Colour perception in ADHD

Attention-deficit/hyperactivity disorder (ADHD) is associated with unexplained impairments on speeded naming of coloured stimuli. These deficits may reflect hypofunctioning retinal dopaminergic mechanisms impairing particularly blue-yellow colour discrimination. Colour perception and rapid colour naming ability were investigated in 14 children with ADHD and 13 healthy peers matched for age, gender, and IQ, using the Farnsworth-Munsell 100 Hue Test (FMT) and the Stroop-Colour-Word test. Children with ADHD committed more errors on the FMT, particularly on discrimination of colours along the blue-yellow axis, and were slower on Stroop subtests involving colour naming. However, the latter deficit was accounted for similarly by blue-yellow and red-green discrimination abilities. Blue-yellow colour perception problems in ADHD contribute to but do not fully explain the observed slowed colour naming.     

Developing ADHD

Over the past 50 years the concept of attention deficit/hyperactivity disorder (ADHD) has developed from the notion of a specific form of brain dysfunction to that of a heterogeneous set of related behaviours. The great advances in genetics, neuroimaging and neuropsychiatry have made it one of the best understood forms of complex mental disturbance – but much remains to be done to translate understanding into practice. More effective treatment may come from identifying and treating more specific components of disorder and by a focus on identifying the factors determining course in the longer term so that they, as well as the core features of disorder, can become targets for intervention.     

Managing ADHD

Medication can help, but a multimodal approach that also includes educational and psychological services works best for most children. Second of two parts.     

Heart rate and reinforcement sensitivity in ADHD

BACKGROUND: Both theoretical and clinical accounts of attention-deficit/hyperactivity disorder (ADHD) implicate a dysfunctional reinforcement system. This study investigated heart rate parameters in response to feedback associated with reward and response cost in ADHD children and controls aged 8 to 12. METHODS: Heart rate responses (HRRs) following feedback and heart rate variability (HRV) in the low frequency band (.04-.08 Hz), a measure of mental effort, were calculated during a time production paradigm. Performance was coupled to monetary gain, loss or feedback-only in a cross-over design. RESULTS: Children with ADHD exhibited smaller HRRs to feedback compared to controls. HRV of children with ADHD decreased when performance was coupled to reward or response cost compared to feedback-only. HRV of controls was similar across conditions. CONCLUSIONS: Children with ADHD were characterised by (a) possible abnormalities in feedback monitoring and (b) motivational deficits, when no external reinforcement is present.     

Sleep and alertness in children with ADHD

OBJECTIVE: To evaluate sleep and alertness and to investigate the presence of possible underlying sleep/wake disorders in children with attention-deficit/hyperactivity disorder (ADHD). METHOD: After 3 nights of adaptation in a room reserved for sleep studies in the department of child psychiatry, children underwent polysomnography (PSG) followed by the Multiple Sleep Latency Test (MSLT) and reaction time tests (RT) during the daytime. Thirty boys diagnosed as having ADHD (DSM-IV), aged between 5 and 10 years, and 22 age- and sex-matched controls participated in the study. All children were medication-free and showed no clinical signs of sleep and alertness problems. RESULTS: No significant differences in sleep variables were found between boys with ADHD and controls. The mean latency period was shorter in children with ADHD. Significant differences were found for MSLT 1, 2 and 3 (p < .05). Mean reaction time was longer in children with ADHD, with significant differences in all tests (p < .05). Number and duration of sleep onsets measured by the MSLT correlated significantly with the hyperactivity-impulsivity and inattentive-passivity indices of the CTRS and CPRS. CONCLUSION: Children with ADHD were more sleepy during the day, as shown by the MSLT, and they had longer reaction times. These differences are not due to alteration in the quality of nocturnal sleep. The number of daytime sleep onsets and the rapidity of sleep-onsets measured as MSLT were found to be pertinent physiological indices to discriminate between ADHD subtypes. These results suggest that children with ADHD have a deficit in alertness. Whether this deficit is primary or not requires further studies.     

Event rate and event-related potentials in ADHD

BACKGROUND: It has been repeatedly found that performance of children with attention deficit hyperactivity disorder (ADHD) is more impaired when a long inter-stimulus interval (ISI) is used than when a short ISI is used. According to the cognitive-energetic model, this may reflect difficulty in remaining in an optimal motor activation state because of insufficient effort allocation. METHOD: Event-related potentials (ERPs) were evaluated during a Go/No-Go task that incorporates a condition with a fast and a slow presentation rate. RESULTS: ADHD, whether or not comorbid with oppositional defiant/conduct disorder (ODD/CD), was associated with a steeper increase in reaction time (RT) from the fast to the slow condition accompanied by a missing increment of the parietal P3. Speed of responding was found to be correlated with P3 amplitude. In the fast condition, children with ADHD made more errors of commission, accompanied by a smaller No-Go N2, a component thought to be related to inhibition; however, after controlling for ODD/CD these differences disappeared. CONCLUSIONS: The association between the steeper increase in RT and reduced parietal P3s may indicate that the children with ADHD did not allocate enough extra effort to adjust to a potentially under-activated state. However, the event rate effects could not account for all of the differences between groups and also early automatic information processing stages seem disturbed in this disorder as indexed by larger P2 amplitudes. Alternative explanations are discussed.     

