What Is Parkinson’s Disease?
Parkinson’s disease is a neurodegenerative disease. It affects the nervous system and is marked by the loss of dopaminergic neurons in a brain region called the basal ganglia, especially in a part called substantia nigra [1, 2, 3].
Parkinson’s disease belongs to a group of diseases called hypokinetic diseases, which are diseases in which the affected individual loses the ability to move [4].
The loss of neurons in Parkinson’s disease is caused by the accumulation of a protein called alpha-synuclein. When this protein is accumulated, it forms Lewy bodies. These Lewy bodies then cause the loss of dopaminergic neurons in the basal ganglia [1, 2, 3, 5].
Interestingly, Lewy bodies can cause other neurodegenerative diseases such as Lewy bodies dementia [5].
Parkinson’s disease happens usually sporadically, however, around 5-10% of all the cases are due to inherited mutations in genes like LRKK2, VPS35, Parkin, PINK1 and DJ-1 [6].
Symptoms of Parkinson’s Disease
Parkinson’s disease is a hypokinetic disease, causing a variety of movement disorders. These include:
- Tremors – Patients suffering from Parkinson's disease often experience uncontrolled shaking of the hands.
- Akinesia - Akinesia is defined as the loss of the ability to move voluntarily. For example, a person with akinesia may take a long time to execute a movement, and they sometimes fail to execute it at all.
- Muscle Stiffness – Feeling rigid on the muscles.
- Balance and coordination problems – Usually, we observe troubles with balance, coordination and a snooped posture.
The symptoms of Parkinson's differ from other conditions affecting movement, and there are significant differences between the symptoms of Parkinson's and diseases like Huntington's disease or ALS [1, 2, 7].
What are The 5 Stages of Parkinson’s Disease?
The build-up of alpha-synuclein and the formation of Lewy bodies is a progressive process. Therefore the symptom severity worsens with the disease progression.
Stages of Parkinson’s Disease
Stage 1: Mild Motor Symptoms
In the early stages of Parkinson’s disease, we observe very mild symptoms. These are often hard to notice and consist of movement symptoms such as mild tremors or muscle stiffness.
Stage 2: Advanced Motor Symptoms
In this stage, the symptoms of Parkinson’s disease are more obvious. The patient experiences tremors, muscle stiffness and even changes in facial expressions and speech difficulties. We might even notice changes in the posture of the patient. The symptoms may start appearing on both sides of the body. Although the symptoms are worsening, the patient can live independently.
Stage 3: Severe Motor Symptoms
In this stage, the symptoms are usually the same as in stage 2, however, the patient may experience falling, loss of balance and slowness of reflexes. We observe slow movements, but the patient is cognitively fine and can continue independent living.
Stage 4: Loss of Daily Independence
In the later stages of the disease. the majority of the people require assistance for daily living. This is because the ability to move independently becomes significantly hard for these patients. In addition, their reaction times are significantly slower.
Stage 5: Late Stage: The End-Stage of Parkinson’s Disease
This is the final stage of the disease. where 24-hour assistance with daily activities is required. The patient loses the ability to stand and walk due to muscle stiffness. Patients at this stage in addition to the symptoms of Parkinson's disease may experience dementia, hallucinations and delusions.
However, it is important to note that the disease itself is not lethal.
Treatment for Parkinson’s Disease
Treatment of Parkinson’s disease consists of dopamine precursor L-DOPA, dopamine agonists, monoamine oxidase type B inhibitors (MAOB) and Catechol-O-methyltransferase (COMPT).
L-DOPA was the first ever proposed medical treatment for Parkinson’s disease and helps with managing the symptoms of the disease. COMT inhibitors are used with L-DOPA and prolong L-DOPA effects.
MOAB inhibitors inhibit the breakdown of dopamine in the brain which ultimately increases dopamine’s availability.
In addition to these, deep brain stimulation is used to treat Parkinson’s disease. It consists of a surgical implantation of two electrodes in the brain, which stimulate subcortical structures. This stimulation helps with managing symptoms of Parkinson’s disease [10, 8, 9].
It is important to note that these treatments are not perfect and researchers are actively investigating different options for the treatment of Parkinson’s disease [9].