Age and gender effects in EEG coherence: III. Girls with attention-deficit/hyperactivity disorder.

OBJECTIVE: This study investigated intrahemispheric and interhemispheric EEG coherences as a function of age in girls with different DSM-IV subtypes of Attention-Deficit/Hyperactivity Disorder (AD/HD). It completes a series of 3 studies aimed at clarifying developmental and gender impacts on the coupling between brain regions in this disorder. METHODS: Three groups of 40 children (AD/HD combined type, AD/HD inattentive type, and normal controls) participated. Each group contained 8 females in each of 5, 1-year age bands from 8 to 12 years. EEG was recorded from 21 sites during an eyes-closed resting condition. Wave-shape coherence was calculated for 8 intrahemispheric electrode pairs (4 in each hemisphere), and 8 interhemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. RESULTS: Developmental effects in intrahemispheric coherences at shorter and longer inter-electrode distances were not as predicted by Thatcher's two-compartment model, contrary to previous findings in boys. Females with AD/HD showed evidence of developmental delay and widespread anomalous elevations in coherence. Girls with AD/HD of the combined type showed similar but greater anomalies than girls with AD/HD of the inattentive type. CONCLUSIONS: Girls with AD/HD show coherence anomalies relative to age- and gender-matched controls, which differ substantially from those shown by boys with AD/HD. These coherence anomalies did not differ in nature between girls with different DSM-IV subtypes of AD/HD, suggesting that subtype differences in girls reflect only symptom severity. SIGNIFICANCE: The data reported here indicate qualitative differences in EEG coherences in girls with AD/HD compared with controls, and quantitative differences between girls with different subtypes of AD/HD. Both sets of effects differ in nature from those previously found in boys with AD/HD, showing the need to carefully consider gender in future studies of AD/HD.     

Absence of gender effects on attention deficit hyperactivity disorder: findings in nonreferred subjects

OBJECTIVE: In a previous study, the authors found that, compared with referred boys with attention deficit hyperactivity disorder (ADHD), girls are less likely to manifest comorbid disruptive behavior disorders and learning disabilities--characteristics that could adversely affect identification of ADHD in girls. However, because referral bias can affect outcome, these findings require replication in nonreferred groups of ADHD subjects. METHOD: The authors evaluated gender effects in a large group of nonreferred siblings (N=577) of probands with ADHD and non-ADHD comparison subjects. Ninety-eight of the nonreferred siblings (N=73 males, N=25 females) met the criteria for diagnosis of ADHD, and 479 (N=244 males, N=235 females) did not meet those criteria. All siblings were systematically and comprehensively assessed with measures of emotional, school, intellectual, interpersonal, and family functioning. The assessment battery used for the siblings was the same as that used for the probands. RESULTS: The nonreferred males and females with ADHD did not differ in DSM-IV subtypes of ADHD, psychiatric comorbidity, or treatment history. They also showed similar levels of cognitive, psychosocial, school, and family functioning. CONCLUSIONS: These findings suggest that the clinical correlates of ADHD are not influenced by gender and that gender differences reported in groups of subjects seen in clinical settings may be caused by referral biases.     

Specificity of quantitative EEG analysis in adults with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) in children and adolescents is characterised by excessive restlessness and an extremely poor concentration span, resulting in impulsive and disruptive behaviour. Clinical observation of ADHD in adults suggests that the early hyperactivity is diminished in terms of its impact on social and academic function, while impulsive-type behaviours remain unchanged. EEG studies in children and adolescents with ADHD have reported significantly more low-frequency power (predominantly theta) and less high-frequency power (predominantly beta) than in normal subjects. In normal children and adolescents, a decrease in theta power and an increase in beta power are found with increasing age, leading some researchers to interpret the EEG anomalies in ADHD as evidence of developmental delay. Studies of adults with ADHD compared with normal adult control subjects have found a reduction in the difference between the two groups, suggesting that the reduced beta activity apparent in ADHD children and adolescents changes with age. Adults with ADHD thus appear to have elevated low-frequency power as their predominant EEG difference from normal control subjects. The present study examined whether this EEG profile was specific to adult ADHD patients. Quantitative EEGs were recorded at rest in an eyes-open condition and used to compare 50 adult patients diagnosed with ADHD with 50 non-ADHD subjects (who presented for ADHD assessment but failed to meet the diagnostic criteria) and 50 control subjects. The ADHD group differed from both the non-ADHD and the control groups on the basis of elevated theta activity. The ADHD and control groups did not differ in beta activity, but relative theta was reduced and relative beta power was elevated in the non-ADHD group compared with both the ADHD and control groups. These results suggest that quantitative EEG may be used to differentiate ADHD adults from both normal adults and adults who display some of the symptoms of ADHD, but fail to meet the diagnostic criteria of ADHD.     

