Parkinson’s disease was first identified over 200 years ago, and today is the second-most common neurodegenerative disease affecting 2-3% of the population over 65 years of age. It presents as uncontrollable movements, such as shaking, stiffness and difficulty with balance and coordination. Ordinarily, symptoms are mild at first and gradually worsen over time. These physical symptoms can be accompanied with physiological changes including mental and behavioural changes, depression and memory difficulties.

Diagnosis largely relies on the presence of bradykinesia (the slowness of movements) and other motor symptoms; however, Parkinson’s disease is associated with many other non-motor symptoms which contribute to overall disability.

What is the cause of symptoms?

Observation of Parkinson’s patients shows a loss of specific neurons in a small section of the brain. This specific area of the brain is responsible for the control of body movements, learning, mood, judgement, and decision-making. As a result of this loss of neurons, there is a deficiency of dopamine. Typically, dopamine plays an important role in regulating the movement of the body, hence why a reduction in dopamine is largely responsible for many of the symptoms of Parkinson’s disease. The cause of the loss of neurons is currently unclear – but a combination of genetic and environmental factors is thought to be responsible.

Also observed in Parkinson’s disease is the build-up of α-synuclein. It is a protein which accumulates as fibrils in the brains of people with the disease. The deficiency of dopamine, build-up of α-synuclein and many other cell types throughout the nervous system are all thought to be involved from the beginning of the disease onwards. Patients can also lose the nerve endings which are responsible for generating a neurotransmitter and hormone called norepinephrine, which controls heart rate and blood pressure. This may help explain some of the non-motor symptoms, such as fatigue and a sudden drop in blood pressure when standing up.

Research developments:

Currently, treatment options for Parkinson’s disease are limited, with most aiming to restore dopamine levels. Despite these attempts, they do not the symptoms of the disease which are not associated with dopamine, such as cognitive impairment and other non-motor features. As our understanding increases, more therapeutic avenues are emerging. Some aim to control the symptoms of the disease without generating side effects associated with current treatments available.

As we previously discussed, the build-up of the α-synuclein protein is thought to have a central role in Parkinson’s disease. An experimental approach looking at preventing the spread of the protein uses antibodies to break it down. This would mean that it cannot spread to neighbouring cells. immunisation against the protein have been shown to have neuroprotective effects – but only in animal models. Clinical trials in humans are currently emerging, where its effectiveness can be evaluated.

Alternatively, a drug currently being used to target the dopamine deficiency in Parkinson’s disease is called safinamide. In a clinical trial involving 669 patients with moderate to advanced Parkinson’s disease, it showed an improvement of motor scores, as well as an improvement in depression and communication scores. This particular drug is now becoming more widely available for clinical use.

An increase in the knowledge of Parkinson’s disease has led to new avenues for new treatments, and it is highly likely that the management and treatment of the disease will continue to progress in the coming years.

Will Parkinson’s disease ever be curable?

With current knowledge of the disease, it is unlikely that the disease will be curable in the near future. This is not to say that with continuous scientific developments that a cure will not be found years into the future. However, with the full nature of the disease currently not understood, medications are the best option to help manage the symptoms and improve quality of life. There is a wide range of therapeutic options available, each aiming to improve quality of life for the patients suffering with this disease. Treatments are constantly improving, providing hope for Parkinson’s disease patients and their families.