This article will deal with the underlying causes of parkinsons disease, and will address new therapies which promise more effective treatment than traditional 'Drug Therapies'
Parkinson's Disease (PD) is a movement disorder characterized by tremors, muscular rigidity, restricted limb movements and walking with small, slow steps. It typically onsets around middle age, and although it is not fatal it is an ongoing degenerative disease, the process of which cannot be reversed. This article will deal with the underlying causes of PD and will address new therapies that promise more effective treatment than traditional 'Drug Therapies'.
What causes PD is not known, there may be genetic causality, but the main pathological process involves degeneration of the SUBSTANTIA NIGRA, which is situated in the basal ganglia and is an area rich in dopamine cells. Dopamine is one of the major neurotransmitters, or naturally occurring chemicals, found in the brain. In PD there is a major depletion of dopamine, especially apparent in the fiber projection from the substantia nigra to the corpus striatum. Dopamine is believed to be the main, but not the only, neurotransmitter involved in PD.
Decreased dopamine leads to secondary effects like degeneration of GABA receptors, and there is believed to be an interaction of dopamine with another neurotransmitter - Acetylcholine (Ach). While dopamine is depleted, acetylcholine (activity and production) is increased. It is the over activity of Ach which causes the tremors and rigidity which are the trademark symptoms of PD.
Traditionally, the symptoms of PD have been treated via drug therapy, the principal theory behind which involves reducing the activity of Ach (via an anticholinesterase e.g. scopolamine) or increasing the amount of dopamine (via the drug L-Dopa). The major problem with drug therapies however is that there are many, and often severe, side effects including nausea, dizziness etc. This is because the drugs often do not work on the specific areas where they are required (e.g. in the substantia nigra) but also in other areas of the brain where they are not needed. The other drawback is that although the drugs 'contain' the disease they do not 'cure' it.
New treatments have emerged involving neural graft therapy, where the emphasis is on encouraging new neurons to 'sprout' or grow in the damaged areas. There is now considerable evidence that neurons can sprout new synapses and fibers to replace those that have been lost. In neural grafting, preparations from fetal brain cells (esp. the substantia nigra in the case of PD) are transplanted, under surgery, into the damaged adult brain. Ethics are obviously an issue in this work, and recent researchers have attempted to find substitutes for human fetal cells by investigating if animal cells could also perform the same function.
The issue remains however that the surgeons are never sure if this operation will 'work' and that new dopamine cells will continue to grow and develop once the graft has been completed. If the causes of PD ARE genetic, no amount of grafting will have any long-term effects because the newly grafted cells will also become 'degenerative' due to the underlying genetic code. Much more research will be required before the underlying causes and an ultimate cure is found for PD, but new cloning research may provide the answers.