Long-term effects of theta/beta neurofeedback on EEG power spectra in children with attention deficit hyperactivity disorder

ObjectiveNeurofeedback has been proposed as an effective alternative for pharmacological treatment in children with attention-deficit/hyperactivity disorder (ADHD), with potentially long-term and delayed benefits. However, the specificity of such long-term behavioral improvements remains inconclusive and therefore additional research into the neurophysiological effects of neurofeedback is needed. We compared long-term effects of theta/beta neurofeedback (NFB) to methylphenidate (MPH) and physical activity (PA, semi-active control intervention) on electroencephalogram (EEG) power spectra. Based on the vigilance stabilization model, we hypothesized further reductions in theta and alpha power in the NFB compared to the control groups.MethodEEG power spectra (theta, alpha and beta) during resting and task conditions were recorded at pre-, post-intervention and 6-months follow-up in 67 children, aged 7–13 (NFB: n = 24, MPH: n = 23, or PA: n = 20).ResultsAnalyses revealed no power spectra differences at follow-up between MPH and NFB (range p = .165–.905) and PA and NFB (range p = .172–.822).ConclusionsNo evidence was found for the specificity of theta/beta NFB at follow-up.SignificanceThis was the first study into long-term neurophysiological effects of theta/beta NFB. Future studies are encouraged to explore both specific and non-specific mechanisms of NFB.Clinical trials registration: Train Your Brain? Exercise and neurofeedback intervention for ADHD, https://clinicaltrials.gov/show/NCT01363544, Ref. No. NCT01363544.     

Sustained attention in sensory modulation disorder and attention deficit/hyperactivity disorder

BackgroundThere are high comorbidity rates between sensory modulation disorder (SMD) and attention deficit hyperactivity disorder (ADHD). Knowledge regarding the objective neuropsychological differentiation between them is scarce.AimThis study examines the effects of SMD and ADHD on a sustained attention task with and without aversive auditory conditions.MethodSixty six young adult females were tested on the Conjunctive - Continuous Performance Task-Visual (CCPT-V) measuring sustained attention, under two conditions: 1) aversive condition (with the three most aversive sounds chosen by the participant), and 2) non-aversive condition (without sounds).ResultsBoth the SMD and ADHD factors exhibited performance deficits in the sustained attention task. All study participants performed worse on both sustained attention and speed of processing when aversive sounds were present.ConclusionWe conclude that impaired sustained attention cannot differentiate between SMD and ADHD. Hence, these results should be taken under consideration in the assessment process of ADHD vs. SMD.     

EEG evidence for a new conceptualisation of attention deficit hyperactivity disorder.

OBJECTIVES: This study investigated the presence of electroencephalographic (EEG) clusters within a sample of children with the inattentive type of attention-deficit/hyperactivity disorder (ADHD).METHODS: Subjects consisted of 100 boys with ADHD and 40 age-matched controls. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, and relative power in the delta, theta, alpha and beta bands. Factor analysis was used to group sites into 3 regions; frontal, central and posterior. These data were subjected to cluster analysis.RESULTS: Two distinct EEG clusters of children with the inattentive type of ADHD were found. These were characterised by (a) increased high-amplitude theta with deficiencies of delta and beta activities, and (b) increased slow wave and deficiencies of fast wave activity.CONCLUSIONS: These two subtypes are independent of current diagnostic categories, and consist of a cortically hypoaroused group and a group typified by a maturational lag in central nervous system (CNS) development. These results support a re-conceptualisation of ADHD based on the CNS abnormality underlying the disorder rather than the behavioural profile of the child. This has the potential to add a level of predictive validity, which is currently lacking in the present diagnostic systems.     

