Neuropsychological analyses of comorbidity between reading disability and attention deficit hyperactivity disorder: in search of the common deficit

Measures of component reading and language skills, executive functions, and processing speed were administered to groups of children with attention deficit hyperactivity disorder (ADHD; n = 113), reading disability (RD; n = 109), both RD and ADHD (n = 64), and neither RD nor ADHD (n = 151). Groups with RD exhibited pronounced deficits on all measures of component reading and language skills, as well as significant weaknesses on measures of verbal working memory, processing speed, and response inhibition. Groups with ADHD exhibited weaknesses on all response-inhibition and processing speed tasks and were impaired on some measures of component reading skills and verbal working memory. The group with comorbid RD and ADHD exhibited the combination of the deficits in the RD-only and ADHD-only groups, providing evidence against the phenocopy and cognitive subtype hypotheses as explanations for the co-occurrence of RD and ADHD. Slow and variable processing speed was characteristic of all 3 clinical groups, suggesting that measures of this domain may be useful for future studies that search for the common genes that increase susceptibility to RD and ADHD.     

Neuropsychological profiles of children diagnosed as specific language impaired with and without hyperlexia.

This study compared the neuropsychological profiles of 46 children with Specific Language Impairment (SLI) and 16 children with SLI and Hyperlexia (SLI + H). The results indicated that the essential feature of Hyperlexia is Specific Language Impairment and not reading disability. Thus, Hyperlexia would be best conceptualized as a subgroup of Developmental Language Disorder rather than as a subgroup of Developmental Dyslexia. Further, the SLI + H group exhibited significantly better developed visual/spatial memory which, along with average visual perceptual skills, appears to be the major contributing factor to their elevated word recognition and spelling ability. Finally, it should be noted that both groups of children exhibited decreasing performance on tasks of immediate auditory/verbal memory as the language/semantic demands of the memory task increased. This finding appears to be the result of a limited capacity for immediate verbal processing and not the result of a deficit in verbal learning and recall.     

Abnormal executive function in attention deficit hyperactivity disorder: the effect of stimulant medication and age on spatial working memory

OBJECTIVE: This study sought to examine the factors associated with spatial working memory and the use of strategies to impairments in spatial working memory in children with attention deficit hyperactivity disorder (ADHD). The developmental trajectories for spatial working memory in medicated and medication na?ve children with ADHD were investigated. In addition, the effect of psychostimulant medication on deficits in spatial working memory was examined. METHOD: A cross-sectional study compared performance between 21 psychostimulant medicated children with ADHD, 27 medication na?ve children with ADHD and 26 matched control subjects on computerized tests of spatial memory and spatial working memory. RESULTS: Compared with the controls, performance in medication na?ve children with ADHD was significantly worse on the spatial working memory task. There was no difference in performance between the medicated children with ADHD and the control subjects on this same task, despite the ongoing symptoms of ADHD in the former group. The pattern of normal and abnormal performance in the ADHD groups was age-independent. CONCLUSIONS: Deficits in executive functions related to spatial working memory do occur in children with ADHD, although the magnitude of these deficits is not related to the child's age or the level of ADHD symptoms. These deficits were not present in the current sample of children who were receiving psychostimulant medication.     

Naming and verbal memory skills in adults with Attention Deficit Hyperactivity Disorder and Reading Disability

Research suggests that children with Attention Deficit Hyperactivity Disorder (ADHD) and Reading Disability (RD) can be differentiated based on their performance on measures of naming and verbal memory. It is not known whether this same pattern characterizes adults with these disorders. In this study, adults with and without ADHD and RD were compared on naming and verbal memory abilities. Results did not support the hypothesis that adults with ADHD and RD are significantly different from each other, or from a contrast group, on naming and verbal memory measures after controlling for Full-Scale IQ (FSIQ). These results were replicated across two sets of classification criteria used to identify diagnostic groups. Factors that could account for the inconsistency in research findings with children and adult subjects are discussed.     