Auditory conflict processing in ADHD

Background: Impaired cognitive control has been implicated as an important developmental pathway to attention deficit/hyperactivity disorder (ADHD). Cognitive control is crucial to suppress interference resulting from conflicting information and can be measured by Stroop‐like tasks. This study was conducted to gain insight into conflict processing in children with ADHD. Methods: Event‐related potentials (ERPs) were recorded in an auditory Stroop task. Twenty‐four children with ADHD were compared with 24 control children (aged 8–12 years). Results: No deficit in interference control was found on the auditory Stroop task in children with ADHD. Children with ADHD responded more slowly, less accurately and more variably compared to controls. No differences between the groups occurred in the early conflict‐related ERPs. However, the difference between the congruent and the incongruent condition in the 450–550 ms time window was absent in the ADHD group compared to controls. In addition, the conflict sustained potential was found frontally in the ADHD group but parietally in the control group. Conclusions: These ERP findings suggest that children with ADHD evaluate conflict to a lesser extent and differ in the way their brains select appropriate responses during conflict compared with controls.     

注意缺陷障碍的临床研究

目的　探讨注意缺陷障碍 (ADHD)儿童的诊断、分型和性别差异。方法　根据DSM IV诊断标准 ,对2 0 0 3年 10月至 2 0 0 4年 3月因多动、注意力不集中、成绩下降而就诊上海儿童医学中心儿保门诊的 2 32例儿童进行诊断和分型 ;应用韦氏智力量表对诊断为ADHD儿童进行智力测试 ,比较男女儿童在智力结构及核心症状发生率的差异 ,并对核心症状进行聚类分析。结果　确诊为ADHD者 118例 ,女性儿童算术、拼图量表分明显落后于男性儿童 ,且语言智商、操作智商、总智商也低于男性儿童 (P <0 0 5 ) ;ADHD亚型中 ,以注意缺陷型为最多 ,其次为混合型 ,共 4 1例 ,多动冲动型最少 ,3个亚型中 ,男女发生率无性别差异 ;ADHD儿童核心症状的聚类分析结果有 4类 ;ADHD和非ADHD儿童不同性别核心症状的比较显示 :女性ADHD和非ADHD儿童之间的差异没有男性明显。结论　因多动、注意问题就诊的儿童中一半为ADHD ,其分型无性别差异。ADHD女性儿童智力明显落后于男性儿童。ADHD核心症状聚类分析有 4类。女性ADHD ,尤其多动冲动型的诊断过程中需考虑我国的文化差异。     

Cognitive strengths and deficits in schoolchildren with ADHD

BACKGROUND: Few studies provide detailed analyses of the various aspects of the entire cognitive profile of children with ADHD. MATERIAL AND METHODS: Cognitive test data were analysed for 10- to 11-year-old children with (1) ADHD, (2) subthreshold ADHD and (3) milder attention and/or learning problems, and compared with normative data. RESULTS: Thirty-two had ADHD and 10 met the criteria for subthreshold ADHD, prevalence rates of 5.4% and 1.6%, respectively. On a group level, children with ADHD/subthreshold ADHD, and those with milder attention and/or learning problems had almost identical cognitive profiles for the 13 subtests comprising the WISC III, with particularly low results on the arithmetic, coding, information and digit span subtests (ACID profile). When analyzed individually, a complete or incomplete ACID profile (three of four subtests) was equally common in children with ADHD/subthreshold ADHD and in children with milder problems, found in about 1/5. The relative strengths of both groups were in areas demanding logical thinking, reasoning and common sense. CONCLUSION: The specific ACID profile is as common in children with ADHD as in those with minor attention and/or learning problems. The cognitive weaknesses reflected in the ACID profile might play a role as an underlying factor in various developmental disorders.     

Differences between preschool children with ODD, ADHD, and ODD+ADHD symptoms

BACKGROUND: This study examines differences between children (ages 3 to 6 years) who have the symptoms of oppositional defiant disorder (ODD) with or without attention-deficit/hyperactivity disorder (ADHD), ADHD alone, and a nonODD/ADHD comparison group. Parent (N=595) and teacher (N=538) ratings were obtained for children attending the same community early childhood programs and for youngsters evaluated in an outpatient clinic (N=224) using a DSM-IV-referenced rating scale. RESULTS: Differences between symptom groups varied depending on how they were configured (teacher versus parent ratings) and setting (clinic versus community). In general, the ODD+ADHD group received the highest (and the comparison group the lowest) ratings of severity for the symptoms of other disorders, difficulties with peers, and developmental deficits. Moreover, the clinical impact of comorbidity was largely additive. Differences between youngsters with ODD versus ADHD symptoms were most apparent for teacher-defined groups in the community sample and parent-defined groups in the clinic sample. CONCLUSIONS: Collectively, these findings provide preliminary evidence for the notion that ODD and ADHD may constitute distinct clinical entities in preschool-aged children and suggest that informant may be an important consideration in the formulation of diagnostic criteria.