Despite what we envision when we think about Parkinson’s disease, early symptoms for the disease can be hard to identify. But like most conditions, identifying Parkinson’s early is imperative to treating the complications that come from it, which includes an increased risk for both depression and even cancers. Now, a study led by researchers from Massachusetts General Hospital (MGH) has found that early Parkinson’s patients who experience weight loss are at risk for rapid progression of the disease.

"I suspect we may be looking at several subtypes of this disease," said Dr. Anne-Marie Wills, from the MGH Department of Neurology and Neurological Clinical Research Institute, in a statement. "The patients who experience early weight loss appear to have a more severe, systemic form of the disease, possibly due to involvement of the neuroendocrine system or the gastrointestinal nervous system, while those who gained weight may have a milder form of the disease."

Wills and her colleagues used data from an NIH-sponsored clinical trial that took place between 2007 and 2013 and investigated the use of creatine to treat early-stage Parkinson’s. Three to five year's worth of data on 1,673 study participants was collected, including annual height, weight measurements, and results from the Unified Parkinson's Disease Rating Scale (UPDRS). All patients were within five years of their diagnosis and 90 days to two years after beginning treatment with dopamine-releasing drugs, which stopped after creatine served little to no benefit.

Although body mass index (BMI) remained stable among 77 percent of patients after five years, 158 patients experienced weight loss and 223 ended up gaining weight. Participants who ended up losing weight by the end of the study also had a greater average increase in their UPDRS score, which directly indicated worsening Parkinson’s symptoms. This included both motor symptoms and non-motor compared to patients whose weight stayed the same. Patients who ended up gaining weight experienced the smallest annual increase in their UPDRS score.

"Since this is just the first observation of this association in Parkinson's, we cannot recommend any changes to standard clinical care right now," Wills added. "But in my own practice, I try to prevent weight loss in patients, and I would recommend providers to be attentive to weight changes in their patients, even early in the disease."

While this does seem to be the first study suggesting a link between weight gain and Parkinson’s disease progression, there is a lot of evidence showing how diet can actually impact symptoms and progression of the disease. For example, a 2013 study conducted at Tel Aviv University found that the artificial sweetener, mannitol, has the potential to prevent α-synuclein molecules from sticking together, which inhibits neurons’ ability to send messages in a forward direction. Meanwhile, a string of studies came up with conflicting results regarding whether cholesterol-lowering statins actually increase or decrease our risk for Parkinson’s.

Source: Su X, Wang J, Wills A, et al. Association Between Change in Body Mass Index, Unified Parkinson’s Disease Rating Scale Scores, and Survival Among Persons With Parkinson DiseaseSecondary Analysis of Longitudinal Data From NINDS Exploratory Trials in Parkinson Disease Long-term Study 1. JAMA Neurology. 2016.