ABSTRACT
Parkinson’s disease (PD) is a disease of elderly people with age-specific prevalence rates steeply increasing into extreme old age. In cross-sectional studies two-thirds of subjects with PD will be aged over 70 years old. PD results from dopamine deficiency in a part of the basal ganglia in the forebrain called the corpus striatum (caudate nucleus and putamen). This deficiency state arises from cell death in a large pigmented mid-brain nucleus called the substantia nigra that provides critical dopaminergic input to the basal ganglia via the nigrostriatal tract. With progression PD can affect many parts of the brain and peripheral nervous system. Surviving neurones contain typical inclusions called Lewy bodies. PD is primarily a disorder of voluntary motor control. There is a particular difficulty in the appropriate execution of automatic learnt motor plans.
