Working memory interference control deficit in children referred by teachers for ADHD symptoms.

It has been hypothesised that children with Attention Deficit/Hyperactivity Disorder (ADHD) present memory problems, including working memory deficits. This research is aimed at finding clearer evidence of a working memory deficit in these children. In the first study 22 children that had been referred by teachers as having ADHD symptoms were compared with a control group. Their performance on a listening span test, drawn up by De Beni, Palladino, Pazzaglia, and Cornoldi (1998), was investigated. In this task the subjects were asked to select the names of animals in word strings and to remember the last word in each string. In a second study, 34 children with ADHD symptoms and 50 control children were presented with a visuospatial working memory task mirroring the verbal task used in Study 1. In both studies, the children with ADHD symptoms had difficulty in remembering the last item in the string and had a higher number of intrusions when memorising items that were not in the final position. The results were interpreted that children with ADHD symptoms have working memory problems because they are not capable of suppressing information that initially has to be processed, and subsequently excluded from memory. This particular difficulty can be interpreted as an inhibitory processing deficit. The implications of the results in understanding learning difficulties in children with ADHD are discussed.     

Time-based prospective memory difficulties in children with ADHD and the role of time perception and working memory

Time-based prospective memory (PM) is the ability to remember to perform an intended action at a given time in the future. It is a competence that is crucial for effective performance in everyday life and may be one of the main causes of problems for individuals who have difficulty in planning and organizing their life, such as children with attention deficit/hyperactivity disorder (ADHD). This study systematically examines different aspects of time-based PM performance in a task that involves taking an action at a given future time in a group of 23 children with ADHD who were compared with a matched group of typically-developing (TD) children. The children were asked to watch a cartoon and then answer a questionnaire about its content (ongoing task). They were also asked to press a key every 2 minutes while watching the cartoon (PM task). The relationships of time perception and verbal working memory with PM performance were examined by administering appropriate tasks. The results showed that the children with ADHD were less accurate than the TD children in the PM task and exhibited less strategic time-monitoring behavior. Time perception was found to predict PM accuracy, whereas working memory was mainly involved in time-monitoring behavior, but this applied more to the TD group than to the ADHD group, suggesting that children with ADHD are less able to use their cognitive resources when meeting a PM request.     

Competing Core Processes in Attention-Deficit/Hyperactivity Disorder (ADHD): Do Working Memory Deficiencies Underlie Behavioral Inhibition Deficits?

The current study examined competing predictions of the working memory and behavioral inhibition models of ADHD. Behavioral inhibition was measured using a conventional stop-signal task, and central executive, phonological, and visuospatial working memory components (Baddeley 2007) were assessed in 14 children with ADHD and 13 typically developing (TD) children. Bootstrapped mediation analyses revealed that the visuospatial working memory system and central executive both mediated the relationship between group membership (ADHD, TD) and stop-signal task performance. Conversely, stop-signal task performance mediated the relationship between group membership and central executive processes, but was unable to account for the phonological and visuospatial storage/rehearsal deficits consistently found in children with ADHD. Comparison of effect size estimates for both models suggested that working memory deficits may underlie impaired stop-signal task performance in children with ADHD. The current findings therefore challenge existing models of ADHD that describe behavioral inhibition as a core deficit of the disorder.     

注意缺陷多动障碍(ADHD)儿童的工作记忆:基础加工缺陷还是执行功能问题

为探索注意缺陷多动障碍(ADHD)儿童言语工作记忆缺陷的机制,研究采用了言语n-back任务比较了正常儿童与注意缺陷多动障碍儿童的工作记忆成绩。结果表明:在更新水平为0次时,ADHD儿童与正常儿童的成绩没有显著差异,但在更新水平为1次和2次时,ADHD儿童的记忆成绩均显著低于正常儿童,效应量指标(Cohen′d)分别达到了1.31和1.63;另外,在更新难度对记忆成绩的影响上,ADHD儿童表现出了更大的更新代价,效应量指标(Cohen′d)达到了1.54,处在很高的水平。结论认为ADHD儿童在记忆的基础性加工上并不存在明显缺陷,其更大的更新代价表明ADHD儿童在言语工作记忆的执行加工(更新操作)上的缺陷。     