Executive functioning in children with attention-deficit/hyperactivity disorder: combined type with and without a stimulant medication history

Behavioral and neuropsychological functioning in unmedicated children with attention-deficit/hyperactivity disorder (ADHD) who have a history of medication treatment (Rx) versus those who are treatment na?ve (TN) has, to our knowledge, not been previously studied. Ninety-four children in four groups (ADHD/Rx, ADHD/TN, learning disabilities [LD], and controls) were evaluated, while unmedicated, on measures of achievement, neuropsychological functioning, and behavior. The ADHD/Rx group performed significantly better than the TN group on writing, Stroop interference, and measures of attention, and performed as well as the control group on executive functioning, verbal working memory, and academics. Behaviorally, the ADHD groups showed more difficulty with mood and externalizing behaviors compared with the LD and control groups, with the ADHD/TN performing the most poorly. Findings suggest that the ADHD/Rx group shows better executive and academic functioning even when unmedicated.     

The relation between working memory components and ADHD symptoms from a developmental perspective

The objective was to examine the relations between attention deficit hyperactivity disorder (ADHD) symptoms and four working memory (WM) components (short-term memory and central executive in verbal and visuospatial domains) in 284 6-16-year-old children from the general population. The results showed that verbal and visuospatial short-term memory and verbal central executive uniquely contributed to inattention symptoms. Age interacted with verbal short-term memory in predicting inattention, with the relation being stronger in older children. These findings support the notion of ADHD as a developmental disorder, with changes in associated neuropsychological deficits across time. The results further indicate ADHD-related deficits in several specific WM components.     

Language in Italian children with Down syndrome and with specific language impairment

This article compares lexical and grammatical abilities of a mental-age-matched sample of Italian preschoolers with Down syndrome (DS), specific language impairment (SLI), or typical development. Results showed that the children with DS or with SLI performed significantly worse than did the typically developing children. Although no significant differences emerged in lexical abilities and morphosyntactic comprehension abilities between the children with DS or with SLI, significant differences did emerge in morphosyntactic production capacities. Qualitative analysis of the morphosyntactic errors revealed strong similarities between the two groups. The results are discussed in terms of the role of verbal memory abilities and the linguistic features of Italian.     

Differentiating Between Comorbidity and Symptom Overlap in ADHD and Early Onset Bipolar Disorder

Reported rates of comorbidity between early onset bipolar disorder (BD) and attention deficit hyperactivity disorder (ADHD) have a wide range, perhaps due to developmental issues and differences in interpretation of overlapping symptoms. We compared questionnaire-based and neuropsychological measures of inattention and impulsivity/hyperactivity, in children/adolescents with ADHD combined subtype (ADHD-C; n26), concurrent ADHD-C and BD (n15), BD (n25) with Controls (n69). Sub-analyses were performed on BD with and without inattention symptoms. The two ADHD-C groups displayed neuropsychological impairments that were not found in the BD group in spite of subjective and questionnaire-rated inattention. The findings caution against over-diagnosis of ADHD in BD.     

Neuropsychological performance deficits in adults with attention deficit/hyperactivity disorder.

Neuropsychological deficits in children diagnosed with attention deficit/hyperactivity disorder (ADHD) have been well documented utilizing various neuropsychological tests. Only recently has research begun to examine if similar deficits are present in adults with ADHD. A neuropsychological testing battery was constructed that assessed verbal learning and memory, psychomotor speed, and sustained attention--all demonstrated to be deficient in individuals with ADHD. Fifty-six self-referred nonmedicated adults with a DSM-IV diagnosis of ADHD and 38 normal comparison adults participated. ADHD adults demonstrated verbal and nonverbal memory deficits and decreased psychomotor speed compared to normal controls. Differences between ADHD and normal adults were not documented on traditional measures of executive functioning. A pattern of results emerged whereby ADHD adults' performance, particularly with regard to psychomotor speed, became more impaired as task complexity increased. This study's results largely corroborate similar neuropsychological testing results in ADHD children and recent ADHD adult findings, and support a frontal lobe dysfunction hypothesis of ADHD.     

