Introduction

The syndrome of parkinsonism, defined as akinesia accompanied by rigidity, and often tremor, occurs more frequently as people grow older and may be present in a significant proportion of elderly people (Mayeux et al.1992, Bennett et al. 1996, Meara et al. 1997). Two-thirds of patients with the diagnosis of Parkinson's disease (PD) will be over the age of 70 years, though the proportion of parkinsonism not due to PD increases with age. A further important issue in the care of the elderly with PD is that many patients, particularly women, will be living alone or will be cared for by a spouse who may also suffer from limitations imposed by health problems. The frailty of the diagnosis of parkinsonism and PD is addressed in Chapter 2, the epidemiology of parkinsonism in Chapter 7 and the drug treatment of PD in elderly subjects in Chapter 9.

The neuropathological basis of PD

PD is characterized by cell loss and gliosis in a paired brain stem nucleus called the substantia nigra (Jellinger 1986, Forno 1996). The substantia nigra is a pigmented dopamine rich nucleus that forms part of five closely related deep-seated subcortical brain nuclei, collectively called the basal ganglia (caudate, putamen, globus pallidus, subthalamic nucleus and substantia nigra). The substantia nigra consists of a densely cellular pars compacta, and a less cellular pars reticulata. The neurones in the substantia nigra pars compacta project to the caudate and putamen (together called the striatum) forming the nigrostriatal tract.