Abstract

The evolution of a relevant nosological concept reflects changes in the distinction between what is recognized and defined as normal and pathologic. Attention is directed to the rationale and value of detecting subclinical aging-related modifications in cognitive performance. The position that different kinds of dementias may have precedents in etiological-specific kinds of early or mild cognitive impairments (MCI) supports targeting people earlier for study of these subclinical symptoms. Because heterogeneous disorders can be expected to have multiple patterns of cognitive and behavioral changes, useful conceptual nosologies should be flexible. Yet clinical research primarily restricts its focus to a single pathway where MCI leads to Alzheimer's disease (AD), and uses selective recruitment, washout screenings, repeated trialing of similar compounds, and other methods that bank the published evidence in favor of the existing therapies and their modest efficacy. This focus on AD recursively colors MCI, not as a flexible "human kind" in need of more careful research, but like AD, as an essential "natural kind." Early determination of MCI targets a potential pharmaceutical market of a quarter to a half of the population over sixty-five and the individual experiencing cognitive decline in its early stages is aware and sensitive to their surroundings, to a linked sociodegeneration with neurodegeneration. This paper examines how classifying people changes both the classifier and the subject of classification. The potential for conflict of interest is raised regarding what new causal knowledge and techniques for ascertainment are selected. Reading evidence from epidemiology, neurology, and clinical studies through science studies and bioethics lenses, we explore the possibility of a pluralistic model of cognitive impairment nosology where biological/pathologic processes respond and interrelate with a normal healthy state.