As chairman of the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) Work Group on Attention Deficit Hyperactivity Disorder (ADHD) and Disruptive Behavior Disorders, I read the article on ADHD that appeared on the front page of The New York Times on April 1, 2013, with interest and also dismay, which was shared by my colleagues in the work group. We recognize the effort involved in the preparation of this story and the need for attention to the important problem of ADHD. However, we must correct errors in the presentation of the role that DSM might have had in an increase in ADHD prevalence, real or otherwise, as well as the mischaracterization of the careful discussions in the DSM-5 work group about minimizing false-positive diagnoses.
As repeatedly noted in the article, the Centers for Disease Control and Prevention (CDC) study suggests that a higher proportion of the population is currently being given the diagnosis of ADHD than before. It is essential to distinguish population prevalence (which might not have changed) from rates of case identification and treatment (which might have changed). However, even the second possibility could only be shown if compared against an earlier study that used a similar sample, similar ascertainment procedures, and similar definition of the disorder in question. The CDC study asked parents whether they had ever been told by a doctor or other health professional that their children were suffering from any of several named diagnoses, including ADHD, but not the qualifications of the person who had provided that diagnosis or whether the diagnosis had led to treatment. The absence of a comparable base is not mentioned, although an increase in rates of diagnosis is inferred by quoting an increase in the cost of medication used for ADHD—a less valid marker of quantity than either the number of prescriptions written or the number of recipients. In any event, the data cannot be attributed to changes pending in DSM-5. Data collection for the CDC was completed in June 2012, nearly a year before the DSM-5 criteria were due to be released.
Despite these limitations, one could be forgiven for concluding that the end result of a rising rate of ADHD diagnoses will be an increase in the number of older youth who will become substance abusers. However, evaluation of ADHD treatments in the largest and most carefully conducted treatment study of any child psychiatric diagnosis (the MTA study) showed no evidence of a greater risk for substance abuse at 11-year follow up among those treated with medication compared to those treated with psychotherapy or with no treatment.
Aside from our concerns regarding the CDC study, the work group is eager to dispel misrepresentations included in the NY Times article regarding DSM-5. The article states that, in DSM-5, “Criteria for the proper diagnosis of A.D.H.D. …have been changed specifically to allow more adolescents and adults to qualify for a diagnosis…,” that “…most proposed changes would lead to higher rates of diagnosis,” and that the changes “will allow the diagnosis in individuals who display symptoms of A.D.H.D. but continue to function acceptably in their daily lives.” The specific DSM-5 changes referred to are: 1. raising the required age of onset; 2. inclusion of examples of how symptoms might be observed in older adolescents and adults; and 3. eliminating the requirement that the symptoms must cause “impairment.” Below we discuss each of these “changes.”
1. Increasing the required age of onset for symptoms to age 12 or earlier (previously age 7 or earlier). This change was based on an extensive literature review showing conclusively that, even when the features of ADHD are noted to be present before age 7, when the individuals are older, they will generally report that the onset of their disorder was at a later age. The findings mean that if the age of onset reported by the patient or his/ her family is after age 7, then there is a strong possibility that a true case of ADHD would be erroneously overlooked. Prospective studies have confirmed the difficulties that patients and family members have in accurately remembering age of onset. Other studies indicate that 96 percent of lifetime cases of ADHD are captured with an onset by age 12 to 14, suggesting that an age 12 cutoff is superior to most alternatives. Careful consideration was given to the potential of an unintended increase in prevalence that might result from this change. To examine this possibility, a subcommittee of the work group analyzed and published data from a British birth cohort, with findings suggesting that the impact on prevalence will be negligible.
2. Inclusion of additional examples of how symptoms typically look in older adolescents and adults. The ADHD symptom criteria (including the examples), beginning with DSM-III, were originally designed to apply to elementary-school-aged children. Given that we now know that ADHD often persists into adolescence and adulthood, continuing to confine the examples to this age group was inappropriate and confusing to clinicians. While it is conceivable that adding to the examples available could result in changes in how the symptoms are rated or applied, this was thought not to override the benefits of more developmentally appropriate examples, in view of the fact that the wording for the symptoms themselves remained unchanged and there was no change in diagnostic reliability in the DSM-5 field trials. These examples should make it easier for clinicians to see the applicability of the criteria across the lifespan, rather than resorting to guesswork. It should also increase reliability and it is unlikely that prevalence will increase as the diagnosis requires multiple criteria, childhood onset, and an impact on functioning. Further, the text in DSM-5 will clearly state that ADHD begins in childhood, and its placement in the chapter of “Neurodevelopmental Disorders” will further emphasize that this disorder begins in childhood.
Related to this, the DSM-5 will lower the number of symptoms required to assign the diagnosis to older adolescents and adults. A number of follow-up studies of adults who were diagnosed with ADHD as children have recently been published that show that adults with persistent ADHD symptoms that negatively impact their lives and occupation have fewer symptoms than they had had as children. Based on these findings, we reduced the number of criteria necessary for the diagnosis in adults only. A purely mathematical approach would have required us to lower the number required from 6 to 4 symptoms, but because of the ever-present concern of false positives we applied a more conservative threshold of 5 symptoms. When we applied this revised threshold to national survey data sets, the increase in rate of adult disorders was very small.
3. Elimination of required impairment. Contrary to what was stated in the article, the DSM-5 will require impairment before assigning the ADHD diagnosis, although the wording of this has been changed to: “There is clear evidence that the symptoms interfere with, or reduce, the quality of social, academic, or occupational functioning.”
To conclude, the CDC findings may speak to misdiagnosis by health care professionals who are not carefully following the current DSM diagnostic criteria. Since DSM-5 has not yet been published, none of the findings in the CDC relate to this upcoming edition. We also disagree that changes that will be included in DSM-5 will add to this problem. The CDC numbers reported actually strengthen the importance of finding ways of clarifying the diagnosis of ADHD while respecting its complexity, for example, by using carefully standardized rating scales. Several of these exist, and one will be included in DSM-5. We can only hope that the misleading inferences in the New York Times article do not contribute to a belief that ADHD does not exist or cannot be accurately diagnosed. ADHD is a very real condition that scars a child’s educational and early social experiences. It can be accurately diagnosed and effectively treated.
David Shaffer is chair, DSM-5 Work Group on ADHD and Disruptive Behavior Disorders.