Diagnosis of ADHD in Adults: What Is the Appropriate DSM-5 Symptom Threshold for Hyperactivity-Impulsivity?

Objective: To empirically identify the appropriate symptom threshold for hyperactivity-impulsivity for diagnosis of ADHD in adults. Method: Participants were 88 adults (M [SD] age = 41.69 [11.78] years, 66% female, 16% minority) meeting formal DSM-IV criteria for ADHD combined or predominantly inattentive subtypes based on a structured diagnostic interview keyed to DSM-IV (Conners' Adult ADHD Diagnostic Interview for DSM-IV [CAADID]). All participants also completed the Conners' Adult ADHD Rating Scale (CAARS), which was normed on the general adult population and includes subscales for DSM-IV inattentive and DSM-IV hyperactive-impulsive symptoms. A T-score threshold of 65 (at least 1.5 SD above population mean) on the CAARS DSM-IV hyperactive-impulsive dimension was used to identify participants with empirically elevated symptom severity. Results: Of 88 participating adults, 48 (55%) had a T-score of at least 65 (1.5 SD) on the CAARS DSM-IV Hyperactive-Impulsive scale. Of these, only 25 (52%) met the DSM-IV cutoff of six hyperactive-impulsive symptoms on the CAADID. Thus, approximately half of those who reported empirically elevated hyperactive-impulsive complaints on the CAARS did not concurrently meet the six-symptom DSM-IV cutoff on the CAADID. An alternative cutoff of four hyperactive-impulsive symptoms on the CAADID captured 39 (81%) cases identified by the CAARS. Conclusion: In adults, mandating at least six hyperactive-impulsive symptoms excludes a significant percentage (almost half) of adults who are at least 1.5 SD above the population mean on a dimensional measure of hyperactivity-impulsivity. These data provide a compelling basis for lowering the symptom threshold of hyperactivity-impulsivity for adults in the DSM-5.     

The Science and Ethics of Placebo in Pediatric Psychopharmacology

Pediatric psychopharmacology is a relatively new science. Although the use of psychotropic medications in children has risen in the past decade, there are few standard treatments for serious psychiatric or developmental disorders of childhood. The relative absence of standard treatments is further complicated by the fact that many of the agents used in pediatric psychopharmacology have been adapted from other fields. Therefore, investigators have a responsibility to make incremental progress from concept through pilot studies and large-scale, multisite efficacy and safety trials. Thus, although there is a pressing need to conduct medication trials that can guide clinical practice, there are scientific and ethical considerations to bear in mind when designing clinical trials in pediatric psychopharmacology. This article reviews essential ethical and scientific issues that are relevant to designing clinical trials in children with psychiatric and developmental disorders. Using examples from recently published literature, the article describes the challenges and pitfalls of various clinical trial study designs. The application of sound ethical and scientific principles is necessary to ensure that clinical trials are properly conducted and to guard against ambiguous results that can not guide practice.     

The Ecological Validity of Delay Aversion and Response Inhibition as Measures of Impulsivity in AD/HD: A Supplement to the NIMH Multimodal Treatment Study of AD/HD

Impulsivity is a primary symptom of the combined type of Attention Deficit/Hyperactivity Disorder (AD/HD). The Stop Signal Paradigm is premised upon a primary deficit in inhibitory control in AD/HD, whereas the Delay Aversion Hypothesis, by contrast, conceptualizes impulsivity in AD/HD, not as an inability to inhibit a response, but rather as a choice to avoid delay. This study compared the ecological validity of the Stop Signal Task (SST) and Choice-Delay Task (C-DT) measure of delay aversion, with respect to their relative utility in discriminating AD/HD children from normal control participants, and their correlations with classroom observations and with ratings of impulsivity and other core AD/HD symptoms on the Conners and SNAP-IV checklists. The tasks exhibited modest discriminant validity when used individually and excellent discriminant validity when used in combination. The C-DT correlated with teacher ratings of impulsivity, hyperactivity, and conduct problems, and with observations of gross motor activity, physical aggression, and an AD/HD composite score. The SST correlated with the observations only. These results suggest that delay aversion is associated with a broad range of AD/HD characteristics whereas inhibitory failure seems to tap a more discrete dimension of executive control     

The predominantly inattentive subtype of attention-deficit/hyperactivity disorder

The predominantly inattentive (IN) subtype of attention-deficit/hyperactivity disorder (ADHD) is a recently defined condition that is often overlooked by professionals and is still not completely understood. Characterized by symptoms of inattentiveness, such as distractibility, failure to complete work, forgetfulness, and disorganization, the IN subtype differs from the more commonly recognized combined (CB) subtype of ADHD in that symptoms of hyperactivity and impulsivity are absent or minimal. Large-scale epidemiologic studies suggest that the IN subtype is at least as prevalent as the CB subtype, and is at least as likely to be associated with academic and/or social impairment. Diagnosis of the IN subtype, however, may be more challenging because in addition to inattentiveness, other symptoms, including learning problems, depression, and anxiety, may also present without externalizing behaviors. Several studies have shown that compared with the CB subtype, the IN subtype has a later age of onset and referral, a relatively larger proportion of affected females, and is much less likely to be associated with symptoms of oppositional defiant disorder or conduct disorder. Research is currently under way to examine the cognitive characteristics of the IN subtype and its genetic and neurobiologic underpinnings, as well as to evaluate the effectiveness of pharmacotherapy and other treatments.     

Neurocognitive Functioning in AD/HD,Predominantly Inattentive and Combined Subtypes

The Predominantly Inattentive (PI) and Combined (CB) subtypes of AD/HD differ in cognitive tempo, age of onset, gender ratio, and comorbidity, yet a differentiating endophenotype has not been identified. The aim of this study was to test rigorously diagnosed PI, CB, and typical children on measures selected for their potential to reveal hypothesized differences between the subtypes in specific neurocognitive systems (anterior vs. posterior attentional systems) and processes (arousal vs. activation). Thirty-four CB and 26 PI children meeting full DSM-IV criteria for subtype both in school and at home, without confounding reading disability or emotional disorder, were enrolled along with 20 typically developing children. Neurocognitive functions measured included attention, inhibitory control, working memory, learning, and executive functions. Tasks included the Stroop, Wisconsin Card Sorting Test, Continuous Performance Test (CPT). Buschke Selective Reminding Test, ad the Tower of London (TOL), as well as instruments developed by Posner and Sternberg, and tasks assessing the impact on reaction time of [corrected] varying preparatory intervals and stimulus/response complexity. After co-varying for IQ, subtypes differed primarily on measures of impulsivity during tests of vigilance (CPT) and executive function (TOL), with the CB group showing greater impulsivity than both other groups. In addition, the PI group showed worse performance than CB and control groups on the WISC-III Processing Speed Index. Whether analyzed with or without an IQ co-variate, there was no support in the data for hypothesized differences between subtypes in functioning of the anterior vs. posterior attentional systems, nor in involvement of arousal vs. activation processes. The results indicate that the PI and CB subtypes are best differentiated by ratings, observations and tests of cognitive tempo and behavioral impulsivity. Neuropsychological methods have yet to identify critical neuropsychological [corrected] substrates of these differences.