparing their prescriptions from the doctor with the number of purchases of antidepressants from the pharmacies. Finally they looked at death by any cause over the 4 year study period.

They found that the people who had Parkinson’s and depression who took their antidepressants the least were 43% more likely to die within the 4 year period, compared to those who took it the most regularly. The increased mortality was exacerbated by having an increasing number of other medical problems.

I must stress the old adage: association does not equal causation. This kind of retrospective observational study cannot provethat one thing causes another. However, it is an important reminder that depression is an important aspect of Parkinson’s, and that poorly managed depression is associated with increased mortality. It also reminds me that older people, with Parkinson’s, depression and perhaps four or five other medical conditions may be on 15-20 or more tablets a day. What can I do as a clinician to help them remember what each is for, and why each is important to take? What can we do as a society to help people with depression with both drug and non-drug treatment options? How can we better prepare ourselves, individually and societally, for ageing and the only true inevitability of life?

RNR

Shoval G, Stubbs B, Balicer RD, Feldman B, Hoshen M, Zalsman G, et al. 

Low adherence to antidepressants is associated with increased mortality in Parkinson disease patients. 

Parkinsonism Relat Disord. 2017 Oct;43:92–6.

INTRODUCTION:The purpose of this study was to evaluate the relationship between adherence to antidepressants (AD) and all-cause mortality in a population-based cohort of patients with Parkinson's Disease (PD).

METHODS:From a database of more than 4 million people, 8553 patients with PD who purchased an AD at least once between the years 2008-2011 were retrospectively followed for all-cause mortality over 4-years. Adherence was measured as a ratio between dispensed and prescribed durations and was modeled as: non-adherence (<20%, n = 1566), poor (20%-50%, n = 1184), moderate (50%-80%, n = 1584), and good (>80%, n = 4219) adherence. Multivariable survival analyses adjusted for demographic and clinical variables including physical comorbidities known to influence mortality were conducted, however there was no adjustment for other psychiatric disorders and medications.

RESULTS:Unadjusted mortality rates were 20.4%, 25.1%, 23.4% and 25.6% in those classified as non-adherent, poor, moderate and good adherence respectively (χ2 = 18.45, p < 0.0001). The non-adherent and poor adherence groups had significantly increased adjusted mortality hazard ratios (HR) of 1.43 (CI: 1.26-1.62) and 1.26 (CI: 1.1-1.44) respectively compared to the good adherence group. Using the same model, the adjusted HR for death among males was 1.49 [95% CI: 1.36-1.62] compared to females. People with PD and Charslon's Comorbidity Index score of 3-4 (HR 1.3, P < 0.001) and 5+ (HR 1.78, P < 0.001) were more likely to die than those with 0-2 comorbidities.

CONCLUSIONS:Our findings suggest that poor adherence to AD is associated with increased all-cause mortality in people with PD. Given the high prevalence of depression and AD effectiveness, efforts to promote adherence should be prioritized in clinical practice.

Plain English - Type 2 diabetes linked to higher rate of Parkinson’s

Some of you may have already seen in the newspapers details of our recent study on the link between Type 2 Diabetes and Parkinson's disease... 

In our study, we used the Hospital Episode Statistics database and looked at a very large number of people (2,017,115) with a type 2 diabetes diagnosis during a hospital admission from 1999-2011, excluding people who already had a Parkinson’s diagnosis. We compared them to a group of over 6 million people from the same database without type 2 diabetes. Among the people with diabetes, 14,252 had a diagnosis of Parkinson’s during a later hospital admission, compared with 20,878 in the comparison group. After excluding people with some similar conditions, and controlling for age, sex and region of residence, we found that people with type 2 diabetes were 32 per cent more likely to have a subsequent diagnosis of Parkinson’s. The link was strongest among younger people (aged 25-44), and people with more complications from their diabetes.

Over the years, this link has proved less of a challenge to study and more of a challenge to interpret. For example, whilst most studies done on this subject suggest some sort of link between diabetes and risk of Parkinson's, the curious fact is that some suggest an increased risk of Parkinson's in those with diabetes, and some studies suggest a decreased risk. The difference may be accounted for by the design of the individual studies and requires further exploration. Our study adds to the literature and increases confidence that the association is such that type 2 diabetes increases risk, but whether this is due to common underlying mechanisms of disease or a true causal link between the two remains to be seen.

