How effective are personalised drug treatments for treating Parkinson’s Disease? – Maria Munden

Parkinson’s Disease is a progressive neurological condition, affecting approximately 145,000 people in the UK alone. The main symptoms of Parkinson’s include tremors (the most common), balance issues, anosmia (loss of sense of smell), nerve pain, urinary incontinence, dysphagia (difficulty swallowing) and dementia (progressive memory loss).

It is generally unknown as to why people get Parkinson’s, but what we currently know is that the cause is mainly due to the loss of nerve cells in an area of the brain called the substantia nigra, which are responsible for producing dopamine, a chemical messenger that controls and coordinates body movement. We can therefore conclude that Parkinson’s sufferers lack dopamine, leading to the symptoms previously mentioned such as tremors and balance issues.

Past research has suggested that your risk of developing Parkinson’s Disease is due to a combination of genetic and environmental factors. Environmental risk factors include pesticides and herbicides used in farming and traffic or industrial pollution, which could contribute to nerve cell death. In terms of genetic factors, some sufferers carry a very rare mutation (change in DNA base sequence) that directly causes the disease. These mutations include those in these genes: alpha synuclein, parkin, PINK1, DJ-1, ATP13A2, PLA2G6, FBX07 + VPS35. However, a change in the LRRK2 gene is the most common genetic variant linked to Parkinson’s, with 1% of sufferers carrying it, and a 70% chance of carriers succumbing to the disease by the age of 80. This mutation is also more common in certain ethnic backgrounds such as North African and the Jewish population.

Dr Heather Mortiboys, Dr Laura Ferraiuolo and Professor Winston Hide, based at the Sheffield Institute for Translational Neuroscience (SiTRaN) here at the University of Sheffield, in collaboration with the University of Oxford, lead a project which has identified two different abnormal mechanisms that underpin development of the disease. They took skin biopsy samples from two large groups of patients with the common sporadic form of Parkinson’s Disease and transformed them into the type of nerve cells that would be affected in the disease (those in the substantia nigra).

They found that the two groups displayed either mitochondrial or lysosomal dysfunction. This would affect how cells produce energy and how they would handle waste products. This suggest that mitochondrial and lysosomal dysfunction are likely to contribute towards the progression of Parkinson’s Disease. The most crucial point here though is the fact that the dysfunctions were also found in the transformed nerve cells, showing that new drugs can be tested on these cells to look for effectiveness. The results of this study will help Scientists to understand how to develop new personalised drug therapies for neurodegenerative diseases, so not just Parkinson’s, but also Alzheimer’s Disease and Motor Neuron Disease.

But what do we mean by personalised medicine? Personalised medicine is a way of medicating patients which moves away from the “one size fits all” approach. The process of personalising medication arrives from the individual characterisation of underlying cause of the disease (informed by genomics + other clinical information), which then allows for tailored treatment to match an individual’s genetic makeup, environmental risk factors and responses. This provides a much more effective course of treatment which will have fewer side effects.

Personalised medicine is an important consideration for “single multifactorial” pathology-driven conditions such as Parkinson’s Disease. “Single multifactorial” means a single disease that can have many factors causing it. In the case of Parkinson’s, this can be mutations in particular genes, along with environmental factors.

So personalised medicine is relevant to Parkinson’s Disease given the multiple pathology culminating in a complex motor and nonmotor disorder. The problem with current medications is that they are known as “monotherapies”, which means that they only alleviate one symptom/cause e.g. tremors. As we know already, Parkinson’s is a multifactorial condition, so monotherapies have failed to stop the progress of the disease. A good analogy is to imagine a roof with 20 holes in it. Fixing just one of those holes isn’t going to do a whole lot is it? So personalised medicine is highly likely to be effective as it could potentially tackle multiple symptoms at a time as well as the underlying causes, tailored to each individual.

With a continually ageing population, it seems like personalised medicine is going to be most effective in drastically reducing the number of deaths from devastating neurodegenerative disease.

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