Krishnan (2007), in a discussion of the concept of disease in geriatric psychiatry, made the case for uniting descriptive syndromal (nominal) diagnosis with essential diagnosis (i.e., diagnosis of the related and presumably causative biological processes). The designation of certain signs and symptoms as indicators of disease paves the way for rational understanding and rational treatment.

However, what is rational depends on the dominant cultural ideology. If deviations from the expected norm of behavioral or physical function are related to whims of the gods or to transgressions against them, rational treatment is placation of the proper deity or deities. If the deviations are due to an imbalance of bodily fluids or humors, attempts to rebalance by bleeding or purging make sense.

What is rational in the age of molecular biology? Should not diseases be seen in essentialist terms as disturbances at a molecular level and labeled accordingly? Should not the offending underlying process be elucidated and repaired by genetic manipulation or by altering the structure, function, or interaction of the proteins encoded by those genes? Would it not be more reasonable to speak of Alzheimer disease in one person as a cerebral amyloidopathy associated with homozygosity for the e 4 allele of apolipoprotein E, and in another as a cerebral amyloidopathy associated with an overload of amyloid precursor protein processing due to reduplication of the 21q22 band of chromosome 21?

Specificity is gained in this process of essentialistic molecularization, but something is also lost, and that is the clinical picture of the disease that leads to its diagnosis and a confounding of associated molecular mechanisms with etiology. Thus far, the e4 allele and Alzheimer disease are only associated; a causal chain has not been established. In the case of Down syndrome, the link is still largely associative; not all persons with 21q22 reduplication develop clinical Alzheimer disease. These molecular diagnoses do not explain why that person began to manifest this disease in this way at this particular point in time.

It is likely that the closest we can come to resolving the behavioral-molecular polarity is to make them stand together, as has already been done with the phrase “due to” following the psychiatric syndromal diagnosis in DSM-IV-TR. The “due to” portion of the diagnosis has the potential for further elucidating etiology, but we must be careful that it does not also further cloud our vision.

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Myron F. Weiner, M.D.
Clinical Professor of Psychiatry and Neurology,
Aradine S. Ard Chair in Brain Science,
Dorothy L. and John P. Harbin Chair in Alzheimer’s Disease Research,
University of Texas Southwestern Medical Center at Dallas, Texas
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