Working memory deficits in boys with attention deficit/hyperactivity disorder (ADHD): An examination of orthographic coding and episodic buffer processes

The episodic buffer component of working memory was examined in children with attention deficit/hyperactivity disorder (ADHD) and typically developing peers (TD). Thirty-two children (ADHD = 16, TD = 16) completed three versions of a phonological working memory task that varied with regard to stimulus presentation modality (auditory, visual, or dual auditory and visual), as well as a visuospatial task. Children with ADHD experienced the largest magnitude working memory deficits when phonological stimuli were presented via a unimodal, auditory format. Their performance improved during visual and dual modality conditions but remained significantly below the performance of children in the TD group. In contrast, the TD group did not exhibit performance differences between the auditory- and visual-phonological conditions but recalled significantly more stimuli during the dual-phonological condition. Furthermore, relative to TD children, children with ADHD recalled disproportionately fewer phonological stimuli as set sizes increased, regardless of presentation modality. Finally, an examination of working memory components indicated that the largest magnitude between-group difference was associated with the central executive. Collectively, these findings suggest that ADHD-related working memory deficits reflect a combination of impaired central executive and phonological storage/rehearsal processes, as well as an impaired ability to benefit from bound multimodal information processed by the episodic buffer.     

“热”执行对注意缺陷多动障碍和阅读障碍儿童言语工作记忆的影响

ADHD儿童在与背外侧前额叶(DLPFC)相关的"冷"执行功能上的缺陷已大量证实,但在与眼眶和中前额叶皮层(OMPFC)相关的"热"执行功能上,ADHD儿童是否存在缺陷则未可知。与儿童赌博任务实验范式(该任务中"热"启动对"冷"执行起到抑制作用)不同,本研究考察趣味言语N-back任务是否对ADHD和阅读障碍儿童的成绩有促进作用。枯燥N-back任务考察的是言语工作记忆的纯认知特征,而趣味任务则卷入了"热"执行对"冷"执行的影响。结果表明,在枯燥任务上,ADHD和阅读障碍儿童的成绩均明显低于正常儿童,二者之间差异不显著,在趣味任务成绩上,ADHD儿童与正常儿童的成绩没有显著差异,而阅读障碍儿童成绩落后于正常控制组和ADHD组,在成绩变化的趋势上,ADHD儿童在趣味任务上成绩明显提高,而阅读障碍儿童则无明显改善。结果说明ADHD和阅读障碍儿童的言语工作记忆均存在明显的缺陷,但是机制不同,"热"执行对提高ADHD的言语工作记忆有明显的促进作用,ADHD的"冷"执行缺陷能够通过"热"执行的调节得到改善。     

The role of interference control in working memory: A study with children at risk of ADHD

The study aimed to test whether the impairment in a working memory task observed in children at risk of ADHD was due to a lack of control of interfering information being processed whilst carrying out the memory task. Two groups of children at risk of ADHD with or without a learning disability (reading impairment) were compared to a control group in a working memory task. Activation of irrelevant items was tested with a lexical decision task presented immediately after the final recall in about half of the trials. Results showed a poor working memory performance in children at risk of ADHD and reading disability associated with a larger activation of irrelevant information than that of control children. Results indicated that the to-be-excluded and interfering items are still highly accessible to working memory in children that fail the working memory task. The examination of working memory and interference control of children at risk of ADHD with a learning disability revealed a counterintuitive picture of children with poor working memory showing better recall/activation of processed information. This picture is consistent with a view of working memory related to an efficient inhibitory control that influences cognitive functioning.     

The role of interference control in working memory: a study with children at risk of ADHD

The study aimed to test whether the impairment in a working memory task observed in children at risk of ADHD was due to a lack of control of interfering information being processed whilst carrying out the memory task. Two groups of children at risk of ADHD with or without a learning disability (reading impairment) were compared to a control group in a working memory task. Activation of irrelevant items was tested with a lexical decision task presented immediately after the final recall in about half of the trials. Results showed a poor working memory performance in children at risk of ADHD and reading disability associated with a larger activation of irrelevant information than that of control children. Results indicated that the to-be-excluded and interfering items are still highly accessible to working memory in children that fail the working memory task. The examination of working memory and interference control of children at risk of ADHD with a learning disability revealed a counterintuitive picture of children with poor working memory showing better recall/activation of processed information. This picture is consistent with a view of working memory related to an efficient inhibitory control that influences cognitive functioning.     

