It is the task of a psychiatrist to arrive at a diagnostic impression of an individual’s problems. The complexity of this pursuit derives in part from the overlap of psychiatric diagnoses. There are many psychiatric diagnoses and they are organized in categories in the Diagnostic and Statistical Manual (DSM), currently in its fourth edition. The first and second DSMs appeared in 1952 and 1968, and were respectively 132, 119 pages long. This contrasted with the DSM III, published in 1980, which was a more ambitious 494-page document presenting criteria for more disorders and in a more detailed fashion.

It is my impression that most psychiatrists thought or hoped that the categories were fairly distinct, but following its publication there came a myriad of research articles demonstrating the “co-morbidity” of one disorder with another to the point where it should be common knowledge that it is exceptional to find someone simply with one textbook DSM disorder. Thus individuals who come to psychiatrists or psychologists should not be exasperated when confronted with the complex overlap in diagnostic disorders. For example, clearly over­active behavior or inattentiveness in a five year old can be present in a number of disorders. Individuals who are diagnosed with Asperger’s Disorder are sometimes diagnosed with ADHD, Obsessive Com­pul­sive Disorder, Oppositional Defiant Disorder and other DSM disorders or non-DSM disorders like Sensory Integration Disorder, Non-Verbal Learning Disorder or Hyperlexia. They may have these disorders, or features of them which should be addressed in treatment, but it is important to recognize when Asperger’s Disorder is the primary diagnosis and that there are features of other disorders that are often associated with Asperger’s Disorder.
There are some other factors influencing the diagnostic process. Just as there are no fixed boundaries between many categories of diagnoses, there are no fixed boundaries between what is considered normal and what is not. Many psychiatric problems are a lack of or too much of some attribute. I defy anyone to look at the diagnostic criteria of our many psychiatric disorders and not think that they have some characteristics of some or several disorders. Most people have some problems paying attention or with organization and yet do not have ADHD. Peoples’ moods lie along a bell curve from profoundly de­pressed to excitedly manic. On the bell curve of levels of mood, one can be either low energy or high energy without either being depressed or manic. We have as much problem defining what we call abnormal and what we consider to be normal variation as we do differentiating one diagnostic category from another.

The complexity of the diagnostic process only reflects the complexity of the human brain. New brain imaging techniques demonstrate the interconnectedness of brain circuits that underlie our behavior. My impression is that if the brain were so organized that our categories of mental disorders were clearly delineated from one another and the diagnostic process was more straightforward, than human beings would never have landed on the moon.

The DSM-V is expected to be published in 2012. Mental health professionals anticipate and/or hope that it will remedy some or the shortcomings of earlier versions. In so doing it will benefit us and the patients that we serve.