Tuesday, 7 November 2017

Let them eat cake!

There has been some interesting work on weight and its link to Parkinsons coming out in the last few years including Alastair's paper, which suggested a protective effect of higher BMI for future development of Parkinsons disease. However, there have also been observational studies linking increased BMI in mid-life to future risk of Parkinson's disease.

This paper, from a group in Aberdeen, looks at a cohort of patients from initial diagnosis of Parkinsons disease or atypical parkinsonism with yearly follow up and includes an age and sex-matched control group who didn't develop the disease. It is illuminating from two points of view - firstly for the weight differences between people just diagnosed with Parkinson's and their healthy contemporaries and secondly for the impact of weight loss in Parkinsons and atypical Parkinsonism.

Even very early in the disease, at diagnosis, people with Parkinsons are likely to weigh significantly less than healthy controls, with an average weight of 72.5kg vs 77.3kg.  Weight loss after diagnosis is also important - it was associated with dementia, higher dependency and mortality. The only significant predictor of weight loss was older age.

These findings raise a lot of questions - given that lower weight is present at diagnosis and therefore presumably prior to diagnosis - is weight loss or low weight a risk factor for Parkinsons or is it part of the prodromal stage of the disease? If it is part of the prodrome, is it due to reduced appetite, increased energy demands or secondary to other prodromal features - is eating less pleasureable due to smell loss?

For patients already diagnosed with Parkinsons, monitoring weight and addressing factors that may affect appetite and eating are important, especially because of the prognostic implications. But while this paper identifies the link, it's not able to address causality directly - so the question of whether weight acts as a marker of disease risk and more severe disease once diagnosed or contributes directly to worse outcomes remains unanswered. Sadly it's still unclear if targeted intervention as suggested in the article i.e.eating more cake, has any effect on outcomes.

-Anna

 https://www.ncbi.nlm.nih.gov/pubmed/29079685

Neurology. 2017 Oct 27. pii: 10.1212/WNL.0000000000004691 doi:10.1212/WNL.0000000000004691. [Epub ahead of print]

Early weight loss in parkinsonism predicts poor outcomes: Evidence from an incident cohort study.

Cumming K, Macleod AD, Myint PK, Counsell CE

Abstract
OBJECTIVE:
To compare weight change over time in patients with Parkinson disease (PD), those with atypical parkinsonism, and matched controls; to identify baseline factors that influence weight loss in parkinsonism; and to examine whether it predicts poor outcome.
METHODS:
We analyzed data from the Parkinsonism Incidence in North-East Scotland (PINE) study, an incident, population-based prospective cohort of parkinsonian patients and age- and sex-matched controls with annual follow-up. Mixed-model analysis described weight change in patients with PD, those with atypical parkinsonism, and controls. Baseline determinants of sustained clinically significant weight loss (>5% loss from baseline) and associations between early sustained weight loss and death, dementia, and dependency in parkinsonism were studied with Cox regression.
RESULTS:
A total of 515 participants (240 controls, 187 with PD, 88 with atypical parkinsonism) were followed up for a median of 5 years. At diagnosis, atypical parkinsonian patients had lower body weights than patients with PD, who were lighter than controls. Patients with PD lost weight more rapidly than controls, and weight loss was most rapid in atypical parkinsonism. After multivariable adjustment for potential confounders, only age was independently associated with sustained clinically significant weight loss (hazard ratio [HR] for 10-year age increase 1.83, 95% confidence interval [CI] 1.44-2.32). Weight loss occurring within 1 year of diagnosis was independently associated with increased risk of dependency (HR 2.11, 95% CI 1.00-4.42), dementia (HR 3.23, 95% CI 1.40-7.44), and death (HR 2.23, 95% CI 1.46-3.41).
CONCLUSION:
Weight loss occurs in early parkinsonism and is greater in atypical parkinsonism than in PD. Early weight loss in parkinsonism has prognostic significance, and targeted dietary interventions to prevent it may improve long-term outcomes.





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