What is true, is that diabetes drugs may help treat Parkinson's, and we have already seen a great example of this in the last year. Exenetide appears to have a benefit on the symptoms of Parkinson's and furthermore may alter the underlying disease process. But before we can say that definitively, we need further studies.

- Alastair Noyce

Neurology
Eduardo De Pablo-Fernandez, Raph Goldacre, Julia Pakpoor, Alastair J. Noyce, Thomas T. Warner First published June 13, 2018, DOI: https://doi.org/10.1212/WNL.0000000000005771

http://n.neurology.org/content/early/2018/06/13/WNL.0000000000005771

Objective
To investigate the association between type 2 diabetes mellitus (T2DM) and subsequent Parkinson disease (PD). 

Methods
Linked English national Hospital Episode Statistics and mortality data (1999–2011) were used to conduct a retrospective cohort study. A cohort of individuals admitted for hospital care with a coded diagnosis of T2DM was constructed, and compared to a reference cohort. Subsequent PD risk was estimated using Cox regression models. Individuals with a coded diagnosis of cerebrovascular disease, vascular parkinsonism, drug-induced parkinsonism, and normal pressure hydrocephalus were excluded from the analysis.

Results
A total of 2,017,115 individuals entered the T2DM cohort and 6,173,208 entered the reference cohort. There were significantly elevated rates of PD following T2DM (hazard ratio [HR] 1.32, 95% confidence interval [CI] 1.29–1.35; p < 0.001). The relative increase was greater in those with complicated T2DM (HR 1.49, 95% CI 1.42–1.56) and when comparing younger individuals (HR 3.81, 95% CI 2.84–5.11 in age group 25–44 years).

Conclusions
We report an increased rate of subsequent PD following T2DM in this large cohort study. These findings may reflect shared genetic predisposition and/or disrupted shared pathogenic pathways with potential clinical and therapeutic implications.

Plain English - Low body mass index and life prognosis in Parkinson's disease

Over the last few years we have seen research that suggests being underweight has a negative or detrimental effect on survival with diseases like Parkinson's. The same has been shown for motor neurone disease and Alzheimer's. Whether this reflects a more aggressive form of the disease, which in itself also affects weight, or whether being a bit heavier makes you a bit more 'robust' to these diseases remains to be seen. 

In this study the authors show something similar. When they looked backwards in time in a large number of patients with Parkinson's, they saw that those that were underweight had survived for a shorter time than those that were normal weight or over weight. We must be cautious in how we interpret the results because they don't necessarily suggest that being heavier is better and indeed obesity causes an increase in heart and vascular disease, diabetes, and cancer. However it does suggest that being underweight and having Parkinson's is not a good idea either. Aiming for a recommended normal weight and BMI (body mass index) appears to offer the best option considering all outcomes. 

The reason I am particularly interested in this study is because last year we published research showing that higher BMI appears to protect you against Parkinson's. The special thing about the analysis that we did was that it assessed the effect that BMI has on Parkinson's (BMI -> Parkinson's) without being affected by the effect that Parkinson's has on BMI (Parkinson's -> BMI). The method we used was called Mendelian randomisation and it is increasingly used to assess whether risk factors cause a disease as opposed to simply being associated.

The relationship between weight and BMI and Parkinson's disease is complicated and is an important area for further study.

- Alastair Noyce

Parkinsonism Relat Disord. 2018 May 15. pii: S1353-8020(18)30241-4. doi: 10.1016/j.parkreldis.2018.05.011. [Epub ahead of print]
Park K, Oeda T, Kohsaka M, Tomita S, Umemura A, Sawada H.

https://www.prd-journal.com/article/S1353-8020(18)30241-4/fulltext

INTRODUCTION: Patients with Parkinson's disease (PD) frequently lose weight, even in the early stages of the disease. Our objective was to clarify the association between low body mass index (BMI) and life prognosis in PD.

METHODS: We conducted a retrospective cohort study of 651 PD patients (380 females), with a primary endpoint of survival. Because of sex differences in BMI, male and female data were separated. We compared survival times between underweight (BMI < 18.5) and non-underweight (BMI ≥ 18.5) patients and calculated hazard ratios (HRs) adjusted for other relevant factors. To investigate the semi-quantitative relationship between relative risk of death and BMI, we divided patients into lower, middle, and upper thirds of BMI and calculated the HRs of the lower and upper thirds, with reference to the middle third.

