Diagnosis is one of the most challenging aspects of clinical practice
in psychiatry. Despite centuries of study and the clarity of terminology
brought by the Diagnostic and Statistical Manual (DSM), the boundaries
of psychiatric disorders remain indistinct and overlapping. Though many
patients clearly fit the behavioral definitions of the current system,
many do not. Often patients have symptoms of multiple disorders or seem
to fit in the margin between definitions rather than squarely in any
one category. Schizoaffective disorder spans schizophrenia and bipolar
disorder; ADHD blurs into childhood bipolar disorder; anxiety disorders
and mood disorders co-exist. These are just a few of the dilemmas facing
the practicing psychiatrist every day.
Of greater practical importance, current diagnoses have limited ability
to predict prognosis and treatment response. Diagnoses may change over
time. Treatments are primarily directed at symptoms or syndromes such
as depression or psychosis rather than diagnoses. As a result, patients
may go for years until the correct diagnosis is made.
These problems are particularly acute for patients suffering from bipolar
disorder, where diagnosis is frequently difficult and for which there
are specific medications called mood stabilizers. A study of the Depression
and BiPolar Support Alliance (DBSA) membership indicated that bipolar
patients on average go seven years and see three to four doctors
before the correct diagnosis is made. During this time, they suffer
from the uncertainty of their diagnosis. They may also inadvertently
be treated inappropriately. Once a diagnosis of bipolar disorder is made, patients
still frequently may require trials of several medications over several
years before the optimum regimen is determined.
The limitations of psychiatry’s current diagnostic system result
in large part from not being based on etiology, or the causes of disease.
In other areas of medicine, diagnoses based on collections of symptoms
or syndromes have given way over time to diagnoses based on etiology.
For example, jaundice once was a diagnosis. Now it is considered
a syndrome that may result from many different possible etiologies from
viral hepatitis to tumor or alcohol. Biological tests are used to pinpoint
the etiology-based diagnosis.
In the absence of a detailed knowledge of biological etiology, diagnoses
in psychiatry have been based upon behavioral syndromes. Advances in genetics
now are providing new understanding into the biological and molecular bases
of psychiatric illness. Though genes may explain only half of psychiatric
etiology and interact with environment, genetics promises a new biology-based
approach to diagnosis.