Russell A. Barkley

Behavioral inhibition, sustained attention, and executive functions: Constructing a unifying theory of ADHD.

Attention deficit hyperactivity disorder (ADHD) comprises a deficit in behavioral inhibition. A theoretical model is constructed that links inhibition to 4 executive neuropsychological functions that appear to depend on it for their effective execution: (a) working memory, (b) self-regulation of affect-motivation-arousal, (c) internalization of speech, and (d) reconstitution (behavioral analysis and synthesis). Extended to ADHD, the model predicts that ADHD should be associated with secondary impairments in these 4 executive abilities and the motor control they afford. The author reviews evidence for each of these domains of functioning and finds it to be strongest for deficits in behavioral inhibition, working memory, regulation of motivation, and motor control in those with ADHD. Although the model is promising as a potential theory of self-control and ADHD, far more research is required to evaluate its merits and the many predictions it makes about ADHD.

Attention-deficit hyperactivity disorder : a handbook for diagnosis and treatment

Part I: The Nature of ADHD. Barkley, History. Barkley, Primary Symptoms, Diagnostic Criteria, Prevalence, and Gender Differences. Barkley, Associated Cognitive, Developmental, and Health Problems. Barkley, Comorbid Disorders, Social and Family Adjustment, and Subtyping. Barkley, Etiologies. Barkley, ADHD in Adults: Developmental Course and Outcome of Children with ADHD, and ADHD in Clinic-referred Adults. Barkley, A Theory of ADHD. Part II: Assessment. Barkley, Edwards, Diagnostic Interview, Behavior Rating Scales, and the Medical Examination.Gordon, Barkley, Lovett, Tests and Observational Measures. Hathaway, Dooling-Litfin, Edwards, Integrating the Results of an Evaluation: Ten Clinical Cases. Murphy, Gordon, Assessment of Adults with ADHD. Part III: Treatment. Anastopoulos, Rhoads, Farley, Counseling and Training Parents. Cunningham, COPE: Large-group, Community-based, Family-centered Parent Training. Robin, Training Families with Adolescents with ADHD. Pfiffner, Barkley, DuPaul, Treatment of ADHD in School Settings. Cunningham, Cunningham, Student-mediated Conflict Resolution Programs. Connor, Stimulants. Spencer, Antidepressant and Specific Norepinephrine Reuptake Inhibitor Treatments. Connor, Other Medications. Smith, Barkley, Shapiro, Combined Child Therapies. Murphy, Psychological Counseling of Adults with ADHD. Prince, Wilens, Spencer, Biederman, Pharmacotherapy of ADHD in Adults.

The Adolescent Outcome of Hyperactive Children Diagnosed by Research Criteria: I. An 8-Year Prospective Follow-up Study

The psychiatric outcome is reported for a large sample of hyperactive children (N = 123), meeting research diagnostic criteria, and normal control children (N = 66) followed prospectively over an 8-year period into adolescence. Over 80% of the hyperactives were attention deficit hyperactivity disorder (ADHD) and 60% had either oppositional defiant disorder and/or conduct disorder at outcome. Rates of antisocial acts were considerably higher among hyperactives than normals, as were cigarette and marijuana use and negative academic outcomes. The presence of conduct disorder accounted for much though not all of these outcomes. Family status of hyperactives was much less stable over time than in the normal subjects. The use of research criteria for diagnosing children as hyperactive identifies a pattern of behavioral symptoms that is highly stable over time and associated with considerably greater risk for family disturbance and negative academic and social outcomes in adolescence than has been previously reported.

The persistence of attention-deficit/hyperactivity disorder into young adulthood as a function of reporting source and definition of disorder.

This study examined the persistence of attention-deficit/hyperactivity disorder (ADHD) into young adulthood using hyperactive (N = 147) and community control (N = 71) children evaluated at ages 19-25 years. ADHD was rare in both groups (5% vs. 0%) based on self-report but was substantially higher using parent reports (46% vs. 1.4%). Using a developmentally referenced criterion (+2 SD), prevalence remained low for self-reports (12% vs. 10%) but rose further for parent reports (66% vs. 8%). Parent reports were more strongly associated with major life activities than were self-reports. Recollections of childhood ADHD showed moderate correlations with actual parent ratings collected in childd hood, which suggests some validity for such recollections. The authors conclude that previous follow-up studies that relied on self-reports might have substantially underestimated the persistence of ADHD into adulthood.

