Discussing the clinical application of pharmacogenetics in Alzheimer's disease is complicated, because as things currently stand there is considerable professional debate over whether Alzheimer's disease exists as a separate clinical entity at all. Since at least the mid-1990s the relationship between Alzheimer's disease and other forms of dementia, such as Lewy body dementia or vascular dementia, has been in a state of flux: ‘Different forms of dementia are now known to have common underlying neuropathologies and histopathological studies have shown that mixed states (people presenting with features of more than one type of dementia) are probably more usual than pure dementia syndromes’ (Ritchie & Lovestone 2002: 1759). For many of my interviewees, ‘the dichotomy between vascular dementia and Alzheimer's Disease is probably artificial’ (CR 10). Yet in the clinic Alzheimer's disease is still treated as a separate condition. In the NHS, for example, while clinicians can prescribe drugs such as Aricept or Rivastigmine for patients suffering from Alzheimer's disease, they are discouraged from doing so for Lewy body and other kinds of dementia.

For clinicians, Alzheimer's is a progressive neurological disease leading to the permanent loss of cells in parts of the brain associated with higher functions.