Caryn L. Carlson

Gender Differences in ADHD: A Meta-Analysis and Critical Review

OBJECTIVE To quantitatively review and critically evaluate literature examining gender differences in attention-deficit hyperactivity disorder (ADHD). METHOD A meta-analysis of relevant research based on 18 studies meeting inclusion criteria was performed. Domains evaluated included primary symptomatology, intellectual and academic functioning, comorbid behavior problems, social behavior, and family variables. RESULTS Gender differences were not found in impulsivity, academic performance, social functioning fine motor skills, parental education, or parental depression. However, compared with ADHD boys, ADHD girls displayed greater intellectual impairment, lower levels of hyperactivity, and lower rates of other externalizing behaviors; it was not possible to evaluate the extent to which referral bias affected these findings. Some gender differences were clearly mediated by the effects of referral source; among children with ADHD identified from nonreferred populations, girls with ADHD displayed lower levels of inattention, internalizing behavior, and peer aggression than boys with ADHD, while girls and boys with ADHD identified from clinic-referred samples displayed similar levels of impairment on these variables. CONCLUSIONS The need for future research examining gender differences in ADHD is strongly indicated, with attention to methodological limitations of the current literature, including the potential confounding effects of referral bias, comorbidity, developmental patterns, diagnostic procedures, and rater source.

Validity of DSM-IV attention deficit/hyperactivity disorder symptom dimensions and subtypes.

Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria for attention deficit/hyperactivity disorder (ADHD) specify two dimensions of inattention and hyperactivity-impulsivity symptoms that are used to define three nominal subtypes: predominantly hyperactive-impulsive type (ADHD-H), predominantly inattentive type (ADHD-I), and combined type (ADHD-C). To aid decision making for DSM-5 and other future diagnostic systems, a comprehensive literature review and meta-analysis of 546 studies was completed to evaluate the validity of the DSM-IV model of ADHD. Results indicated that DSM-IV criteria identify individuals with significant and persistent impairment in social, academic, occupational, and adaptive functioning when intelligence, demographic factors, and concurrent psychopathology are controlled. Available data overwhelmingly support the concurrent, predictive, and discriminant validity of the distinction between inattention and hyperactivity-impulsivity symptoms, and indicate that nearly all differences among the nominal subtypes are consistent with the relative levels of inattention and hyperactivity-impulsivity symptoms that define the subtypes. In contrast, the DSM-IV subtype model is compromised by weak evidence for the validity of ADHD-H after first grade, minimal support for the distinction between ADHD-I and ADHD-C in studies of etiological influences, academic and cognitive functioning, and treatment response, and the marked longitudinal instability of all three subtypes. Overall, we conclude that the DSM-IV ADHD subtypes provide a convenient clinical shorthand to describe the functional and behavioral correlates of current levels of inattention and hyperactivity-impulsivity symptoms, but do not identify discrete subgroups with sufficient long-term stability to justify the classification of distinct forms of the disorder. Empirical support is stronger for an alternative model that would replace the subtypes with dimensional modifiers that reflect the number of inattention and hyperactivity-impulsivity symptoms at the time of assessment. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

Behavioral Characteristics of DSM-IV ADHD Subtypes in a School-Based Population

From an ethnically diverse sample of 2,744 school children, 221 attention deficit hyperactivity disorder (ADHD) [123 (4.5%) predominantly inattentive (IA), 47 (1.7%) predominantly hyperactive/impulsive (HI), and 51 (1.9%) combined type (C)] were identified using teacher ratings on a Diagnostic and Statistical Manual of Mental Disorders (4th ed.) (DSM-IV) symptom checklist. Subjects were compared to 221 controls on teacher ratings of behavioral, academic, and social functioning. The results revealed relatively independent areas of impairment for each diagnostic group. The IA children were impaired in all areas, but were rated as displaying more appropriate behavior and fewer externalizing problems than HI or C children. The HI group displayed externalizing and social problems, but was rated as no different than controls in learning or internalizing problems. The C group demonstrated severe and pervasive difficulties across domains. These findings support the validity of the DSM-IV ADHD subtypes; all ADHD groups demonstrated impairment relative to controls, but show different patterns of behavioral characteristics.

Attention deficit disorder with and without hyperactivity: comparison of behavioral characteristics of clinic-referred children.

Using a reliable assessment procedure, 41 clinic outpatients, 6–13 years of age, were given a diagnosis of Attention Deficit Disorder with Hyperactivity (ADD/H), and 22 outpatients were diagnosed as having Attention Deficit Disorder without Hyperactivity (ADD/WO). Comparisons of measures involved in the diagnostic process showed that the ADD/H children were rated by teachers as being more impulsive. More importantly, comparisons of measures not used in the diagnoses showed that children with ADD/H were more likely to display a severe pattern of aggressive conduct disorder in spite of being younger at the time of assessment. In contrast, the ADD/WO group displayed a more sluggish cognitive tempo, was more likely to receive a codiagnosis of an anxiety or affective disorder, and tended to be rated as more anxious. The results were found not to be explainable by differences in age, intelligence, or socioeconomic status. These findings demonstrate that ADD/WO can be reliably diagnosed in a clinic sample and suggest that ADD/H and ADD/WO differ in important ways.

Separate and combined effects of methylphenidate and behavior modification on boys with attention deficit-hyperactivity disorder in the classroom

This study evaluated the separate and combined effects of behavior modification and 2 doses of methylphenidate (MPH; 0.3 and 0.6 mg/kg) compared with baseline (no behavior modification and a placebo) on the classroom behavior and academic performance of 31 ADHD (attention deficit-hyperactivity disorder) boys attending a summer treatment program. Results revealed significant effects of both interventions, with the mean effect size of medication being more than twice as great as that of behavior modification. Relatively small incremental value was gained by the higher dose of medication or the addition of behavior modification, compared with the effects of the low dose of MPH. In contrast, the addition of either dose of MPH resulted in improvement beyond the effects of behavior modification alone. These group effects reflected those obtained in analyses of individual differences. Furthermore, comparisons of individual responsiveness showed that boys who responded to one treatment also responded to the other.

