Parkinson’s and the Common Cough

Parkinson’s is a neurodegenerative disease which damages the sufferer’s brain progressively over a number of years. With up to an estimated 10 million people with the condition worldwide, could new trials using a drug found in cough medicine hold hope for patients with this cruel condition?

As stated above, Parkinson’s is a neurodegenerative disease, meaning it damages the sufferer’s brain over time. It is caused by a loss of nerve cells in the substantia nigra (part of the brain), which leads to a reduction in dopamine in the brain. Dopamine is vital to the regulation of the movement of the body; a reduction in dopamine is responsible for many of the symptoms of Parkinson’s disease. The three main symptoms include involuntary shaking (i.e. a tremor), slow movement, and stiff or inflexible muscles. Exactly what causes the loss of nerve cells is unclear but most experts think it is a combination of genetic and environmental factors. Parkinson’s is the second most common aged-related, neurodegenerative disease after Alzheimer’s, with your risk of suffering increasing from 41 in 100,000 in your 40’s, to 1,900 in 100,000 by your 80’s, and men are 1.5 times more likely to develop it that women. Current treatments try to enhance the quality of life for the sufferer through physio- and occupational therapies, medication, and occasionally brain surgery.parkinsonsbrain

Parkinson’s doesn’t directly cause the death of sufferers, but places a huge strain on the bodies of patients, making some (such as the elderly) more susceptible to life-threatening infections. For many, symptoms can be mild and manageable for years, leading fulfilled lives. However, this is not always the case, and people deteriorate. So what research is underway, and what does cough medicine have to do with it?

There are many groups researching treatments and possible cures for Parkinson’s, such as The Cure Parkinson’s Trust, PD Frontline, hundreds of university and pharmaceutical groups, and Parkinson’s UK to name but a few. The Cure Parkinson’s Trust is one of the institutions which funds research into the drug traditionally found in cough medicine: Ambroxol. Ambroxol has been an active ingredient in cough medicines since the 1970s, but in recent years has been investigated for its potential to halt the progression of Parkinson’s. To date, there are no treatments which slow, stop or reverse the disease, making this drug potentially life-changing. The studies, led by University College London (UCL), concluded Phase II clinical trials on 17 human patients with Parkinson’s, finding ambroxol safe and well-tolerated by the participants, who took daily doses for 6 months. The next step is a trial with a much larger number of patients with Parkinson’s, studying not only the effects of the drug but also the patients’ genes which may contribute to the disease and its progression.ambroxol

So what is ambroxol doing? When used in cough medicine, ambroxol works to break up phlegm, promoting mucus clearance and easing a cough. For use in Parkinson’s, it is thought that ambroxol may help to reduce the unwanted build-up of a toxic protein in neurons, alpha-synuclein. Some people with Parkinson’s disease have a GBA gene mutation, which means they are more likely to develop movement impairment at a younger age and have a more rapid disease progression. This gene mutation can eventually lead to the build-up of toxic alpha-synuclein. Ambroxol has been shown to improve the function of an enzyme in the pathway, helping to reduce the build-up of alpha-synuclein, which researchers hope will slow the progression of Parkinson’s, improving stability and motor ability in people with Parkinson’s.  Below is a video of Dr Stephen Mullin from Plymouth University, explaining this line of Parkinson’s research.

Current Parkinson’s treatments do not target this pathway, and it is hoped that Ambroxol may be a candidate for long term use, potentially reducing or even halting progression of the disease. The small trial has highlighted the potential of Ambroxol, indicating better motor control and of quality of life for patients, but further testing is required. Researchers now need to determine safe dosage levels and the ability of Ambroxol to cross into the brain to take action. There is a lot of exciting research underway for neurodegenerative disorders, and Ambroxol could be the next big breakthrough.

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