Parkinson’s Disease (PD)

Definition

Parkinson’s disease is a progressive brain disorder that causes shaky movements or tremors. Typically, the disease impairs or slows down movements due to abnormal brain functioning. Owing to the tremors as a typical symptom, it is also known as shaking palsy. Unstable gait makes walking difficult and at a later stage, even speech may get affected. Parkinson’s disease is typically late-onset and usually appears above 50 years of age. It is the second most common debilitating condition, after Alzheimer’s disease that affects elderly people. Although the disease remains incurable, the quality of life could be improved with medication.

Symptoms

Symptoms often go unnoticed in the initial stage of Parkinson’s disease. The signs may appear on one side of the body and gradually spread to other half. Typical signs of Parkinson’s disease are:

  • Shaking or tremors of hands or head even at rest
  • Stooping posture and non-coordinated walking
  • Loss of finer movements
  • Slow, jerky movements due to muscular rigidity or stiffness
  • Loss of unconscious movements like smile or facial expressions
  • Difficulty in initiating movements or swallowing
  • Confused mental status, depression or memory loss

The signs and symptoms are considered specific for this disease. Therefore, related spectrum of movement disorders is termed parkinsonism. Similar movement disorders due to causes other than Parkinson’s disease are called secondary parkinsonism.

Parkinson’s disease may present severe complications including:

  • Difficult breathing, bowel movements and sexual dysfunction.
  • Hallucinations, memory loss and other cognitive problems.
  • Having a family history of the disease makes an individual more vulnerable. Men are more likely to develop Parkinson’s disease than women.

Causes

Brain cells that regulate movements use a chemical, dopamine, to communicate among themselves. Occasionally due to the death of dopamine-producing cells, the dopamine level falls. Low dopamine levels dampens the communication between the brain cells and impairs the functioning of specific brain region controlling movement. As a result, the muscular coordination and activity gets affected.

The actual cause behind the loss of dopamine cells is unknown. However, the drop in dopamine level is progressive and is correlated with the gradual increase in severity of the symptoms. Postmortem studies of the PD patients have reported the presence of protein clumps, called Lewy bodies. Among other proteins, the Lewy bodies contain huge deposits of alpha-synuclein protein that are not broken down and therefore, get accumulated in the cell. Although the exact reasons are not clear, genetic defects and environmental factors serve as common triggers of Parkinson’s disease.

Treatment

The death of dopaminergic cells is an irreversible process and therefore, the main aim of the treatment is to manage the symptoms. Rescuing the normal dopamine level by an external supply of dopamine is considered as the most effective therapeutic regimen. As dopamine could not enter the brain directly, precursor of dopamine, levodopa (L-DOPA), is recommended that could easily cross the blood-brain barrier.

Levodopa is the best existing medication for Parkinson’s disease. Agonists that mimic the functions of dopamine also prove effective in controlling the symptoms. Although the symptoms subside with treatment but over the time a resistance towards these medications develops.  Regular physical and mental exercises reduce the risk of the appearance of symptoms at old age.

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