Jeffrey M. Halperin

Revisiting the Role of the Prefrontal Cortex in the Pathophysiology of Attention-Deficit/Hyperactivity Disorder.

Most neural models for the pathophysiology of attention-deficit/hyperactivity disorder (ADHD) have centered on the prefrontal cortex and its interconnections with the striatum and other subcortical structures. However, research only partially supports these models, and they do not correspond with the development of the prefrontal cortex and its interrelated neurocircuitry. The neural and functional development of the prefrontal cortex more closely parallels recovery from ADHD as indicated by the developmental remission of symptomatology. The authors hypothesize that ADHD is due to noncortical dysfunction that manifests early in ontogeny, remains static throughout the lifetime, and is not associated with the remission of symptomatology. Data supporting this neurodevelopmental model of prefrontal cortex function in ADHD are reviewed. Research and treatment implications are discussed.

Parent–Teacher Concordance for DSM-IV Attention-Deficit/Hyperactivity Disorder in a Clinic-Referred Sample

OBJECTIVE To examine concordance between parent and teacher reports of DSM-IV attention-deficit/hyperactivity disorder (ADHD) and its symptoms. METHOD Parents and teachers of 74 clinically referred children were interviewed using the ADHD module of the Diagnostic Interview Schedule for Children. Parent-teacher agreement for the diagnosis of ADHD and its subtypes, as defined in DSM-IV, as well as parent-teacher concordance of in-school ADHD symptoms, was examined. RESULTS Agreement between parents and teachers was found to be relatively poor, with virtually no agreement for individual ADHD subtypes. Diagnoses based on either parent or teacher report frequently yielded a diagnosis of either inattentive or hyperactive-impulsive subtype of ADHD. However, when cross-informant data were used to form diagnoses, these subtypes became relatively rare, with most cases meeting criteria for ADHD combined type. In addition, parent reports of in-school behavior were more highly correlated with their own reports of their childs behavior at home than with teacher reports of their childs behavior in school. CONCLUSIONS These data suggest that the diagnosis of ADHD inattentive or hyperactive-impulsive subtype based on data from a single informant may be of questionable validity, and they point to the importance of using multiple informants when diagnosing this disorder in clinically referred samples.

Neuropsychological outcome in adolescents/young adults with childhood ADHD: profiles of persisters, remitters and controls.

BACKGROUND This study examined neuropsychological functioning in a longitudinal sample of adolescents/young adults with attention deficit/hyperactivity disorder (ADHD) and controls as a function of the persistence of ADHD. We hypothesized that measures of executive processes would parallel adolescent clinical status, with ADHD-persisters, but not remitters, differing significantly from controls. In contrast, persisters and remitters were hypothesized to perform similarly, and different from controls, on tasks requiring less effortful processing. METHODS Ninety-eight participants diagnosed with ADHD in childhood were reevaluated approximately 10 years later. Eighty-five never-ADHD controls similar in age, IQ, and sex distribution served as a comparison group. Participants were administered a psychiatric interview and neuropsychological test battery. RESULTS Those with childhood ADHD demonstrated broad neuropsychological deficits relative to controls. When the group with childhood ADHD was subdivided based on adolescent ADHD status, compared to controls, both persisters and remitters showed deficient perceptual sensitivity and response variability, and increased ankle movements recorded by a solid-state actigraph. Only persisters differed from controls on several measures of more effortful executive processes. CONCLUSIONS Findings provide preliminary support to the hypothesis that ADHD is associated with early-appearing and enduring subcortical dysfunction, while recovery over the course of development is associated with improvements in executive control functions.

Differential Assessment of Attention and Impulsivity in Children

Abstract A sample of 72 unselected school children was administered the continuous performance test. Of the four types of commission errors that were identified, two occurred at significantly different reaction times than correct responses. One was characterized by fast reaction times and appears to reflect impulsive or rapid responding, while the other occurred at slow reaction times and appears to be caused by inattention. Correlations with teacher ratings of behavior further support the notion that different types of commission errors assess different underlying psychological functions.

Comprehensive assessment of childhood Attention-Deficit Hyperactivity Disorder in the context of a multisite, multimodal clinical trial

As the largest randomized clinical trial conducted by the National Institute of Mental Health, the Multimodal Treatment Study of Children with ADHD (MTA) will yield data on a diverse sample of 576 7.0- to 9.9-year-old children with attention-deficit hyperactivity disorder (ADHD), Combined type, regarding the relative and combined effectiveness of psychosocial and pharmacologic interventions. After delineating key challenges posed by such a multi-site investigation, we describe the MTAs multiple-gating procedures for recruitment, screening, and diagnosis of a diverse sample. We then discuss the cross-domain assessment battery for tracking the sample before, during, and after 14 months of active intervention. Throughout, we emphasize the guiding principles that shaped pertinent decision making. Highlighted are issues of psychometric adequacy; dimensional vs. categorical measurement; multi-method, multi-agent, and multi-domain coverage; plotting of individual trajectories of development and change; respondent bias and burden; appraisal of treatment processes as well as outcomes; and con struction of composite indices.

