Neurocognitive functioning in adults with attention-deficit/hyperactivity disorder

The performance of nine adults with attention-deficit/hyperactivity disorder (ADHD) was compared with the performance of 23 normal controls on computerized measures of target orientation, sustained attention, encoding speed, and motor output/response organization to determine the nature of the neurocognitive deficits of adults with ADHD. While the groups' performances on measures of sustained attention and encoding speed did not differ, significant group differences were seen on a task that targeted motor output/response organization. These data suggest that the neurocognitive difficulties of ADHD adults are not related to a primary deficit in sustained attentional functioning. Rather, the deficient information processing in ADHD adults is related to difficulties with motor output/response organization.     

Impairment of executive functions in boys with attention deficit/hyperactivity disorder.

The main aim of the present study is to compare the efficiency of executive control processes in 24 boys with attention deficit/hyperactivity disorder (ADHD) and 58 normal controls of similar age (between 8 and 11 years). Three reaction time (RT) paradigms were utilized: a dual task that requires coordination of two tasks responses, a shift task that makes it necessary to disengage attention from one task and engage into another one, and a stimulus-response spatial compatibility task that requires participants to inhibit a prepotent response. Another purpose of the study is to examine whether Barkley's (1997) executive dysfunction or Sergeant et al.'s (1999) resource allocation/arousal model best account for the behavioral deficits associated with ADHD. Examination of raw RT data showed significantly poorer performance in ADHD children with respect to age-matched controls on both the higher-level cognitive functions of executive control and on lower-level abilities (e.g., speed of processing) of all tasks of this study. However, using proportional transformations of raw RT data, we could demonstrate that, in addition to differences in processing speed, also executive control processes were significantly impaired in children with ADHD.     

Cross-lateralisation in children with attention-deficit/hyperactivity disorder and motor skill performance

Cross-lateralisation and increased motor difficulties have been reported in children with attention-deficit/hyperactivity disorder (ADHD). Nevertheless, the question of how crossed (i.e. mixed preference) or uncrossed (i.e. same side preference) lateralisation impacts motor performance in children with ADHD has yet to be examined. In this study, previously validated observational measures of hand and foot preference were used to identify right-handed children with ADHD who display cross- (n = 29) and uncross-lateralisation (n = 31). An uncross-lateralised typically developing (TD) group (n = 32) was also identified, and included as a control. Motor performance was assessed with seven valid and reliable fine and gross motor tasks performed with both preferred and non-preferred limbs. Group, task and sex-related effects were examined. Findings revealed that male (but not female) cross-lateralised children with ADHD performed significantly worse, respectively, in two of the fine motor tasks (spiral tracing [p < .01], and dot filling [p < .05]). Results suggest that cross-lateralised hand and foot preference may affect complex motor skills in male children with ADHD. Furthermore, characteristics of ADHD may manifest differently in male and female children. Findings highlight the importance of considering both hand and foot preference when targeting motor interventions for children with ADHD.     

A psychophysical measure of attention deficit in children with attention-deficit/hyperactivity disorder

The authors explored the temporal mechanism of attention deficit in children with attention-deficit/hyperactivity disorder (ADHD). In rapid serial visual presentation tasks in which two targets (T-sub-1 and T-sub-2) were presented in close temporal proximity among distractors, participants tried to identify T-sub-1 and detect T-sub-2 in one (dual-task) experiment and only to detect T-sub-2 in a second control (single-task) experiment. The sensitivity of T-sub-2 detection was analyzed using signal detection theory. The attentional blink--the impairment in T-sub-2 detection following the identification of T-sub-1--was increased in magnitude and protracted in the patients. Moreover, some ADHD children appeared to have a blink largely normal in magnitude but temporally displaced toward a later time. The authors hypothesize that a slower closing of the attention gate may mediate this specific attention impairment in ADHD children.     

Differences in memory functioning between children with attention-deficit/hyperactivity disorder and/or focal epilepsy

