What is Parkinson's Disease?
Parkinsonism is the term used to describe the syndrome of tremor, muscle rigidity, bradykinesia and abnormalities of gait. Parkinson's Disease (PD) is the most common cause. However, there are many other causes that include drugs (most commonly neuroleptic drugs used to treat schizophrenia and other psychotic illness and antiemetic drugs such as Metoclopramide (Maxolon) and Prochlorperazine (Stemetil).
Further causes include encephalitis (inflammation of the brain), toxins (MPTP, carbon monoxide and manganese), dementia (Lewy Body, Alzheimer's and vascular), trauma (punch drunk syndrome or dementia pugilistica), diseases such as Wilson's disease, which results in deposition of copper in the brain and other degenerative diseases of the brain including Multiple System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP).
PD is due to degeneration and loss of nerve cells in many parts of the nervous system with the motor signs and symptoms relating to damage in an area of the brain called the substantia nigra. This is associated with a deficiency of the neurotransmitter dopamine and an accumulation of inclusions (round deposits) called Lewy Bodies containing a protein called Alpha - synuclein.
The underlying cause of PD is not known. A number of factors have been implicated in causing similar neurological clinical presentations and these include: -
- Toxins - these include MPTP (1-methyl-4-phenyl-1, 2,3,6-tetrahydropyridine), a synthetic opiate contaminant and certain pesticides.
- Genetic factors - about 15% of people have a first degree relative with PD although the mode of inheritance has not been clearly established.
- Ageing - the cells of the substantia nigra decline at about 5% per decade. It is thought that this decline, in association with environmental factors, may result in the increased incidence of PD with age.