Single and Combined Effects of Methylphenidate and Behavior Therapy on the Classroom Performance of Children with Attention-Deficit Hyperactivity Disorder

Twenty-four boys with attention deficit-hyperactivity disorder (ADHD) participating in an intensive summer treatment program each received b.i.d. placebo and two doses of methylphenidate (MPH, 0.3 mg/kg and 0.6 mg/kg) crossed with two classroom settings: a behavior modification classroom including a token economy system, time out and daily home report card, and a “regular” classroom setting not using these procedures. Dependent variables included classroom observations of on-task and disruptive behavior, academic work completion and accuracy, and daily self-ratings of performance. Both MPH and behavior modification alone significantly improved childrens classroom behavior, but only MPH improved childrens academic productivity and accuracy. Singly, behavior therapy and 0.3 mg/kg PMH produced roughly equivalent improvements in classroom behavior. Further, the combination of behavior therapy and 0.3 mg/kg MPH resulted in maximal behavioral improvements, which were nearly identical to those obtained with 0.6 mg/kg MPH alone.

Validity of the Diagnostic Category of Attention Deficit Disorder Without Hyperactivity A Review of the Literature

The validity of the diagnostic category of Attention Deficit Disorder Without Hyperactivity (ADD/WO) has been the subject of debate since it was first introduced in DSM-III. The differentiation of two syndromes of ADD is supported by factor analytic studies that indicate two dimensions of maladjustment: (1) inattention and disorganization, and (2) motor hyperactivity and impulsive responding. Cluster analyses of these two dimensions have yielded two profiles of deviance that correspond to the DSM-III subtypes. Furthermore, clinic-referred children who meet DSM-III criteria for ADD/WO have been shown to exhibit less serious conduct problems, are less impulsive, are more likely to be characterized as sluggish and drowsy, are less rejected by peers but more socially withdrawn, and are more likely to exhibit depressed mood and symptoms of anxiety disorder than children with Attention Deficit Disorder with Hyperactivity (ADD/H).

The Texas Children's Medication Algorithm Project : Report of the Texas Consensus Conference Panel on Medication Treatment of Childhood Attention-Deficit/Hyperactivity Disorder. Part II : Tactics

OBJECTIVES Expert consensus methodology was used to develop a medication treatment algorithm for attention-deficit/hyperactivity disorder (ADHD). The algorithm broadly outlined the choice of medication for ADHD and some of its most common comorbid conditions. Specific tactical recommendations were developed with regard to medication dosage, assessment of drug response, management of side effects, and long-term medication management. METHOD The consensus conference of academic clinicians and researchers, practicing clinicians, administrators, consumers, and families developed evidence-based tactics for the pharmacotherapy of childhood ADHD and its common comorbid disorders. The panel discussed specifics of treatment of ADHD and its comorbid conditions with stimulants, antidepressants, mood stabilizers, alpha-agonists, and (when appropriate) antipsychotics. RESULTS Specific tactics for the use of each of the above agents are outlined. The tactics are designed to be practical for implementation in the public mental health sector, but they may have utility in many practice settings, including the private practice environment. CONCLUSIONS Tactics for psychopharmacological management of ADHD can be developed with consensus.

Direct assessment of the cognitive correlates of attention deficit disorders with and without hyperactivity

The cognitive functioning of children identified as attention deficit disorder with hyperactivity (ADD/H) was compared to that of children identified as attention deficit disorder without hyperactivity (ADD/WO). Based on information on symptoms supplied by teachers, 20 ADD/H and 15 ADD/ WO children were selected according to DSM-III criteria from a large elementaryschool learning disabilities and behavior disorders population. For comparison purposes, 16 normal children from regular classrooms were also selected. Children from all three groups were evaluated with a battery of cognitive tests. Intelligence test scores differentiated the two ADD groups, with the ADD/H children obtaining significantly lower Full Scale IQ scores than both ADD/WO and control children. In addition, ADD/H children obtained significantly lower Verbal IQ scores than ADD/WO children. Both ADD groups performed more poorly than controls on Spelling and Reading Achievement, and the ADD/WO group performed more poorly on Math Achievement. The two ADD groups took longer to complete six Stroop and rapid naming tasks than the control groups but did not differ among themselves. The ADD/WO group made more errors on a visual matching task than the controls, but neither ADD group differed from controls on the accuracy of the Stroop tasks, rapid naming tasks, measures of receptive and expressive language, visual-motor integration, or sustained visual attention. The differences between the two ADD groups were fewer than expected on the basis of previous research and are more global than specific.

Responsiveness of children with attention deficit-hyperactivity disorder to reward and response cost: Differential impact on performance and motivation

Using a within-subject design and both high- and low-interest tasks, this study examined the effects of reward (R), response cost (RC), and no contingency (NR) on performance and motivation of 22 children with attention deficit-hyperactivity disorder (ADHD) and 22 controls. Dependent variables included performance measures, self-rated performance and motivation, and a new measure of behavioral motivation based on a 2-min postcontingency task. Both contingencies benefited some aspects of the performance of ADHD children; relative to R, RC showed stronger effects but at the expense of decreased self-rated motivation on the low-interest task. The performance of controls did not differ across tasks, whereas ADHD children performed relatively better on the high-interest task. Neither contingency decreased motivation measures relative to NR for either group. For ADHD children, motivational effects appeared to be influenced by self-perceptions of performance.