A DRUG used to treat diabetes could slow the debilitating progression of Parkinson's disease, scientists say.
Parkinson's is a devastating nervous system disorder affecting 10 million people worldwide, with no current cure.
Symptoms include rhythmic shaking known as tremors, slowed movement, impaired speech and problems balancing, which get worse over time.
Researchers have been exploring a class of drugs called glucagon-like peptide-1 receptor agonists (GLP-1 RA) for their potential to protect brain neurons.
GLP-1 RAs are now commonly used to treat diabetes and obesity. A widely-known example of a GLP-1 drug is Ozempic, while Wegovy is for weight loss.
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In a new study published in the New England Journal of Medicine, 156 patients with early-stage Parkinson's were recruited across France.
Researchers chose to test the drug lixisenatide. Made by Sanofi and sold under the brand names Adlyxin and Lyxumia, the type 2 diabetes drug has since been discontinued in the UK.
Patients were randomly chosen to receive daily injections of lixisenatide or a placebo.
This is the first time that we have clear results, which demonstrate that we had an impact on the progression of the symptoms of the disease
Olivier Rascol
After one year of follow up, the group on taking the diabetes drug saw no worsening of their movement symptoms, while those on the placebo did.
The effect was "modest" according to the paper, and was noticeable only when assessed by professionals "who made them do tasks [such as ]walking, standing up, moving their hands", senior author Olivier Rascol, a neurologist at Toulouse University, said.
But, he added, this may just be because Parkinson's disease worsens slowly, and with another year of follow up, the differences might become much starker.
So far, evidence of the clinical benefits of GLP-1 drugs in patients with Parkinson's has been limited and early studies have proved inconclusive.
"This is the first time that we have clear results, which demonstrate that we had an impact on the progression of the symptoms of the disease and that we explain it by a neuroprotective effect," Dr Rascol said.
Gastrointestinal side effects were common on the drug and included nausea, vomiting and reflux, while a handful of patients experienced weight loss.
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Dr Rasol and co-author Wassilios Meissner, a neurologist at Bordeaux University Hospital, both stressed more study would be required to confirm safety and efficacy before the treatment can be given to patients.
Promising findings that need replication
Michael Okun, medical director of the Parkinson's Foundation, said that from a practical standpoint, the differences in patient outcomes were not clinically significant, but "statistically and compared to other studies, this type of difference should draw our interest and attention".
"Experts will likely argue whether this study meets a minimum threshold for neuroprotection, and it likely does not," Dr Okun said, adding the weight loss side effect was concerning for Parkinson's patients.
Rodolfo Savica, a professor of neurology at the Mayo Clinic in Minnesota added: "The data so far are suggestive of a possible effect - but we need to replicate the study for sure."
According to Parkinson's UK, diabetes drugs like lixisenatide are being scrutinised by scientists for treating Parkinson's because GLP-1 receptors are also found in the brain.
Lab-based experiments have suggested that activating them can boost the function of dopamine connections, have anti-inflammatory properties, improve energy production, and switch on cell survival signals.
Lixisenatide is the second diabetes drug to go through clinical trials for Parkinson’s, the first being exenatide.
Professor David Dexter, director of research at Parkinson’s UK, said of the new study: "The most significant part of these results are the lack of deterioration seen in the clinical measurement of motor symptoms in those receiving lixisenatide over the 12 months.
"This is promising, but from this study it's hard to say whether the drug is slowing the progression of the condition. A longer trial could be able to show this and could be a logical next step.
“It will be interesting to see the results from a similar drug called exenatide.
"Previous clinical trial results suggest it could be more beneficial than lixisenatide."
Research shows that GLP-1 drugs could be harnessed to improve health in other ways, as they appear to have potential to treat Alzheimer's, as well as heart disease, fatty liver disease, and chronic kidney disease.
It's been suggested that patients with sleep apnoea, heart failure and alcohol addiction could also benefit.