Examining the diagnostic utility of EEG power measures in children with attention deficit/hyperactivity disorder.

OBJECTIVE: This study investigated the diagnostic utility of EEG power during eyes-closed resting conditions for children with attention-deficit/hyperactivity disorder (AD/HD). METHODS: Subjects consisted of 253 boys with AD/HD combined type and 67 age-matched controls. EEG was recorded from 21 sites during an eyes-closed resting condition and was Fourier transformed to provide estimates for total power and absolute and relative power in delta, theta, alpha and beta bands. Factor analysis was used to group sites into frontal, central and posterior regions, with these data subjected to cluster analysis. Logistic regression was performed on the entire AD/HD sample versus control, for AD/HD clusters versus control, and then for each AD/HD cluster independently versus control, using total, absolute and relative power measures. RESULTS: Logistic regression performed on the clusters independently produced the best classification results, with a sensitivity of 89.0% and a specificity of 79.6%, with an overall classification accuracy of 87.0%. CONCLUSIONS: The obtained classification results are supportive of an independent diagnostic test for AD/HD based on EEG power at rest. SIGNIFICANCE: This is the first study to investigate sensitivity and specificity of EEG power for AD/HD in a resting condition.     

药物假日与注意缺陷/多动障碍(英文)

The concept of ' drug holidays' ( defined as the structured interruption of pharmacological treatment[1] ) in the management of attention deficit hyperactivity disorder ( ADHD) is well established,but poorly researched[1] . The question is whether there is indeed a justifiable basis for the practice. In the opinion piece by Professors Du and Wang[2] ,they argue that on the balance of available evidence it is not justified. Herein lies the issue—the evidence. In reality significant numbers     

Gait in attention deficit hyperactivity disorder

Abstract Background Cognitive function and the loading of attention presumably play an important role in gait as well as in fall risk, but previous work has not demonstrated this in any cause-and-effect way. Objectives To gain insight into the relationship between gait and cognitive function, we sought: (1) To compare the gait rhythmicity (stride time variability) of children with attention deficit hyperactivity disorder (ADHD) to controls, (2) To test the hypothesis that dual tasking leads to increased stride-to-stride variability in ADHD, and (3) To test whether pharmacological treatment that relieves ADHD symptoms reduces stride-to-stride variability. Patients and Methods Gait was quantified in children with ADHD and in age-matched healthy controls under single task and dual task conditions on three occasions: off medications (both groups) and, in the ADHD group, after double blinded, randomized administration of methylphenidate (MPH) or placebo. Results At baseline, children with ADHD tended to walk with increased stride-to-stride variability compared to the controls during the single task condition (p = 0.09). During dual task walking, stride time variability was significantly reduced in the children with ADHD (p < 0.004), but not in the controls. In the children with ADHD, the placebo did not significantly affect stride-to-stride variability or the dual tasking response. In contrast, stride time variability was significantly reduced on MPH (p < 0.001) such that dual tasking no longer affected variability. Conclusions The present findings demonstrate alterations in the gait of children with ADHD, support a cause and effect link between cognitive function and gait, and suggest that enhancement of attention abilities may, in certain populations, improve gait rhythmicity.     

Somatosensory evoked potentials in attention deficit/hyperactivity disorder and tic disorder.