Reading Comprehension in Children with ADHD: Cognitive Underpinnings of the Centrality Deficit

We examined reading comprehension in children with ADHD by assessing their ability to build a coherent mental representation that allows them to recall central and peripheral information. We compared children with ADHD (mean age 9.78) to word reading-matched controls (mean age 9.89) on their ability to retell a passage. We found that even though children with ADHD recalled more central than peripheral information, they showed their greatest deficit, relative to controls, on central information—a centrality deficit (Miller and Keenan, Annals of Dyslexia 59:99–113, 2009). We explored the cognitive underpinnings of this deficit using regressions to compare how well cognitive factors (working memory, inhibition, processing speed, and IQ) predicted the ability to recall central information, after controlling for word reading ability, and whether these cognitive factors interacted with ADHD symptoms. Working memory accounted for the most unique variance. Although previous evidence for reading comprehension difficulties in children with ADHD have been mixed, this study suggests that even when word reading ability is controlled, children with ADHD have difficulty building a coherent mental representation, and this difficulty is likely related to deficits in working memory.     

前摄抑制对儿童注意缺陷多动障碍(ADHD)和阅读障碍的言语工作记忆的影响

ADHD和阅读障碍儿童在言语工作记忆上的缺陷得到了大量研究的证实,但是二者机制并不相同,前摄抑制对工作记忆容量产生了不利的影响,主要影响的也是中央执行功能。研究将最近探测任务和n-back任务相结合,直接比较被试在最近负探测和非最近负探测条件下记忆成绩的差异,以考察前摄抑制对两种障碍言语工作记忆的影响,被试是60名障碍儿童(阅读障碍和ADHD)和17名正常儿童,年龄均在7至12岁之间。结果发现,受前摄抑制的影响,正常被试和障碍被试成绩均明显下降,具体而言,ADHD和ADHD伴随阅读障碍组成绩大幅下滑(26.44%,28.44%),程度明显高于正常儿童和阅读障碍儿童(14.62%,15.84%),后两者差异并不明显,这说明前摄抑制是影响工作记忆容量的重要因素,并且ADHD儿童更加容易受到前摄抑制的影响,这是导致其工作记忆成绩缺损的重要原因,而阅读障碍儿童能够像正常儿童一样,在一定程度上处理前摄抑制,ADHD和阅读障碍组在言语工作记忆缺损机制上存在差异。     

Writing abilities and the role of working memory in children with symptoms of attention deficit and hyperactivity disorder

The writing abilities of children with ADHD symptoms were examined in a simple dictation task, and then in two conditions with concurrent verbal or visuospatial working memory (WM) loads. The children with ADHD symptoms generally made more spelling mistakes than controls, and the concurrent loads impaired their performance, but with partly different effects. The concurrent verbal WM task prompted an increase in the phonological errors, while the concurrent visuospatial WM task prompted more non-phonological errors, matching the Italian phonology, but not the Italian orthography. In the ADHD group, the children proving better able to cope with a concurrent verbal WM load had a better spelling performance too. The ADHD and control groups had a similar handwriting speed, but the former group’s writing quality was poorer. Our results suggest that WM supports writing skills, and that children with ADHD symptoms have general writing difficulties, but strength in coping with concurrent verbal information may support their spelling performance.     

