Parkinson’s disease

Published on 03/03/2015 by admin

Filed under Neurology

Last modified 03/03/2015

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Parkinson’s disease

Definition

Parkinson’s disease (PD) is a progressive neurological condition, resulting from the degeneration of dopamine-producing neurons located in the substantia nigra, part of the basal ganglia (S2.11).

Epidemiology

Prevalence

The prevalence worldwide is estimated to be 4 million. In the UK, the incidence is 1 in 500 people.

Ethnic background

The condition occurs in all ethnic groups.

Age

The mean age of presentation is 65 years with peak onset between 55 and 65.

Gender

There is a 1.8 times greater risk of PD in men than in women.

Aetiology

Most people with PD are described as having idiopathic PD (having no specific known cause). The definitive cause of PD remains uncertain but is thought to result from a genetically determined vulnerability to particular environmental factors.

Environmental factors

Toxins

Symptoms of PD have been associated with long exposure to certain toxins/chemicals, such as pesticides and metals (e.g. manganese or iron).

Recreational drug abuse

Opioid-based recreational drugs have also been found to produce Parkinsonism type symptoms.

Head trauma

An increased risk of developing PD has been highlighted in those who have experienced a severe head injury compared with those who have never suffered a head injury. However, whether the head trauma is contributory to or a consequence of PD is still inconclusive.

Genetic

While genetic influences may also contribute to the development of PD, it is thought to be the cause in only a small minority of cases.

Pathology

The symptoms of PD result from the loss of pigmented dopamine-secreting (dopaminergic) cells in the pars compacta region of the substantia nigra (SN). Initially, cell damage appears to occur following an excessive accumulation of iron, which is toxic to nerve cells. The outcome is oxidative stress resulting in significant damage to the proteins, lipids and DNA of the cell. A defect in the transport proteins within the cell finally leads to an abnormal accumulation of proteins (alpha-synuclein) termed a Lewy body.

Outcome and prognosis

The dopaminergic neurons of the SN project to the striatum and normally modulate the activity of both the direct and indirect pathways within the basal ganglia (S2.11

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