Parkinson’s disease is due to the progressive degeneration of the neurones in the substantia nigra of the midbrain. This leads to deficiency of the neurotransmitter Dopamine, resulting in uninhibited random firing of the motor control neurons, causing the characteristic tremor seen in those affected with Parkinson's Disease (PD).
There are four primary features seen in PD:-
- Resting tremor, where limbs tend to exhibit a slight to moderate amount of uncontrollable movement when at rest
- Rigidity of the limbs, face, and trunk
- Bradykinesia, or slow movement
- Postural instability, or impaired balance
These all contribute to the gait disturbance seen in PD
There is also an accumulation of Lewy Bodies in Parkinson’s disease, these are abnormal aggregates of proteins within the neurones. Other neurotransmitters likely to be involved are MAO, GABA and Serotonin.
Symptoms resembling those of Parkinson’s disease have been described for thousands of years; There are citing’s from ancient Egypt, in the ancient Greek Illiad and in the Bible. In Ayurvedic Indian medicine, as far back as 500BC the condition was called “Kampavata”- meaning tremor, levodopa rich Macuna beans were used as a treatment.
The neurodegenerative condition was first officially described in 1817 by an English doctor, James Parkinson, when he published An Essay on the Shaking Palsy detailing the characteristic features which he called paralysis agitans, Charcot renamed the eponymous condition we know today as Parkinson’s disease.