Executive functioning and olfactory identification in young adults with attention deficit-hyperactivity disorder

Young adults with attention deficit-hyperactivity disorder (ADHD; N = 105) were compared with a control group (N = 64) on 14 measures of executive function and olfactory identification using a 2 (group) X 2 (sex) design. The ADHD group performed significantly worse on 11 measures. No Group X Sex interaction was found on any measures. No differences were found in the ADHD group as a function of ADHD subtype or comorbid oppositional defiant disorder. Comorbid depression influenced the results of only 1 test (Digit Symbol). After IQ was controlled for, some group differences in verbal working memory, attention, and odor identification were no longer significant, whereas those in inhibition, interference control, nonverbal working memory, and other facets of attention remained so. Executive function deficits found in childhood ADHD exist in young adults with ADHD and are largely not influenced by comorbidity but may be partly a function of low intelligence.     

Neuropsychological and academic functioning in preschool boys with attention deficit hyperactivity disorder

We compared 34 preschool boys with attention deficit hyperactivity disorder (ADHD) to 30 community comparison boys without behavioral problems on a battery of neuropsychological and academic achievement tests along with behavioral observations. The battery of 25 measures was reduced to 4 dimensions through dimensional (factor) analysis. Comparison of the 2 groups revealed that boys with ADHD performed more poorly than comparison boys on 2 of the 4 dimensions, these being motor control and working memory‐persistence. No differences were found on the dimensions of verbal learning‐memory or picture identification‐factual knowledge. The results suggest that achievement problems are evident early in development in clinic‐referred children with ADHD and may be related to deficiencies in more fundamental neuropsychological functions. These early deficits in motor control and working memory seem to be an inherent part of ADHD, supporting both the neuromaturational nature of the disorder and current efforts to more broadly conceptualize it as involving deficits in executive functions beyond the core problems in behavioral inhibition and sustained attention.     

Contextual abnormalities of saccadic inhibition in children with attention deficit hyperactivity disorder

Abnormalities of executive function are observed consistently in children with attention-deficit hyperactivity disorder (ADHD), and it is hypothesised that these arise because of disruption to a behavioural inhibition system. Executive and inhibitory functions were compared between unmedicated and medicated children with ADHD (combined type), age-matched healthy children and healthy adults. Executive functions were measured using a test of spatial working memory shown previously to be sensitive to ADHD and to stimulant medication. Inhibitory functions were measured using an ocular motor paradigm that required individuals to use task context to control the release of fixation. Context was set according to the probability that a target would appear at either of the two locations. In one block, targets appeared on 80% of trials. In the other block, targets appeared on 20% of trials. The ability to control the release of fixation was inferred from the fixation offset effect (FOE), or the difference in saccade latency when the current fixation is offset 200 ms prior to the onset of the saccade target (gap condition), compared with when there is no offset (overlap condition). Although the healthy children made more errors on the spatial working memory task than the healthy adults, there was no difference between the two groups in their ability to control fixation using context. Both showed a larger FOE when target probability was low. As expected, the unmedicated ADHD group made more errors on the spatial working memory test than the healthy children, although spatial working memory performance was normal in the medicated ADHD group. However, both the unmedicated and medicated ADHD groups were unable to modulate the FOE according to context, and this was due to their inability to voluntarily inhibit saccades when there was a low target probability. These data suggest that the context-based modulation of fixation release is not controlled by the same systems that control executive function. Furthermore, deficits in executive function and inhibitory control appear independent in children with ADHD.     

