The British physician James Parkinson first described Parkinson’s disease as “the shaking palsy” in 1817. Parkinson’s disease is a non-contagious degenerative brain disorder that involves the deterioration and death of nerve cells/neurons leading to a loss of function and synchronization of electrical impulses.
Parkinson’s disease is a chronic and progressive disorder that primarily affects muscle and movement. However, approximately 20% will develop dementia in varying degrees of severity within 10-15 years from an initial Parkinson’s diagnosis.
Parkinson’s disease is the 2nd most common neuro-degenerative disease after Alzheimer’s disease. Although significant research progress has been made in the last decade, the exact cause of Parkinson’s disease is still not fully understood.
The Importance of Dopamine
Dopamine is a neurotransmitter (chemical messenger) that facilitates messaging between nerve cells. The brain converts the amino acid tyrosine to dopa, and in turn, this is converted to dopamine. It is sometimes referred to as the ‘happy hormone’ as increased levels are associated with pleasure and reward.
Dopamine affects the nervous system and is essential for both good physical and mental health i.e. body and mind. A vast array of functions depend on it, examples include mental facility, mood, pain, movement, blood vessels, heart rate, the immune system, as well as kidney and pancreas function.
Dysfunctions of the dopamine system leads to too little or too much being produced. The outcome of this can be serious and possibly life threatening. It appears that an imbalance of dopamine plays a role in a range of conditions such as addiction, ADHD, Schizoprenia, Tourette’s syndrome, Alzheimer’s disease, obesity as well as Parkinson’s disease.
Dopamine and Parkinson’s Disease
The brain stem, in particular the midbrain structure the substantia nigra (“black substance”), is significantly affected by a high rate of cellular death of dopamine secreting cells. As a result, one of the 4 neural Dopamine pathways in the brain, the nigrostriatal pathway (associated with movement), experiences a significant decrease in dopamine function.
As noted in Parkinson’s disease diagnosis, brain changes other than a lack of dopamine are associated with the disease. These include low norepinephrine levels (neurotransmitter and hormone), as well as protein clumping and the presence of Lewy bodies observed in autopsy.
The collective term Parkinsonism applies to a group of disorders whose similar symptoms result from degeneration and death of nerve connections that produce dopamine. Parkinson’s disease is the best known form of Parkinsonism and is therefore referred to as Idiopathic Parkinson’s disease (no known cause) or Primary Parkinsonism. The other forms of Parkinsonism include those whose condition is the result of another neurological disorder or the cause is suspected or known.