Ontology of Psychiatric Conditions: Taxometrics
The author is nearly there, but they are lacking a few key pieces in their ontology and thus their language traps them by forcing them to conflate concepts that in fact need to be decoupled.<p>The required concepts are as follows
1. condition or underlying biological etiology   
2. diagnostic codes  
3. symptoms  
4. the patient  
5. the person assigning the code to a patient  
6. the impact of the symptoms on patient quality of life  (this one is nearly always left out, I left it out before I noted as I was wrapping up the post)<p>There are a number of relationships between these that I won&#x27;t go into in detail, but to give one example, there is &quot;some underlying condition may give rise to some symptoms.&quot;<p>The problem the author complains about is an inevitable artifact cause by discretization of underlying continuous variables into discrete categories. This is a direct consequence of signal detection theory and is why you see things described as spectrum disorders, because diagnostic codes are applied to sets of symptoms that are produced by multiple different underlying etiologies, including underlying conditions which would fall into the category of &quot;normal&quot; in the population. This is exacerbated by the fact that there is significant variability in how the person assigning the codes assesses the symptoms. An example example of this is that medical professionals consistently underestimate the amount of pain experienced by black Americans [1], and this is pain which is about is unambiguous as you can get.<p>The question then becomes, can we measure the various biases in these systems to try to recover what is really going on. Usually the answer is no. In the case of Alzheimer&#x27;s disease post mortem pathology is absolutely required in order for a diagnosis to be confirmed, and we don&#x27;t do enough autopsies to improve our models for mapping behavioral diagnosis to the pathology (which is definitional). This situation may improve over time, but as long as we cannot directly measure underlying etiology, those who may or may not suffer from an underlying condition will continue to be subjected to the current, clearly inadequate, system.<p>1. <a href="https:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pmc&#x2F;articles&#x2F;PMC4843483&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pmc&#x2F;articles&#x2F;PMC4843483&#x2F;</a>