Parkinson's Disease

Parkinson’s disease is a common chronic degenerative disorder of the central nervous system. It is a disabling disease of the ageing population and affects mobility and locomotion. It is classified as a movement disorder. The motor symptoms of Parkinson’s disease results from progressive damage of dopamine-generating cells of “substantia nigra”, of the basal ganglia, a part of the brain situated below the cerebral cortex and is called the mid-brain.

Parkinsonian syndromes can be divided into two types according to their origin:

  1. Primary or idiopathic, where the cause of cell death is not fully understood; and 
  2. Secondary or acquired, where the disease can be linked to various kindsof offending agents such as drugs, toxins, infection, tumor etc.

Idiopathic Parkinson’s disease can have a hereditary basis or it can be sporadic in nature. A related group of disorders “Atypical Parkinsonism” represents wider distribution of the process of degeneration involving other critical areas of the brain. One of the diseases in this group is known as multiple system atrophy.


The content of this module has been validated by Dr A.B. Dey, Department of Geriatrics, All India Institute of Medical Sciences on 10/4/2015

The three most important symptoms are:
  1. Rest tremors: Uncontrollable shaking of a limb or a part of the body is known as tremor. Tremors usually begins in the hand or arm. It is more likely to occur when the limb is at rest and can be more noticeable when the patient is stressed, anxious or tired.
  2. Bradykinesia or slowness of movements: It is another characteristic feature of PD which is associated with difficulties along the course of the movement process, from planning to initiation and finally execution of a movement. Common examples of bradykinesia are slow speed doing a task, difficulty in turning on bed, dressing etc. 
  3. Muscle stiffness or rigidity: Stiffness and resistance to limb movement is known as rigidity and is caused by increased muscle tone, an excessive and continuous contraction of muscles.
Related to these three major symptoms is gait and posture impairment, which includes freezing of gait, postural instability and falls.  Other motor symptoms include:
  • Mask like face
  • Reduced eye blink
  • Soft voice
  • Dysphagia
  • Dyskinesia or involuntary muscle cramps.
In addition, patients with Parkinson’s disease have several distressing non-motor symptoms. These include:
  • Mood disorders: depression
  • Sleep disturbance
  • Cognitive impairment or dementia
  • Sensory symptoms such as loss of smell sensation, pain etc.
  • Fainting
  • Disturbance of bowel and bladder 
  • Sexual dysfunction.


Parkinson's disease/ Parkinsonian syndrome is caused by a loss of nerve cells in the part of the brain called the substantia nigra. Nerve cells in this part of the brain are responsible for producing a chemical called dopamine. Dopamine acts as a messenger in the nervous system, and helps control and co-ordinate body movements. If these nerve cells become damaged or die, the amount of dopamine in the brain is reduced. This means that the part of the brain controlling movement cannot work so well, which causes movements to become slow and abnormal. The loss of nerve cells is a slow process. The level of dopamine in the brain falls over time. Only when 80% of the nerve cells in the substantia nigra have been lost, will the symptoms of Parkinson's disease appear and gradually become more severe. Most people with Parkinson's disease have idiopathic disease (having no specific known cause). Possible factors associated with the Parkinson's disease are:

  1. Familial occurrence in small number of patients
  2. Environment factors have been associated with an increased risk of Parkinson's including:
     i. Pesticide exposure
     ii. Head injuries
     iii. living in the rural area or farming
     iv. Air pollution related to road traffic


Diagnosis of Parkinson's disease is essentially a clinical diagnosis from information derived from medical history and neurological examination. There is no imaging or laboratory test that can identify the disease. Brain scans are sometimes used to rule out disorders that could give rise to similar symptoms

There is no curative treatment for Parkinson’s diseases and related syndromes as their basic cause is uncertain. Symptomatic improvement for motor symptoms includes levodopa (usually combined with a dopa-decarboxylase inhibitor or COMT inhibitor), dopamine agonists and MAO-B inhibitors.

Two stages are usually distinguished:

In initial stage individual with PD develops some disability for which he needs pharmacological treatment. In the later stage the patient develops motor complications related to levodopa usage.

Treatment in the initial stage aims for an optimal control between symptoms and side-effectsresulting from improvement of dopaminergic function. The start of levodopa (or L-DOPA) treatment may be delayed by using other medications such as MAO-B inhibitors and dopamine agonists, in the hope of delaying the onset of dyskinesias.

In the second stage the aim is to reduce symptoms while controlling fluctuations of the response to medication. Sudden withdrawals from medication or overuse have to be managed.

Surgery: When medications are not enough to control symptoms, surgery and deep brain stimulation can be of use. In the final stages of the disease, palliative care is provided to improve quality of life.


There is no definitive preventive strategy for Parkinson’s disease. Healthy life style and early diagnosis are helpful in disability limitation and care planning. There are reports from large epidemiological studies suggest that a few life style factors provide protection against the disease. However, these are not recommended for prevention of Parkinson’s disease.

Caffeine consumption appears to be protective against Parkinson's disease, though the exact mechanism is not clearly understood. 

Journal of Alzheimer’s Disease 20; (2010) S221–S238DOI 10.3233/JAD-2010-091525

Although tobacco smoking decreases life expectancy and quality of life, it may reduce the risk of PD. The protective effect is more related to duration than quantity.  This may be the effect of nicotine as a dopamine stimulant.


Front Aging Neurosci. 2015 Jan 9;6:340. doi: 10.3389/fnagi.2014.00340. eCollection 2014.

  • LAST UPDATED ON : Feb 04, 2016


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