Prior research has shown that attention-deficit/hyperactivity disorder (ADHD) and epilepsy are frequently comorbid and that both disorders are associated with various attention and memory problems. Nonetheless, limited research has been conducted comparing the two disorders in one sample to determine unique versus shared deficits. Hence, we investigated differences in working memory (WM) and short-term and delayed recall between children with ADHD, focal epilepsy of mixed foci, comorbid ADHD/epilepsy and controls. Participants were compared on the Core subtests and the Picture Locations subtest of the Children’s Memory Scale (CMS). Results indicated that children with ADHD displayed intact verbal WM and long-term memory (LTM), as well as intact performance on most aspects of short-term memory (STM). They performed worse than controls on Numbers Forward and Picture Locations, suggesting problems with focused attention and simple span for visual-spatial material. Conversely, children with epilepsy displayed poor focused attention and STM regardless of the modality assessed, which affected encoding into LTM. The only loss over time was found for passages (Stories). WM was intact. Children with comorbid ADHD/epilepsy displayed focused attention and STM/LTM problems consistent with both disorders, having the lowest scores across the four groups. Hence, focused attention and visual-spatial span appear to be affected in both disorders, whereas additional STM/encoding problems are specific to epilepsy. Children with comorbid ADHD/epilepsy have deficits consistent with both disorders, with slight additive effects. This study suggests that attention and memory testing should be a regular part of the evaluation of children with epilepsy and ADHD.     

Separating automatic and intentional inhibitory mechanisms of attention in adults with attention-deficit/hyperactivity disorder

Researchers in the cognitive sciences recognize a fundamental distinction between automatic and intentional mechanisms of inhibitory control. The use of eye-tracking tasks to assess selective attention has led to a better understanding of this distinction in specific populations, such as children with attention-deficit/hyperactivity disorder (ADHD). This study examined automatic and intentional inhibitory control mechanisms in adults with ADHD using a saccadic interference task and a delayed ocular response task. Thirty adults with ADHD were evaluated against 27 comparison adults on measures of inhibitory control. The delayed ocular response task showed that adults with ADHD were less able than comparison adults to inhibit a reflexive saccade toward the sudden appearance of a stimulus in the periphery. However, saccadic interference task performance showed that the ADHD group did not differ significantly from the comparison group on a measure of automatic inhibitory control. These findings suggest a dissociation between automatic and intentional inhibitory deficits in adults with ADHD.     

Frontal lobe functioning in adolescents with attention deficit hyperactivity disorder

A prominent hypothesis regarding the etiology of attention deficit hyperactivity disorder (ADHD) is that its presence and magnitude reflect frontal lobe dysfunction. Past tests of this hypothesis have been inconsistent. The present study examined frontal lobe functioning in adolescents with ADHD. A sample of 10 ADHD adolescents and 10 controls between the ages of 12 and 17 served as participants for the study. The control group was matched on age (within six months) and gender. This study aided in clarifying past contradictory studies by using clearly defined criteria to determine ADHD, a representative age range of participants, carefully selected tests, and a control task. The two measures that were administered to assess frontal lobe functioning were the Wisconsin Card Sorting Test and the Stroop Color and Word Test. The Purdue Pegboard was used as a control measure that did not assess frontal lobe functioning. The findings indicate that the ADHD group performed significantly worse on the following: color score, color/word score, and interference score of the Stroop Color and Word Test; percent of perseverative responses, percent of perseverative errors, and number of completed categories of the Wisconsin Card Sorting Test. No differences were found on the Purdue Pegboard task.     

School-based intervention for adolescents with attention-deficit/hyperactivity disorder: Effects on academic functioning

Multi-component training interventions such as the Challenging Horizons Program (CHP) improve organization skills and academic functioning of middle school students with attention-deficit/hyperactivity disorder (ADHD); however, few studies have investigated treatment for high school students. We explored the extent to which CHP adapted for high school would improve proximal (e.g., organization skills, homework performance) and distal (e.g., report card grades) academic outcomes through 6-month follow-up relative to a community care (CC) condition. Participants included 186 adolescents who were randomly assigned to CHP (n = 92; 80% male; M age = 15.0; SD = 0.8) or CC (n = 94; 78% male; M age = 15.1; SD = 0.9) with CHP delivered over one school year. Parent, teacher, and self-report ratings of organization skills and academic performance, report card grades, and achievement tests were collected across multiple occasions. Intent-to-treat analyses using hierarchical linear modeling revealed significant improvements of small to medium magnitude (d range = 0.32 to 0.58) for parent-rated organization skills, homework performance, and academic functioning at 6-month follow-up. CHP effect on grades was small, but associated with a less steep decline than that found for CC. No statistically significant effects on teacher or self-report ratings were obtained. CHP appears efficacious for ameliorating organization skills and homework performance deficits exhibited by high school students with ADHD and can protect against decline in report card grades experienced by these students. CHP may require supplementation with academic skills instruction for some students and may need implementation beyond one school year to produce durable effects.     

