Richard J. McNally

In a nutshell

Nearly half of Americans have suffered from mental illness at some point in their lives. One quarter has been mentally ill during the previous year. These figures come from the finest survey research available, funded by the National Institute of Mental Health. Is madness, then, rampant in America?

The answer depends on what we mean by “madness.”

The term brings to mind schizophrenia—a psychotic disorder involving a break from reality and marked by delusions and hallucinations. Yet what counts as mental illness spans far more than psychosis. Many more people suffer from anxiety disorders, depression, and substance abuse than from schizophrenia.

Nevertheless, the sheer numbers of Americans reported to suffer from mental illness still seem implausibly high. Which implies that our system of diagnosing people may often mistake the normal emotional problems of everyday life as mental illness.

This system, embodied in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders, known as DSM-IV, provides the criteria for over 360 different forms of mental illness. Immensely influential, the DSM-IV determines eligibility for reimbursable treatment, provides the foundation for clinical research, and sets the boundary between normality and abnormality in American society.

The DSM is the flashpoint of growing critical attention—especially because the American Psychiatric Association (APA) is currently debating proposals for revising it. The next edition is due to appear in 2013.

In What Is Mental Illness?, I provide an accessible, but nuanced, guide to the current controversies regarding how we conceptualize mental illness. The book covers cutting-edge theory and research from evolutionary psychology, genomics, psychology, history, and cross-cultural psychiatry—to weigh the merits of proposed solutions of how best to draw the boundary between mental distress and mental disorder.

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.

A close-up

In chapter one, I tell the story of how the recent controversy regarding the meaning of mental illness erupted.

Chapter two addresses whether we are pathologizing everyday life. I focus on the boundary problem—the difficulty distinguishing distress from disorder within our current system. I consider how economic and political forces tug at this boundary, affecting how we understand sexual dysfunction, depression, social anxiety disorder, and posttraumatic stress disorder (PTSD) reportedly arising from watching televised images of the 9/11 terrorist attacks, for example.

Asking whether evolutionary psychology can make sense of mental disorder, in chapter three, I analyze an influential approach to conceptualizing mental disorder as harmful dysfunction in evolved psychobiological mechanisms of the mind. Noting the limits of this approach, I suggest a promising revised version.

In chapter four, I scrutinize attempts to solve an apparent evolutionary paradox: If mental disorders are heritable, common, and harmful, why hasn’t natural selection eliminated genetic variants predisposing to disorder from the population? I show how two theorists have provided a convincing solution to this puzzle.

Chapter five provides an analysis of social constructionist approaches to mental disorder. Social constructionist theorists question whether mental health professionals discover mental disorders in the same way as nonpsychiatric physicians discover infectious diseases. They suggest instead that social processes, not biological ones, shape or create mental disorders. Drawing on historical and cross-cultural scholarship, I show how these theories vary in plausibility, depending on the disorder.

In chapter six, I cover the fast-moving field of psychiatric genomics, illustrating how it is changing our understanding of the role of genes in risk for mental illness.

In chapter seven, I draw on recent work in psychology and philosophy of science designed to answer whether mental disorders differ by kind or degree.

Closing the book, chapter eight provides some provisional answers to the driving question—What is mental illness?

Lastly

What is mental illness?

There is no sound-bite answer to this question. We will never have a clear-cut set of criteria that identifies all instances of mental disorder and excludes everything else.

The reason for this is that we do not discover mental illnesses in nature as scientists have done with the elements of the periodic table.

Nevertheless, there are facts about how the mind/brain produces psychiatric symptoms, and these are discoverable by science.

Ideally, science can illuminate what has gone with a person and can inform us about what treatments will work best to fix it. These facts provide the basis for sound arguments about where to draw the boundary between distress and disorder even though social, political, cultural, and economic factors will always play a role in this process.