Parkinson's Disease

Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder that primarily affects the motor system. It is characterized by the progressive loss of dopaminergic neurons in the substantia nigra, a region of the midbrain. The disease is named after James Parkinson, who first described it in "An Essay on the Shaking Palsy" in 1817.

Pathophysiology

The hallmark of Parkinson's disease is the degeneration of dopaminergic neurons in the substantia nigra pars compacta. This leads to a significant reduction in dopamine levels in the striatum, a critical component of the basal ganglia involved in motor control. The loss of dopamine results in the characteristic motor symptoms of Parkinson's disease.

In addition to dopaminergic neuron loss, the presence of Lewy bodies, which are abnormal aggregates of the protein alpha-synuclein, is a pathological feature of Parkinson's disease. These inclusions are found in various regions of the brain and are thought to contribute to the disease process.

Symptoms

The primary symptoms of Parkinson's disease are motor-related and include:

• Tremor: Often described as a "pill-rolling" tremor, it typically occurs at rest and is one of the most recognizable symptoms.
• Bradykinesia: Slowness of movement, which can make everyday tasks difficult and time-consuming.
• Rigidity: Increased muscle tone leading to stiffness and resistance to movement.
• Postural instability: Impaired balance and coordination, which can lead to falls.

Non-motor symptoms are also common and may include:

• Cognitive impairment and dementia
• Mood disorders such as depression and anxiety
• Sleep disturbances
• Autonomic dysfunction, including constipation and orthostatic hypotension

Diagnosis

Diagnosis of Parkinson's disease is primarily clinical, based on the presence of characteristic motor symptoms. There is no definitive test for Parkinson's disease, but imaging techniques such as DaTscan can support the diagnosis by showing reduced dopamine transporter activity in the striatum.

Treatment

While there is no cure for Parkinson's disease, several treatments can help manage symptoms:

• Medications: The most common treatment is levodopa, often combined with carbidopa to enhance its effectiveness. Other medications include dopamine agonists, MAO-B inhibitors, and COMT inhibitors.
• Surgical interventions: Deep brain stimulation (DBS) is a surgical option for patients with advanced Parkinson's disease who do not respond adequately to medication.
• Rehabilitation: Physical therapy, occupational therapy, and speech therapy can help manage symptoms and improve quality of life.

Prognosis

Parkinson's disease is a progressive disorder, and symptoms typically worsen over time. The rate of progression varies among individuals. While the disease itself is not fatal, complications such as falls, pneumonia, and infections can lead to increased mortality.

Research

Ongoing research in Parkinson's disease includes studies on the genetic and environmental factors contributing to the disease, the development of neuroprotective therapies, and the potential use of stem cells and gene therapy.

Also see

• Neurodegenerative disorders
• Dopamine
• Basal ganglia
• Deep brain stimulation
• James Parkinson