Mild Cognitive Impairment: Kinds, Ethics, and Market Forces

In their article, Graham and Ritchie (2006) robustly confront the term mild cognitive impairment (MCI). They contrast a "real" diagnosis of Alzheimer's disease (AD) with a potentially spurious human invention called MCI. They argue we should not push MCI and AD too close together, lest MCI catch too much of the reflected reality it does not deserve. I agree with their purpose, but suspect their argument is not as clear cut as we might hope.

Classification is fundamental to the human activity called science. It is reflected also in the way we allocate and refine words. Classification allows us to determine the usefulness of terms, to share meaning, and hopefully to predict. MCI is an attempt at classification in this manner.

The first problem is the clarity of definition. Graham and Ritchie imply that others see MCI as a precursor to dementia. At times they fall prey to this belief themselves. But is this what MCI claims? This link to AD and its recursive coloring of MCI is central to their argument. It seems that many hope that MCI is a term for "at risk of dementia." This confusion hampers much of the debate. The current operationally defined nosological criteria specify MCI is not dementia. This means that MCI can not be dementia without changing the criteria for one or both. At present, the evidence does not support this. Those people with MCI who will go on to develop dementia cannot reliably be distinguished from those who have a defective memory for other reasons. In the meantime, the link between MCI and dementia of various types is a valid area for investigation. Graham and Ritchie should have more confidence that usefulness can be determined by science and that this will triumph in the end.

Modern psychiatry is very keen to believe it is naturalistic. Everything can be measured and will soon be explained by physical laws. However, Graham and Ritchie point to the intrusion of human concepts and values that may be shaping the way we measure the natural world. They invoke the term human kind to differentiate this activity from natural kinds. Psychiatry has always struggled to connect its diagnoses to naturalistic ideas of pathology and etiology. It could be argued that psychiatric nosology has always been susceptible to the creations of humans. Another modern invention—early psychosis—has parallels with the MCI story. But as the Rorschach test shows, most of us continue to see shapes in what really is only an inkblot. If the shape is something we really want to see, expect, or have been trained to look for, so much the better. A definable precursor state to dementia (or schizophrenia) would make us all happy, not just those insatiable shareholders. However, the earlier in the unfolding of degenerative dementia we go, the less reliable and valid are our clinical diagnoses.

Graham and Ritchie say MCI is a human kind, unlike Alzheimer's disease, which is an essential natural kind. The authors argue that the purported relationship between MCI and AD feed back in a loop to give MCI a natural kind standing that it does not yet deserve. They examine the underlying social processes that support this firming of an as yet insubstantial concept. These include the desire for patients and their doctors to have hope and pharmaceutical companies to have markets and profits. They invoke a mythical authorized person who can determine a diagnosis as a newly formed kind after a common act of recognition. Using kind in this context appears to refer to a thing rather than a term. But it is the term that is being socially validated, not the thing. AD is a more socially validated term than MCI, but its relationship with reality remains humanly constructed.

Does the invocation of kinds aid this argument? A kind is not really what it appears. A kind is a term to describe a concept that humans hold about the world. Therefore, dividing kinds into various types, such as natural, human, and practical, betrays the inevitable human...