Adrenomedullary function during cognitive testing in attention-deficit/hyperactivity disorder

Metabolic fingerprinting of dogs with idiopathic epilepsy receiving a ketogenic medium-chain triglyceride (MCT) oil

Consumption of medium-chain triglycerides (MCT) has been shown to improve seizure control, reduce behavioural comorbidities and improve cognitive function in epileptic dogs. However, the exact metabolic pathways affected by dietary MCT remain poorly understood. In this study, we aimed to identify changes in the metabolome and neurotransmitters levels relevant to epilepsy and behavioural comorbidities associated with the consuming of an MCT supplement (MCT-DS) in dogs with idiopathic epilepsy (IE). Metabolic alterations induced by a commercial MCT-DS in a population of 28 dogs with IE were evaluated in a 6-month multi-centre, prospective, randomised, double-blinded, controlled cross-over trial design. A metabolic energy requirement-based amount of 9% MCT or control oil was supplemented to the dogs' stable base diet for 3 months, followed by the alternative oil for another 3 months. A validated, quantitative nuclear magnetic resonance (NMR) spectroscopy platform was applied to pre- and postprandially collected serum samples to compare the metabolic profile between both DS and baseline. Furthermore, alterations in urinary neurotransmitter levels were explored. Five dogs (30%) had an overall reduction in seizure frequency of ≥50%, and were classified as MCT-responders, while 23 dogs showed a ≤50% reduction, and were defined as MCT non-responders. Amino-acid metabolism was significantly influenced by MCT consumption compared to the control oil. While the serum concentrations of total fatty acids appeared similar during both supplements, the relative concentrations of individual fatty acids differed. During MCT supplementation, the concentrations of polyunsaturated fatty acids and arachidonic acid were significantly higher than under the control oil. β-Hydroxybutyric acid levels were significantly higher under MCT supplementation. In total, four out of nine neurotransmitters were significantly altered: a significantly increased γ-aminobutyric acid (GABA) concentration was detected during the MCT-phase accompanied by a significant shift of the GABA-glutamate balance. MCT-Responders had significantly lowered urinary concentrations of histamine, glutamate, and serotonin under MCT consumption. In conclusion, these novel data highlight metabolic changes in lipid, amino-acid and ketone metabolism due to MCT supplementation. Understanding the metabolic response to MCT provides new avenues to develop better nutritional management with improved anti-seizure and neuroprotective effects for dogs with epilepsy, and other behavioural disorders.

Urinary Neurotransmitter Patterns Are Altered in Canine Epilepsy

Epilepsy is the most common chronic neurological disease in humans and dogs. Epilepsy is thought to be caused by an imbalance of excitatory and inhibitory neurotransmission. Intact neurotransmitters are transported from the central nervous system to the periphery, from where they are subsequently excreted through the urine. In human medicine, non-invasive urinary neurotransmitter analysis is used to manage psychological diseases, but not as yet for epilepsy. The current study aimed to investigate if urinary neurotransmitter profiles differ between dogs with epilepsy and healthy controls. A total of 223 urine samples were analysed from 63 dogs diagnosed with idiopathic epilepsy and 127 control dogs without epilepsy. The quantification of nine urinary neurotransmitters was performed utilising mass spectrometry technology. A significant difference between urinary neurotransmitter levels (glycine, serotonin, norepinephrine/epinephrine ratio, ɤ-aminobutyric acid/glutamate ratio) of dogs diagnosed with idiopathic epilepsy and the control group was found, when sex and neutering status were accounted for. Furthermore, an influence of antiseizure drug treatment upon the urinary neurotransmitter profile of serotonin and ɤ-aminobutyric acid concentration was revealed. This study demonstrated that the imbalances in the neurotransmitter system that causes epileptic seizures also leads to altered neurotransmitter elimination in the urine of affected dogs. Urinary neurotransmitters have the potential to serve as valuable biomarkers for diagnostics and treatment monitoring in canine epilepsy. However, more research on this topic needs to be undertaken to understand better the association between neurotransmitter deviations in the brain and urine neurotransmitter concentrations in dogs with idiopathic epilepsy.

Effects of Intranasal Epinephrine on Cerebrospinal Fluid Epinephrine Pharmacokinetics, Nasal Mucosa, Plasma Epinephrine Pharmacokinetics, and Cardiovascular Changes

PURPOSE

We aimed to assess intranasal (IN) epinephrine effects on cerebrospinal fluid (CSF) absorption, nasal mucosa quality, plasma epinephrine pharmacokinetics (PK), and cardiovascular changes in dogs.