单一和双重干扰源对混合型注意缺陷多动障碍儿童干扰控制的影响

目的:探讨单一干扰源和双重干扰源对混合型注意缺陷多动障碍(ADHD)儿童的干扰控制的影响。方法:对25例符合美国精神障碍诊断与统计手册第4版(DSM-IV)诊断标准的门诊混合型ADHD儿童和25名性别、年龄和智力相匹配的对照组儿童,进行图形Stroop测验,通过操纵图片的颜色和形状特征,设置了单一干扰和双重干扰两种条件,比较两组被试的冲突效应量。结果:在单一干扰条件下,ADHD组的冲突效应量显著大于对照组(P0.05),而在双重干扰条件下,两组的冲突效应量差异无统计学意义(P0.05)。结论:本研究提示,在单一干扰源条件下,混合型ADHD儿童表现出干扰控制缺陷,但在双重干扰源条件下,混合型ADHD儿童的干扰控制表现与正常儿童差异不显著。     

不同亚型注意缺损多动障碍（ADHD）患儿智力结构分析

目的分析不同亚型多动症儿童的智力结构特征,探索不同亚型多动症儿童认知缺损发生机制,为多动症的临床诊断和治疗提供参考。方法随机抽取注意缺陷型、多动冲动型和混合型多动症儿童各60例,从学校抽取100例正常儿童作为对照,均采用中国韦氏儿童智力量表（c-WISC）进行智力测验,对各类儿童进行智力结构分析。结果多动症儿童韦氏总智商低于正常儿童（P〈0.01）,且智商变异性大,PIQ与VIQ不平衡发生率高于正常儿童;注意缺陷型言语智商高于多动冲动型和混合型（P〈0.01）,多动冲动型操作智商高于注意缺陷型（P〈0.01）,但和混合型无差异,混合型总智商低于其它两种亚型。结论多动症儿童智力受损是客观事实,不同多动症亚型智力结构和缺损程度存在差异,提示多动冲动型和注意缺陷型认知机制不完全相同,应对多动症患儿进行区别诊断和针对性治疗。     

Which neuropsychological functions predict various processing speed components in children with and without attention-deficit/hyperactivity disorder?

We identified statistical predictors of four processing speed (PS) components in a sample of 151 children with and without attention-deficit/hyperactivity disorder (ADHD). Performance on perceptual speed was predicted by visual attention/short-term memory, whereas incidental learning/psychomotor speed was predicted by verbal working memory. Rapid naming was predictive of each PS component assessed, and inhibition predicted all but one task, suggesting a shared need to identify/retrieve stimuli rapidly and inhibit incorrect responding across PS components. Hence, we found both shared and unique predictors of perceptual, cognitive, and output speed, suggesting more specific terminology should be used in future research on PS in ADHD.     

The profile of memory function in children with autism

A clinical memory test was administered to 38 high-functioning children with autism and 38 individually matched normal controls, 8-16 years of age. The resulting profile of memory abilities in the children with autism was characterized by relatively poor memory for complex visual and verbal information and spatial working memory with relatively intact associative learning ability, verbal working memory, and recognition memory. A stepwise discriminant function analysis of the subtests found that the Finger Windows subtest, a measure of spatial working memory, discriminated most accurately between the autism and normal control groups. A principal components analysis indicated that the factor structure of the subtests differed substantially between the children with autism and controls, suggesting differing organizations of memory ability.     

注意缺陷多动障碍综合征患儿睡眠结构的初探

目的 探讨注意缺陷多动障碍（ADHD）综合征患儿的睡眠结构，睡眠中痢性放电及睡眠周期性肢体运动（PLMS）的情况；比较ADHD各亚型问睡眠结构的差异。方法 利用多导睡眠监护仪对2005年6月至2006年11月在首都儿科研究所神经科门诊就诊的符合DSM-Ⅳ诊断标准的58例ADHD患儿及30名正常儿童进行整夜睡眠结构监测。结果 ADHD组58例，其中4例睡眠监测未完成，实际完成54例。ADHD组中混合型（ADHD—C）31例（57．4％，31／54），注意缺陷型（ADHD-I）15例（27．8％，15／54），多动／冲动型（ADHD．H）8例（14．8％，8／54）。①与对照组比较，ADHD组快速动眼期（REM）潜伏期短、睡眠潜伏期延长和睡眠效率降低，差异有统计学意义（P〈0．05）；②ADHD-C患儿睡眠Ⅱ期百分比较ADHD-I增加，差异有统计学意义（P〈0．05）；③ADHD组PLMS发生率为37．0％（20／54），对照组PLMS发生率为13．3％（4／30），差异有统计学意义（P〈0．05）；④ADHD组和对照组EEG未见痢性放电。结论 ①ADHD患儿存在REM睡眠结构的改变、入睡困难及睡眠效率降低；②睡眠Ⅱ期百分比的增多可使ADHD-C较ADHD-I有更多和更重的症状；③ADHD患儿睡眠过程中PLMS发生率较对照组显著升高，PLMS也是导致ADHD患儿睡眠质量下降的原因之一。     

