After a 14-year revision process and a lot of contentiousness, the latest version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) debuts May 22. What changes will affect psychologists?

The new manual reflects the wealth of research and knowledge researchers and clinicians have generated since the last revision, says James H. Scully, MD, medical director and chief executive officer of the American Psychiatric Association, which publishes the DSM. "Our hope is that by more accurately defining disorders, diagnosis and clinical care will be improved and new research will be facilitated to improve our understanding," he says.

The updated DSM incorporates new findings while taking into account mental health professionals' need for consistency, says Chris Hopwood, PhD, an assistant professor of psychology at Michigan State University. "There's been a tension between the desire to move ... toward more evidence-based models on the one hand and the need to not disrupt clinical practice as it stands," says Hopwood, who will be presenting workshops on the DSM-5 at APA this April and at various state psychological associations throughout the year.

While the American Psychiatric Association isn't revealing all the changes until the new manual is out, here are some of the previews the association has already shared:

  • A developmental focus. The DSM-5 re-orders disorders according to the age they're most likely to appear, beginning with neurodevelopmental disorders that occur most often in childhood and ending with disorders associated with old age, such as neurocognitive disorders. The disorders' descriptions also describe how they may present differently throughout the life span.

  • New diagnostic criteria. Some of the diagnostic criteria will change. A new disorder called autism spectrum disorder, for example, collapses what were previously four separate disorders — autism, Asperger's disorder, childhood disintegrative disorder and pervasive developmental disorder — into one with different levels of symptom severity. Similarly, the DSM-5 eliminates the previous version's four subtypes of schizophrenia. And the section on bipolar disorders now emphasizes changes in activity and energy as well as mood during manic and hypomanic episodes as a way of facilitating earlier detection and increasing diagnostic accuracy.

  • A move toward "dimensional" measures. While the DSM-5 still lists separate disorders, the new manual will also incorporate dimensional measures of severity for many disorders. That shift is based on the realization that the lines between many disorder categories blur over the life span and that symptoms attributed to a single disorder may also appear in other disorders, just with different levels of severity. With the new autism spectrum disorder, for example, clinicians can choose among three levels of severity in the dimensions of social communication and interaction and repetitive behavior and interests. That shift represents a first step toward thinking about psychopathology in a new way, says Hopwood. "There hasn't been much evidence that disorders are categorical, both in terms of being categorically distinct from each other and from normal behavior," he says. The reason so many people have more than one psychiatric disorder is because many disorders reflect problems in the same dimension, or system, he says, adding that this approach means thinking about what disorders have in common instead of what makes them different.

  • Increased emphasis on culture and gender. The DSM-5 will also feature greater attention to cultural factors that may affect diagnosis. In addition to tools for cultural assessment, a new section will describe common cultural syndromes, how they are expressed and possible causes. The new information will not only encourage clinicians to take into account such individual differences, but will help standardize such information across clinicians, says Hopwood.

  • A new section on areas that need further research. The DSM-5 will include three sections: an introduction with instructions on using the manual, a section with diagnoses and diagnostic criteria and a new section with information on conditions that require additional research before they can be incorporated into the official diagnoses.

  • A commitment to more frequent updating. The switch to an Arabic numeral in the manual's name is more than just a design change, says Hopwood. "The idea is that there will be versions 5.1, 5.2 and 5.3 and that these sorts of mini-editions can come along more frequently than they had in the past so that the manual can be more responsive to research as things unfold," he says.

  • Inclusion of International Classification of Diseases (ICD) codes. The DSM-5 includes equivalent ICD-9-Clinical Modification (CM) codes and equivalent ICD-10-CM codes. As of Oct. 1, 2014, the ICD-10-CM will become the official health classification of the U.S. government, says psychologist Geoffrey M. Reed, PhD, senior project officer in the World Health Organization's Department of Mental Health and Substance Abuse. "That means ICD-10-CM codes will be required for all electronic health care transactions, such as billing and reimbursement," he says. And unlike the DSM-5, which costs $199, the ICD-10-CM is available free at the National Center for Health Statistics website, he adds.

For Hopwood, that last point suggests an interesting question: Why does the field need two diagnostic systems?

"It's obviously inefficient to have two different systems for diagnosis — one for the United States and one for the rest of the world," he says. "One wonders whether there is really a need, frankly, for the DSM given the ICD."

There are other concerns with the DSM-5, as well. Many within the mental health community expressed strong concerns about the process and the anticipated revisions, says Rhea K. Farberman, executive director for public and member communications at APA. While APA did not take an official position on the DSM-5, it did encourage members to lend their expertise to the process. In a December 2011 statement, APA's Board of Directors expressed concerns about the potential harm any diagnostic system can have if it increases the potential for over-identification of illness and therefore the possibility of unnecessary treatment. APA called upon the DSM-5 Task Force to adhere to an open, transparent process based on the best available science.

For more information, visit the American Psychiatric Association's DSM-5 website.

Rebecca A. Clay is a writer in Washington, D.C.