Neuropsychological functioning in nonreferred siblings of children with attention deficit/hyperactivity disorder

The goal of this study was to assess neuropsychological functioning in nonreferred siblings of children with attention deficit/hyperactivity disorder (ADHD). Participants were 156 siblings of ADHD probands with (N = 40) and without (N = 116) ADHD (according to criteria of the Diagnostic and Statistical Manual of Mental Disorders (3rd edition, revised; American Psychiatric Association, 1987) and 118 siblings of non-ADHD normal controls of similar age, IQ, and grade level. Information on attention, executive, and memory functions was obtained in a standardized manner without knowledge of clinical status. Compared with siblings of controls, siblings with ADHD were significantly impaired on the Stroop test and on verbal learning and memory. In contrast, siblings without ADHD were similar to controls on virtually all measures. These data suggest that some executive, attention, and verbal learning deficits are found in nonreferred individuals with ADHD but that neuropsychological deficits are unlikely to constitute an endophenotype to ADHD.     

Non-stimulant treatment of attention-deficit/hyperactivity disorder

Stimulants are a highly efficacious and safe treatment for attention-deficit/hyperactivity disorder (ADHD), with 75% to 90% of patients responding well if two different stimulants (amphetamine and methylphenidate) are used. Nonetheless, a subset of ADHD patients will either fail to respond to stimulants or have side effects that preclude their use (tics, severe loss of appetite, marked insomnia). For such patients, there are a number of non-stimulant agents that serve as second-line treatments. Tricyclic antidepressants (TCAs) are the most studied of these drugs. They are superior to placebo in the treatment of ADHD and may reduce abnormal movements in patients with ADHD/tic disorder. TCAs often produce side effects of sedation, dry mouth, and constipation. Bupropion is superior to placebo in the treatment of ADHD and has a more favorable side-effect profile than the TCAs. A new selective norepinephrine reuptake inhibitor, atomoxetine, has been shown to be efficacious in the treatment of ADHD and has recently received an approvable letter from the Food and Drug Administration. The a-agonists clonidine and guanfacine have also been used as alternative agents in ADHD, though the controlled data are more limited. A recent controlled clinical trial suggests a combination of methylphenidate and clonidine has advantages in the treatment of comorbid ADHD and tics over either medication alone. Clinical guidelines for each of these agents, as well as their use in combination with stimulants in comorbid conditions, will be discussed.     

Stimulus-dependent dopamine release in attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is related to an attenuated and dysfunctional dopamine system. Normally, a high extracellular dopamine level yields a tonic dopaminergic input that down-regulates stimuli-evoked phasic dopamine responses through autoreceptors. Abnormally low tonic extracellular dopamine in ADHD up-regulates the autoreceptors so that stimuli-evoked phasic dopamine is boosted. The authors propose that these boosted phasic responses yield hypersensitivity to environmental stimuli in ADHD. Stimuli evoking moderate brain arousal lead to well-functioning performance, whereas either too little or too much stimuli attenuate cognitive performance. Strong, salient stimuli may easily disrupt attention, whereas an environment with impoverished stimuli causes low arousal, which is typically compensated for by hyperactivity. Stochastic resonance is the phenomenon that makes a moderate noise facilitate stimulus discrimination and cognitive performance. Computational modeling shows that more noise is required for stochastic resonance to occur in dopamine-deprived neural systems in ADHD. This prediction is supported by empirical data.     

Parent training for attention-deficit hyperactivity disorder: Its impact on parent functioning

This study examined changes in parent functioning resulting from parental participation in a behavioral parent training (PT) program specifically designed for school-aged children with attention-deficit hyperactivity disorder (ADHD). Relative to wait list controls, subjects who completed the nine-session PT program showed significant posttreatment gains in both child and parent functioning, which were maintained 2 months after treatment. In particular, there were PT-induced reductions in parenting stress and increases in parenting self-esteem, which accompanied parent-reported improvements in the overall severity of their child's ADHD symptoms. In addition to their statistical importance, these findings are discussed in terms of their clinical significance, utilizing methods developed by Jacobson and Truax (1991).This project was supported in part through BRSG grant S07RR05712-19 awarded to Arthur D. Anastopoulos by the Biomedical Research Support Program, Division of Research Resources, National Institutes of Health.     