METHODS

CSF epinephrine concentration was measured and nasal mucosa quality was evaluated after IN epinephrine 4 mg and one or two 4 mg doses (21 min apart), respectively. Maximum plasma concentration [C_max], time to C_max [T_max], area under the curve from 0 to 120 min [AUC_0-120], and cardiovascular effects were evaluated after epinephrine IN (4 and 5 mg) and intramuscular (IM; 0.3 mg). Clinical observations were assessed.

RESULTS

After epinephrine IN, there were no changes in CSF epinephrine or nasal mucosa. C_max, T_max, and AUC_1-120 were similar following epinephrine IN and IM. Epinephrine IN versus IM increased plasma epinephrine at 1 min (mean ± SEM, 1.15 ± 0.48 for 4 mg IN and 1.7 ± 0.72 for 5 mg IN versus 0.47 ± 0.11 ng/mL for 0.3 mg IM). Epinephrine IN and IM produced similar heart rate and ECG results. Clinical observations included salivation and vomiting.

CONCLUSIONS

Epinephrine IN did not alter CSF epinephrine or nasal tissue and had similar cardiovascular effects as epinephrine IM. Epinephrine IN rapidly increased plasma epinephrine concentration versus epinephrine IM.

Coupling of respiration and attention via the locus coeruleus: Effects of meditation and pranayama

The locus coeruleus (LC) has established functions in both attention and respiration. Good attentional performance requires optimal levels of tonic LC activity, and must be matched to task consistently. LC neurons are chemosensitive, causing respiratory phrenic nerve firing to increase frequency with higher CO₂ levels, and as CO₂ level varies with the phase of respiration, tonic LC activity should exhibit fluctuations at respiratory frequency. Top-down modulation of tonic LC activity from brain areas involved in attentional regulation, intended to optimize LC firing to suit task requirements, may have respiratory consequences as well, as increases in LC activity influence phrenic nerve firing. We hypothesize that, due to the physiological and functional overlaps of attentional and respiratory functions of the LC, this small neuromodulatory nucleus is ideally situated to act as a mechanism of synchronization between respiratory and attentional systems, giving rise to a low-amplitude oscillation that enables attentional flexibility, but may also contribute to unintended destabilization of attention. Meditative and pranayama practices result in attentional, emotional, and physiological enhancements that may be partially due to the LC's pivotal role as the nexus in this coupled system. We present original findings of synchronization between respiration and LC activity (via fMRI and pupil dilation) and provide evidence of a relationship between respiratory phase modulation and attentional performance. We also present a mathematical dynamical systems model of respiratory-LC-attentional coupling, review candidate neurophysiological mechanisms of changes in coupling dynamics, and discuss implications for attentional theory, meditation, and pranayama, and possible therapeutic applications.

Effectiveness of methylphenidate and PUFA for the treatment of patients with ADHD: A double-blinded randomized clinical trial

BACKGROUND

In some children with ADHD, sub-optimal levels of various nutrients including PUFA especially omega-3 has been observed, and contradictory reports exist on the results of studies conducted on the positive therapeutic effects of PUFA in patients with ADHD.

OBJECTIVE

The aim of this study was to investigate the effectiveness of methylphenidate and PUFA on treatment of patients with ADHD in Zahedan, Iran.

METHODS

In this clinical trial, 40 children between 6 and 12 years of age with ADHD were investigated in Zahedan in 2014. Patients were randomly divided into two groups of methylphenidate plus PUFA and methylphenidate plus placebo. ADHD rating scale was filled before and after the study for patients of both groups. Finally, data were analyzed using SPSS18, paired-samples t-test and chi-square.

RESULTS

Mean age of patients was 2.9±1.8 years. Thirty-three children (82.5%) were boys and seven children (17.5%) were girls. Mean severity of signs in the group under methylphenidate plus PUFA treatment was 39.9±4.9 before treatment and 20.1±6.0 after 8 weeks of treatment (p<0.001). Mean severity of signs in the group under methylphenidate plus placebo treatment was 41.2±2.7 before treatment and 26.1±9.0 after 8 weeks of treatment (p<0.001). Mean reduction in the severity of symptoms in the group under methylphenidate therapy was 19.7±5.9 and in PUFA and placebo group it was 15.1±9.3 (p<0.067). Response to treatment (a reduction of at least 25% in the signs) in the group taking methylphenidate plus PUFA was 90% (18 patients) and in methylphenidate plus placebo group, it was 60% (12 patients) (p=0.028).

