By Dr Ananya Mandal, MD
Parkinson’s disease is not yet curable. Several classes of drugs have been found that reduce the symptoms. Numerous researchers are working towards understanding the pathophysiology and developing new therapy targets for the disease.
Some of the notable areas of Parkinson’s disease research include:-
Stem cell therapy in Parkinson’s disease
Researchers, led by a team at the University of Edinburgh have successfully used skin samples from a patient to create brain nerve cells. This could help scientists understand the actual cause behind death of the brain’s neurons. It will also make it easier to test new drugs which could slow or halt progress of the disease.
The researchers, working in collaboration with University College London (UCL) and funded by a £300,000 grant from the charity Parkinson's UK have pioneered in stem cell development and use in the disease. The aim is to eventually find drugs that can prevent the death of neurons.
Much has been studied to detect the genes that can raise the risk of developing Parkinson’s disease. In a large genetic study five new common risk genes have been discovered, bringing the tally of genetic susceptibility genes to 11. The researchers found that presence of these specific genes raised the risk by 2.5 times. Assuming a prevalence of Parkinson's of 0.14% in the general population, the risk would increase to 0.35% in the highest risk group.
Yet another study by US researchers showed that the immune system may have a key role in the development of Parkinson's disease. In their 20-year study of 4,000 people, half with Parkinson's disease, the team of researchers found an association between genes controlling immunity and the diseased condition.
Gene therapy has been studied widely in the treatment of Parkinson’s disease.
A recent clinical trial by US researchers has shown success with gene therapy. The small study in The Lancet Neurology used a virus to add genes to brain cells. This caused improvement in symptoms in half of patients.
The procedure involves using a non-infectious virus to carry the gene into a part of the brain called the subthalamic nucleus (STN). The gene used leads to the production of an enzyme called glutamic acid decarboxylase (GAD). This is the enzyme that catalyses the production of a neurotransmitter called GABA. GABA acts as a direct inhibitor on the overactive cells in the STN. Patients with Parkinson's have reduced levels of a chemical - GABA – in their STN.
Neuroprotective treatments have been researched in detail. These agents could protect neurons from cell death and slow the progress of the disease. Agents currently under investigation as neuroprotective agents include anti-apoptotic drugs (CEP 1347 and CTCT346), lazaroids, bioenergetics, antiglutamatergic agents etc.
Others that have been used include monoamine oxidase inhibitors selegiline and rasagiline, dopamine agonists, and the complex I mitochondrial fortifier coenzyme Q10.
Nutrients and others
Nutrients have been tried in clinical trials in patients with Parkinson’s disease. The L-dopa precursor L-tyrosine was shown to relieve an average of 70% of symptoms. Ferrous iron, the essential cofactor for L-dopa biosynthesis was shown to relieve between 10% and 60% of symptoms in some patients. Efficacy has also been noted with THFA, NADH, and pyridoxine—coenzymes and coenzyme precursors involved in dopamine biosynthesis.
Research has shown that people who take ibuprofen on a regular basis have a lower risk of developing Parkinson's disease. In studies of more than 135,000 men and women regular users of ibuprofen were 40% less likely to develop Parkinson's. But like all NSAIDs, ibuprofen can cause worrying side effects, like an increased risk of gastrointestinal bleeding.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)