Social functioning and emotional regulation in the attention deficit hyperactivity disorder subtypes

Compared 16 children with attention deficit hyperactivity disorder (ADHD) combined type (ADHD-C), 14 children with ADHD predominantly inattentive type (ADHD-I), and 17 controls on parent and teacher ratings of social status and performance, self-report of social knowledge and performance, and observations of behavior on an emotional regulation task. Analyses revealed distinct patterns of social dysfunction between ADHD subgroups. Children with ADHD-C were rated as showing more aggressive behavior; furthermore, they displayed emotional dysregulation characterized by high intensity and high levels of both positive and negative behavior. In contrast, children with ADHD-I were perceived as displaying social passivity and showed deficits in social knowledge on the self-report measure but did not evidence problems in emotional regulation. Regression analyses revealed that social performance, emotional regulation, and, to a lesser degree, social knowledge, were predictive of social status. The application of these findings to understanding the nature of the social deficits in the ADHD subtypes and directions for future research are discussed.     

Language and executive functioning skills of students with attention deficit/hyperactivity disorder (ADHD), and in reading comprehension difficulties (RCD)

The aim of this work was to study the specificity of deficits in linguistic and executive functioning of students with ADHD and with RCD and to determine the profile of deficits in the comorbid group (ADHD+RCD). Participants in the study were 84 students, ages 12-16 years divided into four groups with an equal number of subjects (N= 21): ADHD, RCD, ADHD+RCD and comparison group (without ADHD and without RCD). We measured vocabulary, oral comprehension, lexical access, verbal and visual working memory, inhibition and attention. The results show that the ADHD+RCD group presents the most important linguistic deficits, followed by the RCD group. On the other hand, the three clinical groups (ADHD, RCD and ADHD+RCD) display greater performance problems in working memory than the comparison group, whereas the two groups with ADHD had more problems in attention and inhibition. These results suggest the dissociation of linguistic and executive deficits that affect the RCD group and ADHD group to a greater extent, respectively. Lastly, the comorbid group showed deficits both in language and in executive skills. We discuss the implications of these findings for designing interventions.     

Parenting in mothers with and without attention-deficit/hyperactivity disorder

The authors examined the impact of maternal attention-deficit/hyperactivity disorder (ADHD) on parenting behaviors. Sixty mothers between the ages of 31 and 50 with (n = 30) and without (n = 30) ADHD and their 8- to 14-year-old children with ADHD completed self-report and laboratory measures of monitoring of child behavior, consistency in parenting, and parenting problem-solving abilities. These parenting behaviors were selected because of their established links to the development of child behavior problems. As predicted, mothers with ADHD were found to be poorer at monitoring child behavior and less consistent disciplinarians compared with mothers without ADHD. There was some evidence to support the prediction that mothers with ADHD were less effective at problem solving about childrearing issues than control mothers. The differences between the 2 groups of mothers persisted after child oppositional and conduct-disordered behavior were controlled. These results indicate that parenting is an area of functioning that requires more attention in adult ADHD research.     

Gait control in children with attention-deficit/hyperactivity disorder

The current profile of gait control in children with ADHD is incomplete and predominately based on children walking forward at a self-selected pace. There are no studies of potential gait deficits in this clinical population when walking in different directions in combination with varying rates of stepping that are freely selected and entrained to an external stimulus. The purpose of the current study was to address this lack of information by assessing gait of children aged 7–17 years with (n = 17) and without (n = 26) ADHD. Participants walked forward and backward along an electronically instrumented carpet at a self-selected stepping rate and in synchrony to a metronome that dictated an increased and decreased stepping rate. Using repeated measures analysis of covariance (ANCOVA) to assess spatiotemporal gait parameters, results showed that children with ADHD exhibited a significantly exaggerated, toes ‘turned out,’ foot position for all walking conditions compared to typically developing children. When walking backward, children with ADHD produced an increased step width, higher stepping cadence, and increased velocity. Additionally, coefficient of variation ratios indicated that children with ADHD produced greater variability of velocity, cadence, and step time for all walking conditions, and greater variability for stride length when walking at an increased stepping rate. Results were interpreted in terms of clinical significance and practical ramifications that inform rehabilitation specialists in designing therapies that ameliorate the reported gait deficits.     

A psychoanalytic perspective on attention-deficit/hyperactivity disorder

Psychoanalysts have tended to view the diagnosis of AD/HD either with skepticism or as a contraindication to analytic treatment. The author reviews the history of this puzzling diagnostic entity, which is estimated to account for up to fifty percent of child referrals, and suggests that a psychoanalytic perspective on the underlying disturbance in ego functioning helps to clarify the nature of the symptom picture. Whatever the etiology, which may be compound, she suggests that psychoanalytic treatment, most often in conjunction with psychopharmacological therapy, can address the core disturbance in ego integration that creates the familiar triad of inattention, impulsivity, and hyperactivity.