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.     

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.     

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.     

Predictors of physical aggression in children with attention-deficit/hyperactivity disorder

The present investigation examined factors that predict physical aggression in children with attention-deficit/hyperactivity disorder (ADHD). Stepwise, multiple regression-analyses were used to examine predictors of children's physical aggression as rated by parents at a 1-year follow-up point and by teachers at both 1- and 2-year follow-up points. Early parent and teacher ratings of verbal aggression (ie, cursing, teasing, and threatening) accounted for the greatest proportion of the variance in physical aggression ratings obtained at follow-up. None of the other predictor variables, including early ratings of physical aggression and ADHD behaviors, contributed significant additional variance beyond that accounted for by early verbal aggression ratings. Temporal and cross-informant analyses revealed that the relationship between verbal aggression and later physical aggression was situation-specific for teacher ratings but not parent ratings. Although physical aggression may emerge early in development, these data suggest that verbal aggression represents a stable, temperamental characteristic that may be of greater value than early physical aggression for predicting later physically aggressive acts.     

Sustained attention and executive functioning performance in attention-deficit/hyperactivity disorder.

The aim of this study was to further refine the cognitive phenotype of attention-deficit/hyperactivity disorder (ADHD), with respect to the ability to sustain attention and executive functioning. Participants were 34 boys with ADHD (combined type) and 28 normal controls. The groups were closely matched for age and IQ. All participants were 12 years of age. Both groups performed a computerized sustained attention task and a response interference task. Measures related to speed, accuracy, and time on task were collected. We found that children with ADHD performed slower, less accurately, more impulsively, and with less stability than controls. Both groups produced more errors with increasing time on task, reflecting reduced vigilance. Importantly, no interaction with time on task was found. The overall pattern of results suggests that measures related to accuracy are more informative than measures related to speed of responding in refining the cognitive phenotype of 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.     

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.     

Cognitive-behavioral depression treatment for mothers of children with attention-deficit/hyperactivity disorder

An adaptation of the Coping With Depression Course (CWDC) was evaluated in mothers of children with attention-deficit/hyperactivity disorder (ADHD), a population at risk for depression. Mothers were randomly assigned to receive the CWDC either immediately following an intensive summer treatment program targeting their child's behavior or after a wait-list period. Measures of maternal functioning, cognitions about child behavior, parent-child and marital relationship quality, child behavior, and ADHD-related family impairment were obtained at pretreatment, posttreatment, and 5-month follow-up. The CWDC resulted in improvements in maternal depressive symptoms, maternal self-esteem, child-related cognitions, and family impairment at posttreatment compared to a wait-list control group that were maintained at follow-up. Findings suggest that the CWDC is a promising intervention for mothers of children with ADHD, particularly those with current depressive symptomatology.     

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.     

Processing affective stimuli in children with attention-deficit hyperactivity disorder.

Neuropsychological investigations have suggested a contribution of right hemisphere dysfunction in attention-deficit hyperactivity disorder (ADHD). Right hemisphere dysfunction has been implicated in deficits of attention, motor impersistence, and processing emotion-laden stimuli. The current study investigated the ability of ADHD children to perceive emotional stimuli in the form of facial expressions and speech intonation. The subjects consisted of 37 ADHD and 37 control children aged 7 to 12 years. ANCOVA analysis indicated that ADHD children demonstrate mild-to-moderate deficits in the perception of affect. Furthermore, deficits in attention may contribute to inaccurate or incomplete encoding of stimulus properties. The results lend tentative support for the notion that the right cerebral hemisphere may play a critical role in ADHD.     

Autonomic correlates of attention-deficit/hyperactivity disorder and oppositional defiant disorder in preschool children

Numerous studies have revealed autonomic underarousal in conduct-disordered adolescents and antisocial adults. It is unknown, however, whether similar autonomic markers are present in at-risk preschoolers. In this study, the authors compared autonomic profiles of 4- to 6-year-old children with attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD; n = 18) with those of age-matched controls (n = 20). Children with ADHD and ODD exhibited fewer electrodermal responses and lengthened cardiac preejection periods at baseline and during reward. Although group differences were not found in baseline respiratory sinus arrhythmia, heart rate changes among ADHD and ODD participants were mediated exclusively by parasympathetic withdrawal, with no independent sympathetic contribution. Heart rate changes among controls were mediated by both autonomic branches. These results suggest that at-risk preschoolers are autonomically similar to older externalizing children.     

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.     

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.     

Validity of the parenting scale for parents of children with attention-deficit/hyperactivity disorder

The present study examined the validity of the parenting scale for parents of elementary school-aged children with attention-deficit/hyperactivity disorder (ADHD). Parents from 109 families with children who had been diagnosed with ADHD (106 mothers and 93 fathers) and from 70 families with non-problem children (69 mothers and 59 fathers) completed the parenting scale and reported on their children's behavior problems. Factor analyses revealed two interpretable factors for both mothers and fathers, corresponding to the overreactivity and laxness factors identified in previous studies of the parenting scale. Overreactivity and laxness scores were significantly higher for mothers and fathers of ADHD children than of non-ADHD children; this effect appeared to be accounted for by comorbid aggression and conduct problems among ADHD children. Results support the validity of the parenting scale for use with parents of ADHD children.     

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.