CONCLUSION

This study shows that PUFA is an efficient nutrient to treat ADHD and it can be used to treat patients. However, definitive conclusion requires repeating the study with a larger sample and longer study period.

TRIAL REGISTRATION

The trial was registered at the Iranian Registry of Clinical Trials (http://www.irct.ir) with the Irct ID: IRCT2015092724209N2.

FUNDING

The authors received no financial support for the research, authorship, and/or publication of this article.

Learning disorders in children with epilepsy

INTRODUCTION

Learning Disorders (LD) are defined as disorders that interfere with academic performance or with daily activities that require reading, writing or mathematical skills in subjects with a normal intelligence quotient (IQ). The prevalence of LD in the general population has been found to be 2-10%, and reading disorders are the most frequent subtype. Epilepsy is one of the most common serious neurological disorders in childhood. LD are more common in children with epilepsy than in the general population. As a consequence, the risk of cognitive impairment in children with epilepsy is high, and a review of the literature needs to be fully presented.

METHODS

Narrative review including articles regarding LD in children with various epileptic syndromes published in the international medical literature.

RESULTS

LD are more frequent among children with epilepsy. The etiology is multifactorial, being affected by the type of epileptic syndrome, the age of onset and the antiepileptic treatment being selected. LD can be either permanent or state-dependent. Each category has different treatment protocols and prognosis.

CONCLUSIONS

Despite the fact that the findings of the studies discussed in our article support the evidence that epilepsy in childhood impairs the cognitive function, we should not underestimate the role of demographic and psychosocial factors on academic performance of children with epilepsy. Despite the high prevalence of LD, a healthy family and school environment can help reduce its impact on the patient's quality of life.

Neurotransmitters excreted in the urine as biomarkers of nervous system activity: validity and clinical applicability

Strategies for managing the nervous system are numerous while methods of evaluating the nervous system are limited. Given the physiological importance of neurotransmitters as signaling molecules in the nervous system, the measurement of neurotransmitters has significant potential as a clinical tool. Of all the biological fluids that can be utilized, urinary neurotransmitter testing, due to its stability, sensitivity, and non-invasiveness, is the desired method to analyze nervous system function. Increasing use of this technology in a clinical setting demands a review of its feasibility, utility, and clinical value. We review the current body of literature pertaining to the mechanism of neurotransmitter transport across the blood-brain barrier as well as neurotransmitter filtration and excretion by the kidneys. In addition, this review summarizes the historical use of urinary neurotransmitter assessment to diagnose pheochromocytoma. Early research also correlated urinary assessment of neurotransmitters to various clinical symptoms and treatments of which we present research only for depression, ADHD, and inflammation because of the abundant amount of research in these areas. Finally, we review the limitations and challenges of urinary neurotransmitter testing. Taken together, evidence suggests that neurotransmitters excreted in the urine may have a place in clinical practice as a biomarker of nervous system function to effectively assess disturbances and monitor treatment efficacy.

Variants of the SLC6A3 (DAT1) polymorphism affect performance monitoring-related cortical evoked potentials that are associated with ADHD

Although the 10-repeat (10R) variant of the dopamine transporter gene (DAT1 or SLC6A3) is suggested to be a risk allele for Attention Deficit Hyperactivity Disorder (ADHD) no relationships between DAT1 and measures of cognition in children with ADHD have yet been demonstrated. We studied neurophysiological correlates of performance monitoring during a feedback-based learning task by measuring cortical event-related potentials (ERPs) in a group of 65 10-13-year-old children half of whom were diagnosed as ADHD. The first part of the study investigates correlations between parent-reported behaviour problems and several performance monitoring components, while the second part investigates the relationship between DAT1 and these components. Specifically ADHD problems correlated significantly with an error-related positivity (Pe) and a feedback-anticipatory negativity (the SPN). Only these two components discriminated between the DAT1 10/10R and 9R carriers. The 10/10R carriers showed a smaller Pe to errors and a smaller SPN in anticipation of negative feedback, particularly with learning.

Increased cortisol after stress is associated with variability in response time in ADHD children

PURPOSE

Children with attention-deficit/hyperactivity disorder (ADHD) often perform poorly during cognitive tests. We sought to evaluate cortisol as potential moderator of performance in mentally challenging tasks in children with ADHD.

MATERIALS AND METHODS

Ninety clinic-referred children with ADHD were studied. Cortisol contents in saliva were measured before and after administration of a continuous performance test (CPT).

