Richard J. McNally

 

On his book What Is Mental Illness?

Cover Interview of March 16, 2011

The wide angle

Today’s approach to conceptualizing mental illness, embodied in DSM-IV, is subject to intensifying criticism from multiple quarters.  How did such a presumably flawed approach become so immensely influential?  The answer is that the approach has been successful in many ways, its flaws notwithstanding.

DSM-IV continues a radical break with psychiatric tradition, inaugurated by the appearance of DSM-III in 1980.  The first two editions of the DSM provided only sketchy, impressionistic descriptions of mental disorders, vulnerable to the subjective interpretation of different clinicians. In contrast, DSM-III provided objective, explicit criteria for defining each mental disorder.

For each diagnosis, DSM-III described each symptom so that clinicians interviewing the same patient could agree about its presence.  It specified the number of symptoms necessary for a patient to qualify for each diagnosis, and it eliminated any reference to Freudian or other speculative accounts of the causes of mental disorders.

The manual’s aim was to devise a descriptive, atheoretical lingua franca, to enable doctors of diverse clinical orientations to agree about the presence of a disorder even if they disagreed about its etiology.

By fostering improved reliability of psychiatric diagnosis, DSM-III enabled researchers to conduct valid research on the causes, correlates, and treatments of mental disorders.

For many years, clinicians paid little attention to diagnostic reliability. Those working under the sway of Freud, offered versions of psychodynamic therapy to a wide spectrum of patients whose problems they regarded as idiosyncratic symbols of unconscious conflicts, not symptoms of discrete disorders.

In the absence of effective treatments, reliable diagnosis doesn’t matter very much.  But as clinical scientists discovered that certain medications and cognitive-behavioral therapies tended to work better for some conditions than for others, the importance of getting the diagnosis right became increasingly important.

In view of these achievements of DSM-III, continued in DSM-IV, why are so many mental health professionals, as well as others, critical of the current atheoretical, descriptive system?

One reason is that the manual makes it difficult to formulate a principled boundary distinguishing mental disorder from normal mental distress.

To overcome this difficulty, some experts in psychopathology believe that a valid diagnostic system needs to appeal to factors beyond symptoms themselves as well as distinguish among symptomatically similar, but distinct, disorders.

Indeed, advanced branches of medicine conceptualize diseases in terms of causes (etiology) and the bodily dysfunctions (pathophysiology) that produce symptoms, and not by symptoms alone.  Many experts wonder whether exciting breakthroughs in genomics, neuroscience, and psychology may now permit us to abandon a purely descriptive approach in favor one grounded in advancements in basic science.