Parkinson's, Alzheimer's, and motor neurone disease

Abstract
The label “neurodegenerative” is often used as an umbrella term for the distinct pathological conditions of Parkinson's, Alzheimer's, and motor neurone disease. However, there has been speculation that all three conditions represent different phenotypic expressions of a common aetiology.1 Calne and colleagues have argued that these diseases are examples of selective, premature decay of functionally related populations of neurones due to interactions between the environment and the aging process.2 Their two component hypothesis postulates that environmental insults, such as infection or neurotoxins, partially deplete selected neuronal populations, and that age related degeneration results in further neuronal loss beyond a threshold necessary for clinical disease. This model argues that age related cell death is a common contributory factor for all three diseases, although there may be specific environmental factors for each condition. Epidemiological …