Date：2021-05-21

What Is Parkinson's Disease?

Parkinson's disease is a chronic neurodegenerative disease. Its symptoms include non-motor symptoms (such as autonomic dysfunction, sleep disorders, and cognitive disorders) and core motor symptoms (namely tremors, bradykinesia/slow movements, rigidity, and abnormal/unstable gait and posture). These symptoms in Parkinson’s disease are due to a loss of nerve cells in the brain, leading to insufficient dopamine levels. Dopamine acts as a messenger for parts of the brain and nervous system which help co-ordinate body movement; a lack of dopamine thus means that certain parts of the brain cannot function as well as it should, subsequently manifesting as the aforementioned symptoms.

What Is Parkinsonism?

Parkinsonism refers to the clinical syndrome characterized by the four core motor symptoms (comprising of tremors, bradykinesia/slow movements, rigidity, and abnormal/unstable gait and posture) typical of Parkinson’s disease. However, Parkinsonism is an umbrella term which does not solely apply to Parkinson's disease, as these motor symptoms can also present in many disorders other than Parkinson’s disease. Examples of these diseases include – but are not limited to – Lewy body dementia, amyotrophic lateral sclerosis, frontotemporal dementia, and multiple system atrophy.

Symptom Overlap Between Classic Parkinson's Disease And Atypical Parkinsonism

As previously established, the four core motor symptoms typical of Parkinson’s disease can also present in many other disorders, with atypical Parkinsonism referring to this set of overlapping symptoms. Specific examples of these symptom overlaps include autosomal recessive inherited juvenile Parkinson’s disease (early onset) with incidences of dystonia, multiple system atrophy with autonomic dysfunction, progressive supranuclear palsy and corticobasal degeneration with irregular eye movements, and amyotrophic lateral sclerosis / Parkinsonism-dementia complex of Guam with motor neuron abnormalities.

Getting Correctly Diagnosed

Because of the overlapping symptoms of Parkinsonism, it is difficult to accurately diagnose individuals by clinical symptoms alone. In addition, the pathogenic principle is different, which makes it more difficult for doctors to diagnose. It is thus important for doctors to use various instruments such as CT, MRI, and/or genetic testing to assist in the correct diagnosis of cranial nerve diseases according to the individual’s condition. A correct and swift diagnosis is crucial such that the adverse effects of the disease can be better prevented and mitigated.

Reference materials:

Zhang P, Chen Y, Zhang C, et al. Genetics of Parkinson’s disease and related disorders. Journal of Medical Genetics 2018;55:73-80.