The Influences of Environmental Enrichment, Cognitive Enhancement, and Physical Exercise on Brain Development: Can we Alter the Developmental Trajectory of ADHD?

Attention-deficit/Hyperactivity Disorder (ADHD) is characterized by a pervasive pattern of developmentally inappropriate inattentive, impulsive and hyperactive behaviors that typically begin during the preschool years and often persist into adulthood. The most effective and widely used treatments for ADHD are medication and behavior modification. These empirically-supported interventions are generally successful in reducing ADHD symptoms, but treatment effects are rarely maintained beyond the active intervention. Because ADHD is now generally thought of as a chronic disorder that is often present well into adolescence and early adulthood, the need for continued treatment throughout the lifetime is both costly and problematic for a number of logistical reasons. Therefore, it would be highly beneficial if treatments would have lasting effects that remain after the intervention is terminated. This review examines the burgeoning literature on the underlying neural determinants of ADHD along with research demonstrating powerful influences of environmental factors on brain development and functioning. Based upon these largely distinct scientific literatures, we propose an approach that employs directed play and physical exercise to promote brain growth which, in turn, could lead to the development of potentially more enduring treatments for the disorder.

Specificity of Inattention, Impulsivity, and Hyperactivity to the Diagnosis of Attention-deficit Hyperactivity Disorder

Children with attention-deficit hyperactivity disorder (ADHD) were compared with non-ADHD psychiatric patients and normal controls on objective measures of inattention, impulsivity, and hyperactivity to determine the specificity of these symptoms to ADHD. Inattention and impulsivity were assessed using a continuous performance test, and activity was measured using solid state actigraphs. Both patient groups were inattentive relative to normals, but were indistinguishable from each other. However, the ADHD group was more active than both non-ADHD patients and normals, who did not differ from each other. These data suggest that inattention may be a nonspecific symptom of child psychiatric disorder. However, ADHD may be uniquely characterized by overactivity.

Methylphenidate response in aggressive and nonaggressive ADHD children: distinctions on laboratory measures of symptoms.

Response to a single, 5-mg dose of methylphenidate was compared in aggressive and nonaggressive attention-deficit hyperactivity disorder (ADHD) children using objective measures of inattention, impulsivity, and activity level. After medication, both ADHD groups had a significant decrease in inattention, whereas impulsivity remained unchanged. Activity level decreased only in the nonaggressive ADHD group. Unmedicated normal controls showed no change on any measure. These results support the hypothesis that aggressive and nonaggressive ADHD children have somewhat different underlying determinants for some of their symptoms. In addition, they suggest that inattention, impulsivity, and overactivity may be mediated by partially distinct neural mechanisms.

Subtype analysis of commission errors on the continuous performance test in children

Most investigators agree that errors of omission on the continuous performance test (CPT) reflect some aspect of inattention; however, there is less agreement regarding the significance of commission errors. Although many investigators believe that commission errors reflect impulsivity, others are skeptical. We proposed that CPT commission errors do not comprise a unitary measure and that subtypes can be distinguished based on the specific nature of the errors. Our investigation identified four subtypes of commission errors and found that reaction times associated with them differed significantly, in agreement with a priori predictions, suggesting that they reflect differential underlying psychological processes. Although certain commission errors appear to reflect impulsivity, the data suggest that others do not.

Developmental analysis of three aspects of information processing: Sustained attention, selective attention, and response organization

The development of cognitive abilities associated with Lunas (1973) three functional units of the brain was investigated in a sample of 62 children, ages 7 to 11 years, and 16 adults, ages 21 to 48 years. Selective attention, associated primarily with Lurias sensory‐input unit, showed no demonstrable development within the age ranges studied. However, sustained attention, presumably mediated through Lurias arousal unit and its ascending fibers to the cortex, as well as response organization, associated with Lunas organization‐and‐ planning unit, did reflect differential development Capacity for sustained attention showed no appreciable development between 7 and 11 years of age, but there was significant growth in this ability between age 11 and adulthood. Response organization, on the other hand, was found to develop most rapidly between 7 and 11 years of age. These findings are partially consistent with Lurias model of neurodevelopment as well as with research investigating the functional and physio...