The DSM-5 Is Moving Aware From IQ Scores
A major change to the description and organization of criteria for autism and related disorders tops the major revisions clinicians can expect to see for neurodevelopmental disorders in DSM-5, to be published in May.
The chapter on neurodevelopmental disorders, the first set of criteria appearing in Section 2 of the manual, also includes the addition of “social communication disorder,” reorganization of criteria for learning disorders, and changes to the criteria for intellectual disability (known in DSM-IV as mental retardation). The appearance of the chapter on neurodevelopmental disorders at the beginning of Section 2 reflects the developmental—or “lifespan”—approach taken by the DSM-5 Task Force to the organization of the text: disorders more frequently diagnosed in childhood appear at the beginning of the manual and disorders more common to older adults (such as neurocognitive disorders) appear at the end.
Possibly the most significant change—and certainly one that received much public scrutiny—is the consolidation of DSM-IV criteria for autism, Asperger’s, childhood disintegrative disorder, and pervasive developmental disorder-not otherwise specific (PDD-NOS)—into one diagnostic category called autism spectrum disorder (ASD). That change reflects the fact that much research has indicated a lack of concordance across clinical centers treating autism in how the four DSM-IV diagnoses have been applied.
“The DSM-5 Neurodevelopmental Work Group spent a great deal of time evaluating the reliability and validity of the separate DSM-IV diagnoses and concluded that there was no evidence to support continued separation of the diagnoses,” Susan Swedo, M.D., chair of the Work Group on Neurodevelopmental Disorders, told Psychiatric News.
The new criteria describe “deficits in social communication and social interaction” and “restrictive and repetitive behavior patterns”—the two principal symptoms associated with ASD—along with an expanded number of specifiers. The latter can be used by clinicians to specify features of the disorder with which some individual patients may present, such as if the autism is accompanied by intellectual impairment or is associated with a known genetic/medical or environmental/acquired condition.
In addition, the criteria include three levels of severity for both principal symptoms to indicate the level of supportive services required by an individual patient. The three levels are “requiring support,” “requiring substantial support,” and “requiring very substantial support.”
For instance, for the symptom of “deficits in social communication and social interaction,” a patient requiring “very substantial support” would be one who has “severe impairments in functioning, very limited initiation of social interactions, and minimal response to social overtures from others.” Similarly, for “repetitive/restrictive behaviors” a patient requiring very substantial support would be one who exhibits inflexibility of behavior and extreme difficulty coping with change, as well as “great distress/difficulty changing focus or action.”
Swedo noted also that the DSM-5 criteria indicate that symptoms must be present in the “early developmental period,” reflecting research that has shown the disorder is evident as early as age 24 months.
Related also to recent research on autism is the inclusion of a new diagnosis, social communication disorder, designed to capture children who have severe deficits in social communication and interaction but who lack the restrictive and repetitive behavior patterns necessary for ASD. These children have typically been diagnosed with PDD-NOS. (A goal of the task force in developing the manual has been to reduce the use of NOS diagnoses to classify patients who do not fit into more explicit diagnostic categories.)
The criteria describe “persistent difficulties in the social use of verbal and nonverbal communication” in four areas: using communication for social purposes such as greeting or exchanging information; changing communication to match context or the needs of the listener; following rules for conversation or storytelling, such as taking turns in conversation; and understanding what is not explicitly stated and nonliteral or ambiguous meanings of language. The impairments result in “functional limitations in communication, social participation, social relationships, academic achievement, or occupational performance” that are not explained by the presence of ASD or another mental or general medical condition.
“We believe social communication disorder will capture those children who have in the past been diagnosed with PDD-NOS as a way of drawing attention to the patient’s social communication impairments despite the absence of restrictive interests and repetitive behaviors,” Swedo told Psychiatric News.
Also significant is the consolidation of separate learning disorders that had appeared in DSM-IV—reading disorder, mathematics disorder, and disorder of written expression—into one diagnosis called specific learning disorder. The criteria describe difficulties in learning and academic achievement as indicated by the presence of at least one of six symptoms persisting for six months. The new criteria now include specifiers for reading, written expression, and mathematics.
Swedo said an advantage of the DSM-5 criteria is that they are much more comprehensive. Clinicians can use these criteria to diagnose deficits in all three areas that tend to occur together and that affect learning and academic achievement, with detailed specifiers identifying the relative deficit levels in each area.
Finally, some important changes have been made to intellectual disability (identified in DSM-IV as mental retardation). The name change aligns DSM with federal legislative language and with that used by U.S. professionals specializing in the disorder.
Most importantly, the DSM-5 criteria mark a move away from relying exclusively on IQ scores and toward using additional measures of adaptive functioning. DSM-IV criteria had required an IQ score of 70 as the cutoff for diagnosis; the new criteria recommend IQ testing and describe “deficits in adaptive functioning that result in failure to meet developmental and sociocultural standards for personal independence and social responsibility.”
The new criteria also include severity measures for mild, moderate, severe, and profound intellectual disability.
Swedo explained that forensic psychiatrists consulting with the work group had testified to the problematic nature of using IQ scores alone for diagnosis. They have sometimes had to assess someone with an IQ of, say 71, as not having intellectual disability in the presence of severe deficits in adaptive functioning—because the IQ score alone gave a false impression of their judgment capacity—therefore making that person eligible for the death penalty.
“Moving away from a specific number and incorporating functional testing is going to be very helpful to clinicians in matching diagnosis to individual patients,” she said. ■