RESULTS

Pre and post CPT cortisol levels were similar in 68 children. Children whose cortisol level increased after testing ( n = 22 ) displayed a significantly longer response time and increased response time variability scores as compared to children who did not display increase of cortisol after the CPT test. Even after controlling for the effects of response time and anxiety, the changes in cortisol levels were associated with effect on response time variability.

CONCLUSION

The patients who showed an increased cortisol level after stress displayed a higher variability in response time than the patients who showed no change or a decreased cortisol level. The result of the current study suggests that stress-induced high norepinephrine (NE) release may accompany poorer attention performance in patients with ADHD.

Association between attention-deficit/hyperactivity disorder and epilepsy in pediatric populations

There is a bidirectional relationship between attention-deficit/hyperactivity disorder (ADHD) and epilepsy. ADHD increases seizure risk, while patients with epilepsy have an increased prevalence of ADHD. The reasons explaining this association are not fully understood. Proposed mechanisms include effects of antiepileptic medications, underlying neurodevelopmental vulnerability, the effects of chronic seizures and subclinical epileptiform activity on cognitive functions and adrenergic dysfunction. There may also be a common genetic defect underlying both disorders in some families. Antiepileptics associated with ADHD-like side effects include phenobarbital, gabapentin, vigabatrin and topiramate. Methylphenidate has been studied in a double-blind setting against placebo for treatment of ADHD comorbid with epilepsy, and has a good risk-benefit ratio. Amphetamine, atomoxetine, clonidine and guanfacine only have case series to support their use and bupropion should be avoided.

Attention-deficit disorders and epilepsy in childhood: incidence, causative relations and treatment possibilities

At least 20% of children with epilepsy have clinical attention-deficit hyperactivity disorder (ADHD) compared to 3% to 7% of the general pediatric population. Several mechanisms may account for the high prevalence, such as a common genetic propensity, noradrenergic system dysregulation, subclinical epileptiform discharges, or even seizures, antiepileptic drug effects, and psychosocial factors. At the same time, children with attention-deficit hyperactivity disorder have a higher than normal rate of electroencephalography abnormalities (5.6-30.1% vs. 3.5%). Methylphenidate treatment is equally efficient in children with isolated attention-deficit hyperactivity disorder and in children with attention-deficit hyperactivity disorder and epilepsy (70%-77%). Electroencephalography screening in patients with attention-deficit hyperactivity disorder in the absence of other clinical indications or before starting methylphenidate treatment is not currently indicated. Methylphenidate is considered safe for use in children who are seizure-free. However, the few reports of seizure aggravation in methylphenidate-treated children with uncontrolled epilepsy have raised concern.

Avaliação da memória de trabalho em crianças com transtorno do déficit de atenção e hiperatividade

Esse projeto investigou as habilidades cognitivas da Memória de Trabalho de crianças e adolescentes com o “Transtorno do Déficit de Atenção e Hiperatividade” (TDAH). Foi aplicado teste TIHC - Teste Infantil de Habilidades Cognitivas informatizado, avaliando principalmente cinco habilidades cognitivas Raciocínio Indutivas (RI), Memória de Armazenamento Auditiva (MAA) e Visual e Memória de Trabalho Auditiva (MTA) e Visual (MTV) usando o modelo de Cattell-Horn-Carroll. O teste foi aplicado em 62 sujeitos sendo 32 com TDAH do Hospital das Clínicas-SEPIA-USP e 30 sujeitos controle “normal” do Ensino Fundamental da rede municipal de 1ª à 8ª séries com idades entre 7 e 15 anos, de ambos os sexos. As análises executadas indicaram a existência de diferenças em diversos aspectos relacionados à memória nos tipos peculiares de crianças com TDAH. Verificou-se que as crianças com TDAH obtiveram bom desempenho nas provas de memória visual em detrimento as provas de memória auditiva. A correlação dos resultados do TIHC verificara que o tempo de reação da prova de memória de armazenamento visual manteve uma correlação significativa com a prova de cálculo.

Urinary catecholamines in children with attention deficit hyperactivity disorder (ADHD): modulation by a polyphenolic extract from pine bark (pycnogenol)

Our study tested the hypothesis that treatment with a potent polyphenol complex not only reduces hyperactivity of children, but also catecholamine excretion and oxidative stress. Urine catecholamine concentrations were measured in attention deficit hyperactivity disorder (ADHD) children and healthy controls. ADHD children received either placebo (PL) or Pycnogenol (Pyc), a bioflavonoid extract from the pine bark, for one month. The study was performed in a randomized, double-blind, PL controlled design. Concentrations of catecholamines were higher in urine of ADHD patients compared to those of healthy children. Moreover, noradrenaline (NA) concentrations positively correlated with degree of hyperactivity of ADHD children. In ADHD patients, adrenaline (A) and NA concentrations positively correlated with plasma levels of oxidized glutathione. The treatment of ADHD children with Pyc caused decrease of dopamine (D) and trend of A and NA decrase and increased GSH/GSSG ratio. In conclusion, the data provide further evidence for the overactivity of the noradrenergic system in ADHD and demonstrate that A release may be increased, as well. Treatment of ADHD children with Pyc normalized catecholamine concentrations, leading to less hyperactivity, and, consequently, to reduced oxidative stress.