Impaired Consonant Trigrams Test (CTT) performance relates to everyday working memory difficulties in children with Autism Spectrum Disorders

Individuals with Autism Spectrum Disorders (ASD) often struggle with complex tasks, such as those requiring divided attention (simultaneously completing two independent tasks) that also place high demands on working memory. Prior research shows that divided attention is impaired in adults and children with ASD and is related to ASD and comorbid attention deficit/hyperactivity disorder (ADHD) symptoms, but the impact on everyday functioning is unclear. Because ADHD symptoms are associated with poor divided attention and working memory performance in children with ASD, we also examined ADHD symptoms as moderators of divided attention performance. We examined performance on the Consonant Trigrams Test (CTT) between high-functioning 8- to 13-year-olds with ASD (n?=?28) and typically developing controls (n?=?18) matched on age and IQ. In the ASD group, we also correlated performance with ADHD symptoms and behavior ratings of everyday working memory. CTT performance in children with ASD was significantly worse than in matched controls. A significant correlation between CTT performance and everyday working memory was observed, but CTT performance was not related to comorbid ADHD symptoms in the ASD group. Divided attention with high working-memory demands is a relative weakness in children with high-functioning ASD; this weakness relates to everyday functioning, and it is independent from ADHD symptoms. That ADHD symptoms are not associated with divided attention performance is inconsistent with one prior investigation, which likely results from using different divided attention tasks in the two studies.     

Developmental change in the relation between executive functions and symptoms of ADHD and co‐occurring behaviour problems

In a sample of 92 children aged 6–13 years this study investigates the normal developmental change in the relation between executive functioning (EF) and the core behavioural symptoms associated with attention deficit hyperactivity disorder (ADHD) (hyperactivity/impulsivity and inattention) as well as symptoms often co‐occurring with childhood hyperactivity (conduct‐ and internalizing problems). EF was assessed by using multiple tests grouped through prior factor analysis, resulting in cognitive measures relating to disinhibition, speed/arousal, verbal working memory, non‐verbal working memory, and fluency. The results showed that although disinhibition was positively related to hyperactivity/impulsivity and inattention mainly for the youngest age group, there were no significant age effects for these relations. Instead, age effects were found for the relations between speed/arousal and inattention as well as for the relations between verbal working memory/fluency and inattention. In the oldest age group poor performance on these cognitive measures was associated with high ratings of inattention. For the total sample a relation was obtained between disinhibition and hyperactivity/impulsivity as well as between both working memory measures and internalizing problems. In conclusion, the results from this study suggest that poor inhibition is most clearly associated with ADHD symptoms for younger children, whereas poor functioning with regard to later developing and more complex executive functions such as working memory and fluency is associated with ADHD symptoms for older children. Copyright © 2006 John Wiley & Sons, Ltd.     

Time Reproduction in Children With ADHD: Motivation Matters

The primary goal of this study was to examine whether children with ADHD have a true deficit in subjective time sense, or whether their impairment reflects a motivational deficit. Thirty children with ADHD and 30 matched control children completed two versions of a time reproduction paradigm (“Regular” and “Enhanced”) in which motivational level was manipulated by the addition of positive sham feedback and the prospect of earning a reward. A secondary goal was to investigate performance on measures of working memory and behavioural inhibition, and how those constructs relate to time reproduction in the context of Barkley’s (1997a) model of ADHD. Children with ADHD performed significantly better on the motivating ‘Enhanced’ versus the Regular time reproduction paradigm, although they continued to perform significantly worse than controls on both tasks. Control children exhibited no reliable change in performance between versions of the task. Significant group differences were also observed on the working memory and behavioural inhibition tasks. We discuss the impact of motivation, working memory, and behavioural inhibition on time reproduction performance.     

Time reproduction in children with ADHD: motivation matters.

The primary goal of this study was to examine whether children with ADHD have a true deficit in subjective time sense, or whether their impairment reflects a motivational deficit. Thirty children with ADHD and 30 matched control children completed two versions of a time reproduction paradigm ("Regular" and "Enhanced") in which motivational level was manipulated by the addition of positive sham feedback and the prospect of earning a reward. A secondary goal was to investigate performance on measures of working memory and behavioural inhibition, and how those constructs relate to time reproduction in the context of Barkley's (1997a) model of ADHD. Children with ADHD performed significantly better on the motivating 'Enhanced' versus the Regular time reproduction paradigm, although they continued to perform significantly worse than controls on both tasks. Control children exhibited no reliable change in performance between versions of the task. Significant group differences were also observed on the working memory and behavioural inhibition tasks. We discuss the impact of motivation, working memory, and behavioural inhibition on time reproduction performance.     

