Pathological Changes in Neurodegenerative Disease

From what has been sald so far it should be apparent that it is not really possible to draw clear cut qualitative distinctions, either in clinical or pathological terms, between the effects of so-called normal aging and those of the common neurodegenerative diseases of later life (i.e. AD, PD). Pathological diagnoses of AD and PD are made on the basis of the amount, rather than the type, and distribution of damage imposed upon the brain. In clinical terms this degree of damage may be represented by a subthreshold scoring on rating systems designed to test powers of memory or reasoning, or motor function. Such observations imply that aging and neurodegeneration might exist on a sliding scale of change the one inevitably leading, with time, into the other, with a certain and perhaps rather arbitrary “cut off point” separating the two.