RESULTS: Seventy-nine patients (41 females) died over a mean (standard deviation) observation period of 39 (26) months. Underweight patients had poorer life prognosis than non-underweight patients and the difference was larger in males than in females (adjusted HR 3.8 (95% confidence interval 1.9-7.9) in males and 1.8 (0.9-3.5) in females). In males, the relationship between survival and BMI was much poorer in the bottom third and slightly poorer in the top third compared with the middle third. In females, the higher the BMI, the better the survival prognosis; however, the difference was not statistically significant.

CONCLUSION: Low BMI had a significant impact on the life prognosis of PD patients, especially males.

Anti–Tumor Necrosis Factor Therapy and Incidence of Parkinson Disease Among Patients With Inflammatory Bowel Disease

This is a really interesting study. It looks at the relationship between inflammatory bowel disease and Parkinson's disease, which is something I have been wanting to do for sometime. There is lots of seemingly circumstantial evidence linking IBD and PD, including gastrointestinal inflammation, unusual relationships with smoking (for ulcerative colitis) and an association with the LRRK2 gene (for Crohn's disease). Here the authors show an association between PD and all IBD, and between PD and Crohn's disease and ulcerative colitis separately. People with IBD appeared to be at increased risk of PD during follow-up...

Perhaps more intriguing is that fact that they show a reduction in that increased risk if people were treated with drugs targeted against the mechanisms of IBD. Whether this represents a reduction in risk because the IBD is better treated or because the same drugs target a pathway that is important to PD remains to be seen....

Inga Peter, PhD; Marla Dubinsky, MD; Susan Bressman, MD; Andrew Park, PhD, MPH; Changyue Lu, MS; Naijun Chen, MS; Anthony Wang, PhD, MPH

JAMA Neurology 23rd April 2018

https://jamanetwork.com/journals/jamaneurology/fullarticle/2679038

Importance
Despite established genetic and pathophysiologic links between inflammatory bowel disease (IBD) and Parkinson disease (PD), clinical data supporting this association remain scarce. Although systemic inflammation is considered a potential biological mechanism shared between the 2 diseases, the role of reduced systemic inflammation through IBD-directed anti–tumor necrosis factor (anti-TNF) therapy in PD risk is largely unknown.

Objective
To compare the incidence of PD among individuals with or without IBD and to assess whether PD risk among patients with IBD is altered by anti-TNF therapy.

Design, Setting, and Participants 
This is a retrospective cohort study analyzing information in the Truven Health MarketScan administrative claims database and the Medicare Supplemental Database between January 1, 2000, and March 31, 2016. Individuals were selected who had at least 2 claims for IBD diagnoses, at least 6 months of follow-up, and no prior diagnosis of PD on or before the IBD index date. Exposure to Anti-TNF therapy was measured from the anti-TNF index date to the last date of anti-TNF coverage or the end of enrollment or PD index date, whichever was earliest. Incidence rates per 1000 person-years were calculated, and crude and adjusted incidence rate ratios were estimated by Poisson regression models and presented with 95% CIs.

Main Outcomes and Measures 
Incidence of PD among patients with IBD with or without exposure to anti-TNF therapy.

Results
In total, 144 018 individuals with IBD were matched on age, sex, and year of index date with 720 090 unaffected controls. Of them, 1796 individuals had at least 2 PD diagnoses and at least 1 filled PD-related prescription. The mean (SD) age of individuals with IBD was 51 (17) years, and 44% were men. The incidence of PD among patients with IBD was 28% higher than that among unaffected matched controls (adjusted incidence rate ratio, 1.28; 95% CI, 1.14-1.44; P < .001). A 78% reduction in the incidence rate of PD was detected among patients with IBD who were exposed to anti-TNF therapy compared with those who were not exposed (adjusted incidence rate ratio, 0.22; 95% CI, 0.05-0.88; P = .03).

Conclusions and Relevance 
A higher incidence of PD was observed among patients with IBD than among individuals without IBD. Early exposure to antiinflammatory anti-TNF therapy was associated with substantially reduced PD incidence. These findings support a role of systemic inflammation in the pathogenesis of both diseases. Further studies are required to determine whether anti-TNF treatment administered to high-risk individuals may mitigate PD risk.