Executive function and attention deficit hyperactivity disorder: stimulant medication and better executive function performance in children.

BACKGROUND: Executive function deficits have been reported repeatedly in children with Attention Deficit Hyperactivity Disorder (ADHD). Stimulant medication has been shown to be effective in improving cognitive performance on most executive function tasks, but neuropsychological tests of executive function in this population have yielded inconsistent results. Methodological limitations may explain these inconsistencies. This study aimed to measure executive function in medicated and non-medicated children with ADHD by using a computerized battery, the Cambridge Neuropsychological Test Automated Battery (CANTAB), which is sensitive to executive function deficits in older patients with frontostriatal neurological impairments. METHODS: Executive function was assessed in 30 children with ADHD: 15 were stimulant medication naive and 15 were treated with stimulant medication. These two groups were compared to 15 age, sex and IQ matched controls. RESULTS: The unmedicated children with ADHD displayed specific cognitive impairments on executive function tasks of spatial short-term memory, spatial working memory, set-shifting ability and planning ability. Impairments were also seen on spatial recognition memory and delayed matching to sample, while pattern recognition memory remained intact. The medicated children with ADHD were not impaired on any of the above executive function tasks except for deficits in spatial recognition memory. CONCLUSIONS: ADHD is associated with deficits in executive function. Stimulant medication is associated with better executive function performance. Prospective follow-up studies are required to examine these effects.     

Children With Specific Language Impairment: Quantitative and Qualitative Analysis of Dichotic Listening Performance

Specific language impairment (SLI) is one of the most common developmental disorders of higher cerebral function in children. This study was undertaken to examine the dichotic listening performance of children with SLI. Participants included 37 school-age children who underwent a comprehensive neuropsychological evaluation that included measures of cognitive ability, receptive and expressive language, visual-spatial perception-construction, immediate-working memory, and achievement and ratings of behavior-emotionality. In addition, each child was administered a free-recall consonant-vowel syllable dichotic listening task (30 pairs). Results indicated that, although the children with SLI exhibited a weak right-ear preference as a group, nearly 52% demonstrated a significant right-ear deficiency, whereas 29% exhibited left-ear deficiency and approximately 10% demonstrated bilateral-ear deficiency. The implication of these results is discussed with regard to their corresponding patterns of higher cortical dysfunction and their support for a qualitative differences model of SLI.     

Verbal mediation of cognition in children with specific language impairment

Private speech (PS) and inner speech (IS) are thought to be functionally important for children's and adults' cognition, but they have not been studied systematically in children with specific language impairment (SLI). Participants were 21 children with SLI (7-11 years, expressive or receptive verbal IQ ≤ 75, nonverbal IQ ≥ 84) and 21 age- and nonverbal IQ-matched controls. Participants completed three sets of Tower of London problems: one with no dual task (PS condition), one with articulatory suppression, and one while foot tapping (control condition). Participants also completed a digit span task. There was no group difference in the susceptibility of Tower of London performance to articulatory suppression, but the PS of the SLI group was less internalized than that of the controls on both tasks. The findings suggest that children with SLI experience a significant delay in the development of PS/IS, but that their PS/IS is effective for Tower of London performance in middle childhood. Findings are discussed with reference to the interpretation of the nonlinguistic deficits associated with SLI, and in terms of clinical implications.