Defining “mental illness” has vexed researchers for more than a century. Are mentally ill people just different from others in the larger group? If so, I’d be classified as mentally ill when compared to my immediate family because I like long-distance running and don’t play a musical instrument, and my son would be mentally ill because he doesn’t like math and science.
Clearly there must be more to it than that. The American Psychiatric Association, in its bible, the Diagnostic and Statistical Manual of Mental Disorders (or DSM, for short), devotes hundreds of pages to describing and cataloging mental disorders. This is the guide psychiatrists and clinical psychologists use to help diagnose disorders, but it has been subject to constant revision, and its definition of mental disorders has changed over the years as well. Early versions even considered homosexuality to be a “disorder.”
Now the current guide, the DSM-IV, is being revised again. The DSM-V is scheduled to be released in 2013, and one of the key areas slated for change is the definition of “mental disorder.” The problem is, even the DSM acknowledges that defining a mental disorder is an imprecise science. The current version includes as part of its definition a consideration that there is no definition of the term that covers all situations—and no one is suggesting that disclaimer be removed.
Last week, psychology graduate student (and Research Blogging Psychology / Neuroscience Editor) Jason Goldman held a mini-carnival, an online forum inviting some of the top psychology and neuroscience bloggers to weigh in on the question “What Is Mental Illness?”
British psychologist and editor Christian Jarrett answered the question by citing an editorial published in January in Psychological Medicine. The editorial’s writers, led by Dan Stein, argued that a “mental disorder” has five primary factors: It’s a behavior or pattern occurring in an individual, causing clinically significant distress or impairment, reflecting an underlying physical dysfunction, and is not primarily the result of social deviance or conflicts with society. It’s also not just a response to a stressful event like a friend or family member’s death, where it’s normal to expect someone to appear “depressed” or otherwise disturbed for a period of time. Stein’s team is part of the working group for the DSM-V, so clearly their arguments will carry significant weight in forming the new definition.
One of the biggest changes in their proposed definition is the statement that a mental disorder “reflects an underlying psychobiological dysfunction.” They are, in essence, saying that there is nothing truly “mental” about these disorders—the disorders are a result of physical problems in the brain. This is a huge acknowledgment for a field that once thrived on such vacuous concepts as the “id” and the “superego.” The anonymous neuroscience blogger “Neurocritic” suggests that these specific, neurological underpinnings are the best way to describe mental illnesses. Neurocritic cites a new effort by the US National Institute for Mental Health (NIMH) to define disorders based not only on their symptoms, but across several domains, including genes, neural structures, and behaviors. Using this line of reasoning, traditional definitions of mental disorders are flawed because they fail to address the mechanism of the illness. Doctors don’t define a broken leg as “unable to walk,” so why should psychiatrists define a mental disorder solely based on the behavioral symptoms?
Just as “unable to walk” may be due to any number of underlying problems, mental illnesses defined in the DSM have significant overlap. Neurocritic points to the case of borderline personality disorder (BPD): 85 percent of the patients suffering from the condition also meet the criteria for at least one other disorder, including anxiety, intermittent explosive disorder, and substance abuse. Could it be that the symptoms of “BPD” are usually explained by some other condition? Or that what psychiatrists now see as five separate disorders might actually only be caused by two or three underlying psychophysiological problems? The NIMH project is in its early stages, and is expected to take nearly a decade to complete, but it may offer a more useful way of addressing the problem of mental illness than the DSM model.
Even as the definition of mental illness changes, there will always be difficult borderline cases. Indeed, the DSM-IV specifically notes that even physical disease can be difficult to define. For example, some people with treatable deafness prefer not to have their hearing restored, and a person who is abnormally short or tall might consider that to be a benefit. Similarly, some mental “disorders” become a part of who a person is. Does it make sense to treat a child for, say, ADHD, if their personality is changed so much as to make them a very different person? While distress and impairment are part of the definition of mental disorders in the current DSM, if we redefined these disorders based on their underlying physical causes, then what would we do about people who are comfortable with who they are?
Because of perplexing issues like these, publication of the DSM-V has been delayed, with sections and recommendations being released for commentary at intervals along the way. The hope is that ultimately, the final document will better reflect the consensus of the psychiatric community. Unfortunately, whenever the document is finally released, it probably still won’t tell me if I’m crazy for wanting to run a marathon, or if my son is insane to pursue his dream of becoming a rock star.
Dave Munger is editor of ResearchBlogging.org, where you can find thousands of blog posts on this and myriad other topics. Each week, he writes about recent posts on peer-reviewed research from across the blogosphere. See previous Research Blogging columns »
Originally published November 17, 2010