Attention deficit hyperactivity disorder adults: Comorbidities and adaptive impairments

Attention deficit hyperactivity disorder (ADHD) is increasingly recognized as a legitimate adult diagnostic category. Yet the nature of and comorbidities and adaptive impairments associated with adult ADHD have received little scientific investigation. The present study, therefore, compared 172 adults diagnosed with ADHD with 30 adults referred to the same adult ADHD clinic who were not so diagnosed. The ADHD group showed a significantly greater prevalence of oppositional, conduct, and substance abuse disorders, and greater illegal substance use than control adults. Moreover, adults with ADHD displayed greater self-reported psychological maladjustment, more driving risks (speeding violations), and more frequent changes in employment. Significantly more ADHD adults had experienced a suspension of their driver license, had performed poorly, quit, or been fired from their job, and had a history of poorer educational performance and more frequent school disciplinary actions against them than adults without ADHD. Multiple marriages were more likely in the ADHD group as well. Contrary to previous studies, anxiety and mood disorders were not found to be more prevalent in the ADHD than in the control group. Results suggest that ADHD in adults is associated with relatively specific risks for disruptive behavior disorders, school and job performance problems, and driving risks.

Comprehensive evaluation of attention deficit disorder with and without hyperactivity as defined by research criteria.

Children with attention deficit disorder with hyperactivity (ADD+H; N = 48) were compared with those without hyperactivity (ADD-H; N = 42), as well as with learning disabled and control children, on an extensive battery of interviews, behavior ratings, tests, and direct observations. ADD+H children had more externalizing and internalizing symptoms by parent and teacher report, were more off task during vigilance testing, and had more substance abuse, ADD+H, and aggression among their relatives than did the other groups. ADD-H children were more day-dreamy and lethargic by teacher report, more impaired in perceptual-motor speed, and had more anxiety disorders among their relatives than did ADD+H children. Results indicate that these 2 types of ADD may be separate, distinct childhood disorders rather than subtypes of a common attention deficit.

Executive Functioning, Temporal Discounting, and Sense of Time in Adolescents with Attention Deficit Hyperactivity Disorder (ADHD) and Oppositional Defiant Disorder (ODD)

Clinic-referred teens (ages 12–19) with ADHD and ODD (N = 101) were compared to community control (CC) teens, equated for age and sex, (N = 39) on a variety of psychological tasks assessing executive functioning (EF), temporal reward discounting, and time estimation and reproduction. A factor analysis reduced the EF measures to three dimensions, representing CPT Inattention, Working Memory, and CPT Inhibition. Results indicated that the ADHD group had significantly more CPT Inattention than the CC group. No differences were found for Working Memory or CPT Inhibition. The ADHD group displayed significantly greater temporal discounting of delayed hypothetical monetary rewards relative to immediate ones and manifested more impaired time reproduction, but not time estimation, than did the CC group. Main effects for level of IQ were found only on the Working Memory factor and largely did not interact with the group factor otherwise. The group differences in CPT Inattention, temporal discounting, and time reproduction were not a function of level of comorbid oppositional defiant disorder, delinquency, or anxiety–depression. Results are reasonably consistent with past research on EF and sense of time in children with ADHD and extend these findings to the adolescent age group. Problems with working memory and CPT inhibition found in prior studies of children with ADHD, however, were not evident here, perhaps owing to age-related improvements or insufficient task difficulty.

