At present, there are no disease-modifying drugs approved for patients. All of the currently prescribed medications (and approved surgical interventions) treat the symptoms only and do nothing to halt disease progression. However, there are a number of potentially disease-modifying treatments currently in clinical trials, at various stages of clinical development, with results emerging all the time and some highly anticipated results expected over the next few years.
A “cure” for Parkinson’s disease will likely be a combination of different treatments for people at different stages of the Parkinson’s disease process, and even for those who do not (yet) have it. Indeed, different therapeutic strategies can be applied in different circumstances.
Preventing the development of Parkinson’s disease through removal/mitigation of environmental factors (e.g., banning the herbicide paraquat, which has been linked to Parkinson’s disease, or protecting against head knocks) and lifestyle interventions like regular exercise and coffee drinking has the potential to reduce the incidence of new cases of Parkinson’s disease. Although strictly not therapies or treatments, such interventions in people without Parkinson’s fall into the category of healthy brain ageing strategies. Indeed, coffee drinking is strongly associated with a reduced risk of Parkinson’s disease, while exercise has been shown to improve motor symptoms in patients with early-stage Parkinson’s in addition to its effect on healthy brain ageing.
For those already diagnosed, there are three different types of treatment that collectively might comprise a ‘cure’:
The good news is: significant progress is currently being made in clinical studies across all three types of “cure”.
Therapies that can slow or stop progression of disease will add years of ‘health-span’ and improve quality of life in those with prodromal (a medical term for the period when the earliest signs and symptoms are observed) or early-stage Parkinson’s. Professor Curtis’s current work can potentially help us identify these people sooner, while some of the therapies being tested in clinical trials at the moment, including a number of agents that target the protein alpha-synuclein, which plays a key role in the development of Parkinson’s, have the potential to slow or stop progression. Such agents, if successfully found to stop (or slow) the disease from progressing, can help us protect the remaining vulnerable neurons in the brain that are key to controlling movement.
For those with mid- to advanced-stage disease, there has already been significant loss of neurons, so therapies for these patients need to compensate for this loss, either through cell replacement (via transplantation) or by providing additional support to the remaining neurons (e.g., via delivery of GDNF or other “neurotrophic factors”). Most likely, it will be a combination of these approaches that provides success.
A number of groups are currently investigating stem cell transplants (one new trial of this approach is now getting underway in the UK and Sweden) and delivery of neurotrophins to the brain. Neurotrophins are basically neuroprotective agents that support neuronal survival and function; these provide a nurturing environment for cell replacement therapies to succeed. One big step forward in the latest studies of neurotrophins is the use of viral vectors to deliver these supportive factors to the brain–far less invasive than the approaches (e.g., via implanted catheter) used in previous trials.
There is unlikely to be a ‘silver bullet’ therapy that will fit everyone; what is required is a personalised approach that focuses on individual needs (depending on where people are in the disease course). The goal is to get the right treatment to the right person at the right time to stop, slow or reverse the natural course of Parkinson’s.
Professor Maurice Curtis and Professor Sir Richard Faull inspect a brain.
Prestigious British medical journals provide a state of play on Parkinson’s research and ask “what next”?
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Could wearable devices one day be used to predict who might go on to receive a Parkinson’s diagnosis? Quite possibly. Machine learning models fed movement data recently did just that.
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A 62-year-old man with late-stage Parkinson’s and severe gait impairments regains the ability to walk normally following experimental treatment in Switzerland.
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