Are we on the brink of a Parkinson’s breakthrough?
As cases soar, some specialists believe the key to a cure is within our grasp, finds Rosie Taylor
As you read this, we may have a cure for Parkinson’s disease, and just not know it. Several treatments on clinical trial could yet turn out to be a saving grace for the millions with the disease, as well as the population at large. For, according to new research, the degenerative neurological disease is affecting more people than ever before.
Last week, The Lancet revealed that the number of people worldwide with Parkinson’s had reached 6.1 million in 2016, almost two and a half times the 1990 figure of 2.5 million.
In the UK, Parkinson’s affects around one in 350 people, but by 2025, the number of Britons living with the disease will have increased by around 18 per cent to more than 168,000, according to separate figures from the charity Parkinson’s UK. This figure is set to almost double within 50 years, as the population ages and improvements in treatment mean more people survive other diseases such as cancer and heart disease.
In the face of a growing threat from the disease – symptoms of which include tremors, muscle stiffness, problems with balance, as well as depression – scientists have been working flat out to find new treatments. At present, medications merely reduce the severity of symptoms. But, finally, some think they are just five years away from unlocking the key to a cure.
Britain’s leading specialists believe a breakthrough is finally on the horizon, with several clinical trials exploring potential treatments launching this year and in 2019.
Dr David Dexter, deputy director of research at Parkinson’s UK, says: “It’s a positive time for research because we can see so much of the jigsaw coming together.”
When it comes to investment in research, Parkinson’s has long been overshadowed by a focus on other serious conditions, such as dementia and cancer. British Parkinson’s research charities received around £40 million in donations last year – less than half of the amount given to the country’s main Alzheimer’s charities, and a tenth of that received by Cancer Research UK.
But renewed interest in finding a cure and campaigning from charities and celebrities such as the actor Michael J Fox, who was just 29 when he was diagnosed with early onset Parkinson’s in 1991, means there are finally a host of human trials of new treatments under way or about to start.
Scientists are optimistic that at least one treatment being tested could hold the key to understanding what triggers the disease – or prove to be a cure.
Parkinson’s is a progressive neurodegenerative disorder where cells in the brain die off over time, leading to a loss of the chemical dopamine, which is vital for controlling movement. The main symptoms – shaking or tremors of body parts when at rest, slow movement and stiff or inflexible limbs – are often paired with depression, anxiety, sleep problems and loss of memory or cognitive function. Patients are normally diagnosed when they are over the age of 50. Their health deteriorates over time and they can ultimately become severely disabled. While the condition does not directly cause death, it makes the body vulnerable to complications, such as problems swallowing, or infections.
As there is currently no cure, existing treatments are designed to help minimise symptoms. The drugs can have unpleasant side effects – including triggering hallucinations or involuntary movements – and lose effectiveness over time.
But Dr Dexter says the research world is positive about the potential of the new therapies. “Thirty years ago, we knew which cells died in Parkinson’s, but we had no idea why. Now we’ve got to the point where we know so much more about the mechanisms, how they work and how they interact with each other. The exciting thing is that now we’re actually developing the drugs to stop these mechanisms. Within the next five or so years, we should know which ones are the key drivers in the disease.
“Any one of those clinical trials testing one of those avenues now may prove positive,” he says. “But if they don’t, it will still add to our understanding.”
Dr Simon Stott, deputy director of research at the Cure Parkinson’s Trust, explains that in order to find a cure for the disease, scientists must discover how to stop its progression, rejuvenate any remaining brain cells and replace those which have died.
He says: “The bad news is that we don’t have any one single treatment on the horizon that will do all three things. But the good news – and the most exciting part of Parkinson’s research at the moment – is that we have clinical trials ongoing for different techniques dealing with each of these three components.”
Dr Stott believes a cure may be found using a combination of treatments for the three targets. When it comes to stopping the disease, scientists are focused on halting the spread of a “rogue” protein called alphasynuclein. At least six trials in patients are under way worldwide to explore whether anti-protein vaccines could help, including some funded by the Michael J Fox Foundation.
In the UK, a £2.1 million trial funded by the National Institute of Health Research will start next year, studying whether a type of drug known as a cholinesterase inhibitor (CHEI) can help to reduce unsteadiness and improve concentration.
The area of research which has caused the most excitement is cell replacement therapy (CRT) – where dopamine cells grown from stem cells are transplanted into the brain. The treatment should help relieve the physical symptoms of Parkinson’s.
Human trials of CRT have been launched in the last few months in Japan, the US and Australia, while a European trial co-led by Cambridge University and Lund University, in Sweden, is expected to start next year.
Consultant neurologist Professor Roger Barker, who is leading the European project, says: “The idea behind cell replacement therapies is to literally transplant the cells into the brain to replace those which have been lost. If the dopamine cell-based therapies work in the way we expect, then I would be surprised if they’re not coming into clinic as a standard therapy in five to 10 years’ time. While it’s not a cure, it would transform the treatment of Parkinson’s.”
The momentum behind research has built up over the past two decades, with a “tsunami” of discoveries and developments in recent years. “Within a few years,” says Dr Stott, “we will see major progress. ”
But he cautions patients not to get their hopes up too early. “At this point, we want to keep patients informed, but not to raise expectations too much. If the trials don’t work, they will still further our understanding.
“But if they do… it’s Christmas Day.”
‘It’s a positive time for research because we can see so much of the jigsaw coming together’