OBJECTIVE: Both attention deficit/hyperactivity disorder (ADHD) and chronic tic disorder (TD) are hyperkinetic disorders. These disorders often coexist with each other and frequently have sensory components. Therefore, we hypothesized that they might have a common pathophysiology involving the somatosensory system, especially hyper-excitabilities of primary somatosensory area. METHODS: To evaluate sensory system excitability, we examined somatosensory evoked potentials (SEP) elicited by median nerve stimulation in 18 children with ADHD and 18 children with TD. RESULTS: Three children with ADHD and 8 children with TD showed giant SEP and the peak-to-peak amplitude for N20-P25 was also significantly greater than that obtained from normally developing children (P<0.05 for ADHD and P<0.01 for TD). Children with TD had significant left-ward asymmetry of N20-P25 (P<0.01) and higher left-hemispheric N20-P25 than children with ADHD (P<0.05). CONCLUSIONS: Although hyper-excitability of the primary somatosensory area is a common characteristic for ADHD and TD, its severity, especially in the left-hemisphere, differs (i.e. TD has left-ward hyper-excitability). SIGNIFICANCE: The possibility remains that hyper-excitability of the primary somatosensory area is a reason why these disorders often coexist with each other and left-ward hyper-excitability of the primary somatosensory area is a unique feature of TD described for the first time.     

EEG coherence in children with attention-deficit/hyperactivity disorder and comorbid oppositional defiant disorder.

OBJECTIVES: This study is the first to investigate EEG coherence differences between two groups of children with attention-deficit/hyperactivity disorder combined type (AD/HD), with or without comorbid oppositional defiant disorder (ODD), and normal control subjects. METHODS: Each group consisted of 20 males. All subjects were between the ages of 8 and 12 years, and groups were matched on age. EEG was recorded during an eyes-closed resting condition from 21 monopolar derivations. Wave-shape coherence was calculated for 8 intrahemispheric electrode pairs (4 in each hemisphere), and 8 interhemispheric electrode pairs, within each of the delta, theta, alpha, and beta bands. RESULTS: Children with comorbid AD/HD and ODD had intrahemispheric coherences at shorter inter-electrode distances significantly reduced from those apparent in children with AD/HD without comorbid ODD. Such reduced coherences in the comorbid group appeared to wash out coherence elevations previously noted in AD/HD studies. CONCLUSIONS: The present results suggest that, rather than suffering an additional deficit, children with AD/HD and comorbid ODD show significantly less CNS impairment than AD/HD patients without comorbid ODD. SIGNIFICANCE: These results have treatment implications, suggesting that behavioural training, perhaps using family-based cognitive behavioural therapy, could be useful for those children with AD/HD and comorbid ODD. This should focus on the ODD symptoms, in association with a medication regime focussed on the AD/HD symptoms.     

Genes and attention deficit hyperactivity disorder

The initial molecular genetic studies of attention deficit hyperactivity disorder (ADHD) evaluated two candidate genes (DAT and DRD4) suggested by dopamine theories of this common disorder and its treatment with stimulant medication. The initial reports of weak associations with ADHD have been replicated by many (but not all) investigators, as is expected for genes with small effects. This literature is reviewed, along with emerging literature generated by active research groups investigating additional genes that might contribute to the genetic basis of this complex disorder.     

Treatment of attention deficit hyperactivity disorder with neurotherapy.

Significant public health concerns exist regarding our current level of success in treating ADHD. Medication management is very helpful in 60-70% of patients. Side effects, lack of compliance and the fact that stimulant medications cannot be given late in the day limit the benefits largely to school hours. While stimulants improve behavior and attention, less of an effect has been noted on academic and social performance. Continuing concerns exist about long-term safety, and studies on long-term cardiovascular and neurophysiological effects have not been carried out. Neurotherapy for ADHD offers an effective alternate for patients whose treatment is limited by side effects, poor medication response and in cases in which the patients and/or their parents refuse to consider medications. Studies indicate clinical improvement is largely related to measurable improvements in the EEG signature, evidenced by declining theta/beta ratios over frontal/central cortex and/or reduced theta/alpha band amplitudes.     

Pharmacodynamics of pemoline in attention deficit disorder with hyperactivity.