Verbal fluency over time as a measure of automatic and controlled processing in children with ADHD

The performance of ADHD children on semantic category fluency (SCF) versus initial letter fluency (ILF) tasks was examined. For each participant, word production was recorded for each 15-s time slice on each task. Performance on both fluency tasks was compared to test the hypothesis that children with ADHD are characterized by a performance deficit on the ILF task because performance on this task is less automated than performance on the SCF. Children classified with ADHD (N = 20) were compared to children with other psychopathology (N = 118) and healthy controls (N = 130). Results indicated that the groups could not be differentiated by the total number of words produced in 60 s in either fluency task. As hypothesized, a significant interaction of group by productivity over time by type of fluency task was found: ADHD children had more problems finding words in the first 15 s of the IFL than did children in the other two groups, and as compared with their performance on the SCF. Results were taken to indicate that children with ADHD symptoms show a delay in the development of automating skills for processing abstract verbal information.     

Time reproduction, working memory, and behavioral inhibition in children with ADHD.

Barkley (1997a) proposed that the central deficit in Attention Deficit Hyperactivity Disorder (ADHD) is in behavioral inhibition, resulting in deficits both in working memory and sense of time. To test this theory, 21 children with ADHD and a matched sample (ages 6-13) completed a variety of tasks that measured behavioral inhibition, working memory, attention, and time reproduction. Children with ADHD performed significantly below controls on measures of inhibition, attention, and time reproduction. They did not differ significantly from controls, however, on tasks of working memory. In addition, performance on the working memory tasks was not correlated with the time reproduction task. We discuss the relevance of these results in the context of current theories of ADHD.     

Working memory deficit in children with mathematical difficulties: a general or specific deficit?

This study examined whether children with mathematical difficulties (MDs) or comorbid mathematical and reading difficulties have a working memory deficit and whether the hypothesized working memory deficit includes the whole working memory system or only specific components. In the study, 31 10-year-olds with MDs and 37 10-year-olds with both mathematical and reading difficulties were compared with 47 age-matched and 50 younger controls (9-year-olds) on a number of working memory tasks. Compared with the age-matched controls, both groups of children with MDs performed worse on tasks tapping the central executive (e.g., visual matrix span) and the phonological loop (e.g., word span). More important, the MD group performed worse than the younger controls on the counting span task, whereas the group with comorbid mathematical and reading difficulties performed worse on the counting span task and the visual matrix span task. These findings provide support for the assumption that children with MDs have a working memory deficit. More specifically, children with MDs have a central executive deficit connected to concurrent processing and storage of numerical and visual information.     

不同特征维度下ADHD儿童的任务切换特点

本研究采用双向刺激设置,通过操纵两实验的特征维度,以考察任务维度对ADHD儿童任务切换的影响。结果发现,在两个实验中,相对于正常组儿童,ADHD儿童在任务切换上都表现出缺损。当注意维度相同时,ADHD儿童在固定顺序上的切换损耗大于随机顺序,但在跨维度任务中,ADHD儿童在固定顺序上的切换损耗则小于随机顺序,这与正常儿童的表现模式不一致。该结果表明,工作记忆会对ADHD儿童产生影响,但这取决于任务的特征维度是否一致。     

Executive functions in kindergarteners with high levels of disruptive behaviours

Executive function (EF) deficits have yet to be demonstrated convincingly in children with disruptive behaviour disorders (DBD), as only a few studies have reported these. The presence of EF weaknesses in children with DBD has often been contested on account of the high comorbidity between DBD and attention‐deficit/hyperactivity disorder (ADHD) and of methodological shortcomings regarding EF measures. Against this background, the link between EF and disruptive behaviours in kindergarteners was investigated using a carefully selected battery of EF measures. Three groups of kindergarteners were compared: (1) a group combining high levels of disruptive behaviours and ADHD symptoms (COMB); (2) a group presenting high levels of disruptive/aggressive behaviours and low levels of ADHD symptoms (AGG); and (3) a normative group (NOR). Children in the COMB and AGG groups presented weaker inhibition capacities compared with normative peers. Also, only the COMB group showed weaker working memory capacities compared with the NOR group. Results support the idea that preschool children with DBD have weaker inhibition capacities and that this weakness could be common to both ADHD and DBD.