A new and highly interesting study published in The Lancet, from Tom Foltyne’s team in London, suggests that a safe and effective drug called exenatide, which is normally used to treat diabetes, may have the potential to slow the underlying disease process in Parkinson’s disease patients.

This is an exceptionally important landmark study that, for the first time, provides evidence in a controlled way that it may be possible to slow the underlying disease in Parkinson’s in people using a currently available drug. If this finding holds up to further investigations, this will have been a watershed for a disease that affects approximately 70,000 Australians from all walks of life. 

Parkinson’s disease affects people in different ways, but generally is classified as a “movement disorder.” It results because special nerve cells in the brain called dopamine neurons are lost from the brain. Symptoms may include muscle rigidity, tremor, postural instability and slowness of movement. The symptoms get progressively worse over time. Many people think tremor is the hallmark of Parkinson's, but in around 30 per cent of cases tremor is not present. 

Parkinson's doesn’t just affect movement. Non-motor symptoms such as pain, depression, anxiety, and problems with memory, sleep and bowel function can also occur and have an impact on the day-to-day life of the person with Parkinson’s. Despite decades of research efforts, there are no cures and the disease continues to worsen over time until the symptomatic treatments are less and less useful. No currently available treatments slow the underlying disease process in humans. There is a urgent need for treatments that slow the underlying disease.  

This study by Tom Foltyne provides hope of a new way forward. The study was designed to judge the safety of exenatide (an injectable treatment approved for use in type II diabetes) and to gain preliminary data on whether exenatide might slow down Parkinson’s disease progression in humans. 

The study showed that people with Parkinson’s disease who injected the drug exenatide for 48 weeks were indeed better off than patients who had injected a placebo, as far as their movement symptoms were concerned. 

This is an incredibly important study but still early stage result. 

If it holds up, this will be the first disease-modifying therapy for Parkinson’s disease. Remarkably, this therapy would not have been predicted from genetic studies. It suggests a link between brain insulin resistance and Parkinson’s disease.

It is now of utmost importance to perform further studies, both to confirm this finding and to more deeply understand the link between insulin resistance and Parkinson’s disease, and the potential for identifying more specific and effective treatments than the diabetes treatment. We and a number of others around the world are exceptionally interested in these research questions.

The study reported by Tom Foltyne’s team was a collaboration with the Cure Parkinson’s Trust, London, and Michael J Fox foundation among other important contributors.