Patterns and predictors of attention-deficit/ hyperactivity disorder persistence into adulthood : Results from the national comorbidity survey replication

BACKGROUND Despite growing interest in adult attention-deficit/hyperactivity disorder (ADHD), little is known about predictors of persistence of childhood cases into adulthood. METHODS A retrospective assessment of childhood ADHD, childhood risk factors, and a screen for adult ADHD were included in a sample of 3197 18-44 year old respondents in the National Comorbidity Survey Replication (NCS-R). Blinded adult ADHD clinical reappraisal interviews were administered to a sub-sample of respondents. Multiple imputation (MI) was used to estimate adult persistence of childhood ADHD. Logistic regression was used to study retrospectively reported childhood predictors of persistence. Potential predictors included socio-demographics, childhood ADHD severity, childhood adversity, traumatic life experiences, and comorbid DSM-IV child-adolescent disorders (anxiety, mood, impulse-control, and substance disorders). RESULTS Blinded clinical interviews classified 36.3% of respondents with retrospectively assessed childhood ADHD as meeting DSM-IV criteria for current ADHD. Childhood ADHD severity and childhood treatment significantly predicted persistence. Controlling for severity and excluding treatment, none of the other variables significantly predicted persistence even though they were significantly associated with childhood ADHD. CONCLUSIONS No modifiable risk factors were found for adult persistence of ADHD. Further research, ideally based on prospective general population samples, is needed to search for modifiable determinants of adult persistence of ADHD.

The Executive Functions and Self-Regulation: An Evolutionary Neuropsychological Perspective

Neuropsychology has customarily taken a molecular and myopic view of executive functioning, concentrating largely on those proximal processes of which it may be comprised. Although commendable as a starting point, such an approach can never answer the question, “Why executive functioning?” The present paper encourages neuropsychologists to contemplate the longer-term, functional nature of the executive functions (EFs), using an evolutionary perspective. For purely illustrative purposes, a previously developed model of the EFs is briefly presented and is then examined from an evolutionary perspective. That model views the EFs as forms of behavior-to-the-self that evolved from overt (public) to covert (private) responses as a means of self-regulation. That was necessary given the interpersonal competition that arises within this group-living species. The EFs serve to shift the control of behavior from the immediate context, social others, and the temporal now to self-regulation by internal representations regarding the hypothetical social future. The EFs seem to meet the requirements of a biological adaptation, being an improbable complex design for a purpose that exists universally in humans. Discovering the adaptive problems that the EFs evolved to solve offers an invaluable research agenda for neuropsychology lest that agenda be resolved first by other scientific disciplines. Some adaptive problems that the EFs may have evolved to solve are then considered, among them being social exchange (reciprocal altruism or selfish cooperation), imitation and vicarious learning as types of experiential theft, mimetic skill (private behavioral rehearsal) and gestural communication, and social self-defense against such theft and interpersonal manipulation. Although clearly speculative at the moment, these proposals demonstrate the merit of considering the larger adaptive problems that the EFs evolved to solve. Taking the evolutionary stance toward the EFs would achieve not only greater insight into their nature, but also into their assessment and into those larger adaptive capacities that may be diminished through injury or developmental impairment toward that system.

Young Adults With Attention Deficit Hyperactivity Disorder: Subtype Differences In Comorbidity, Educational, And Clinical History

The present study sought to examine subtype differences in comorbidity and in antisocial, educational, and treatment histories among young adults (ages 17–27) with attention deficit hyperactivity disorder (ADHD). Comparisons were made between ADHD Combined Type (ADHD-C;N = 60) and Predominantly Inattentive Type (ADHD-I;N = 36) relative to each other and to a community control group of 64 adults. Both ADHD groups had significantly less education, were less likely to have graduated from college, and were more likely to have received special educational placement in high school. Both groups also presented with a greater likelihood of dysthymia, alcohol dependence/abuse, cannabis dependence/abuse, and learning disorders, as well as greater psychological distress on all scales of the SCL-90-R than the control group. Both ADHD groups were more likely to have received psychiatric medication and other mental health services than control adults. In comparison with ADHD-I, adults with ADHD-C differed in only a few respects. The C-type adults were more likely to have oppositional defiant disorder, to experience interpersonal hostility and paranoia, to have attempted suicide, and to have been arrested than the ADHD-I adults. These results are generally consistent with previous studies of ADHD in children, extend these findings to adults with ADHD, and suggest that the greater impulsivity associated with the ADHD-C subtype may predispose toward greater antisocial behavior and its consequences than does ADHD-I type in adults.