The onset, duration, and offset of pemoline action to improve cognitive performance is examined intensively in 25 prepubescent males suffering from attention-deficit disorder with hyperactivity (ADDH). The purpose was to characterize the pharmacodynamics of pemoline in ADDH patients through correlation of plasma pemoline concentration with psychometric measures of memory search efficiency and paired-associates learning, with the physiological effect of pemoline on dopaminergic transmission concurrently measured by analysis of plasma prolactin response. The effect of pemoline on neuroprocessing is apparent within the first 2 hours after administration with an inverse relationship between plasma pemoline and prolactin concentration present at hour one only (r = 0.84; p = 0.005). Pemoline therapy for 3 weeks does not significantly affect area under the curve for pemoline or prolactin nor did the effect on memory search efficiency decrease, suggesting no apparent tolerance.     

Multicomponent attention deficits in attention deficit hyperactivity disorder

The aim of this study was to examine the specific aspects of attention, such as selective attention, sustained attention, and short-term memory in children with attention deficit hyperactivity disorder, combined subtype (ADHD-C). A total of 40 children with a diagnosis of ADHD from the 4th edition of the Diagnostic and Statistical Manual, aged 6-11 years old were compared with 40 controls matched for age and gender on a battery of tests. Short-term memory span and attention was measured by Visual Aural Digit Span Test-Revised. Stroop test and the Turkish version of Cancellation Test were used to assess selective and sustained attention, respectively. In order to check for factor structure in two groups on the test scores, principal component analysis was conducted for both groups separately. Relative to the comparison children, children with ADHD showed significant deficits on tests that are related to different aspects of attention. The results are consistent with the theories explaining the biological basis of ADHD by scattered attention networks in the brain, which have reciprocal dynamic interactions. Further comparative studies are needed to elucidate whether the cognitive processes that are known to be assessed by these tests are specific to ADHD.     

Impaired habituation in children with attention deficit hyperactivity disorder.

OBJECTIVE: To investigate whether children with attention deficit hyperactivity disorder show impaired habituation to peripheral stimuli. METHOD: We compared the Troxler effect (the ability to habituate to a peripheral visual stimulus when presented with a competing central visual stimulus) in groups of 23 children with attention deficit hyperactivity disorder and 15 controls matched for age, gender, and IQ. RESULTS: Regression analyses revealed a statistically significant effect of diagnosis on fading (P = 0.03), with attention deficit hyperactivity disorder subjects taking longer to fade to a peripheral stimulus than controls. Additional analyses revealed a significant interaction between diagnosis and visual field; control subjects showed similar fading times to stimuli presented in the right and left visual fields (13.25 vs. 12.96 seconds), while the attention deficit hyperactivity disorder group showed much slower fading in the right than in the left visual field (18.64 vs. 15.00 seconds). CONCLUSIONS: Our results suggest that children with attention deficit hyperactivity disorder have impaired visual habituation. The findings provide evidence of frontal dysfunction in attention deficit hyperactivity disorder and suggest that impaired habituation contributes to off-task behavior in children with the disorder.     

Atomoxetine improved response inhibition in adults with attention deficit/hyperactivity disorder.

BACKGROUND: Atomoxetine, a highly selective noradrenaline reuptake inhibitor (SNRI), shows efficacy in the treatment of attention-deficit/hyperactivity disorder (ADHD). Compared with psychostimulants, atomoxetine has a distinct mode of brain action and potentially lower addictive potential. Studies have yet to assess whether atomoxetine improves cognition following a single oral dose in ADHD. METHODS: Twenty-two adults with DSM-IV ADHD were administered a single oral dose of atomoxetine (60 mg) in a placebo-controlled double-blind crossover design. Cognitive effects were assessed using stop-signal, sustained attention, spatial working memory, and set-shifting paradigms. Normative cognitive data from 20 healthy volunteers were collected for comparison. RESULTS: The ADHD patients under placebo conditions showed response inhibition and working memory deficits compared with healthy volunteers. Atomoxetine treatment in the ADHD patients was associated with shorter stop-signal reaction times and lower numbers of commission errors on the sustained attention task. CONCLUSIONS: Atomoxetine improved inhibitory control, most likely via noradrenergically mediated augmentation of prefrontal cortex function. These results have implications for understanding the mechanisms by which atomoxetine exerts beneficial clinical effects and suggest novel treatment directions for other disorders of impulsivity.