Supportive neurodevelopmental evidence for ADHD as a developmental disorder

A baby is dependent on its primary caregiver (hereafter referred to as 'mother') for its emotional regulation. The development of emotional self-regulation is dependent on the growth and myelinisation of connections between cortical (control) and limbic (emotion) structures in the infant brain. The subcortical sympathetic limbic system is dominant from birth, and it is only at 14-18 months of age that the parasympathetic cortical inhibitory part develops. The maturation of specifically the right orbitofrontal cortex, which dominates both the sympathetic and parasympathetic limbic systems, is essential for the regulation of emotion for the rest of an individual's life. Behavioral hyperactivity, impulsivity and inattention are considered normal for children in the early practising phase (10-14 months). This stage is characterised by sympathetic dominance stimulated by the ventral tegmental limbic circuit. We hypothesise that children with Attention Deficit Hyperactivity Disorder remain stuck in this phase, and accordingly do not enter the next stage of emotional development, i.e., the late practising period, in which the lateral tegmental limbic circuit, which stimulates the parasympathetic system develops. Parental reactions, which may contribute to this block in emotional development, include: largely ignoring their child, until the child does something the parent disapproves of, then scolding the child, without consoling the child again afterwards. This leads susceptible children to develop defensive hyperactivity and inattention in order to avoid a shame state they are unable to cope with. Implications for therapy are that caregivers should be taught firstly to give lots of positive attention to their child, and if necessary to scold, to console the child immediately afterwards. If this can be achieved consistently, the child will have the chance to develop their parasympathetic lateral limbic circuit, and eventually right orbitofrontal dominance over both limbic circuits, which translates into the ability to self-regulate their emotional states.

Sex differences in adolescent ADHD: findings from concurrent EEG and EDA

OBJECTIVE

Attention Deficit Hyperactivity Disorder (ADHD) occurs more frequently in male children and adolescents than in females, with a ratio of approximately 3 to 1. We determined whether psychophysiological differences are associated with the expression of ADHD in males and females, using simultaneously recorded electroencephalography (EEG) and electrodermal activity (EDA).

METHODS

Quantitative EEG and EDA measures were acquired simultaneously and continuously (2min) during an eyes closed resting condition for 70 ADHD adolescents (48 males, 22 females) and their age- and sex-matched controls.

RESULTS

Males and females with ADHD were differentiated by both EEG theta activity and EDA. ADHD males showed increased theta (widespread), whereas ADHD females showed a localised frontal enhancement of theta with reduced rate of EDA decrement. These sex differences were unrelated to ADHD subtype.

CONCLUSIONS

These findings suggest that different psychophysiological processes may underlie ADHD in each sex. The profile of theta enhancement in ADHD males is consistent with a developmental deviation model of ADHD, whereas ADHD in females may be better understood within an arousal model, which emphasizes both central and autonomic function.

SIGNIFICANCE

These findings highlight the potential for concurrent EDA measures to inform EEG studies of ADHD, particularly in regard to sex differences.

Mood and hormone responses to psychological challenge in adolescent males with conduct problems

BACKGROUND

Relations between stress hormones and antisocial behavior are understudied.

METHODS

A subsample (n = 335) of at-risk males recruited in first grade for a longitudinal study were recruited at approximately 16 years of age for a laboratory study, including two psychological challenges: describing their worst experience on videotape, and a task in which a loud tone could be avoided. Measures of affect, urine, and saliva were collected multiple times before and after challenges.

RESULTS

Negative affect increased following the worst-event challenge and decreased following the avoidance challenge. Mean conduct problems (CP) across ages 7-17 years were positively related to negative affect and inversely related to positive affect. CP were inversely related to post-challenge urinary epinephrine (E) levels when baseline E and potential confounds were controlled. Cortisol concentrations in saliva collected soon after the first challenge were positively related to CP in a post hoc subset of youths with extreme CP.

CONCLUSIONS

Key findings A) associated persistent CP with more negative affectivity and less positive affectivity, B) replicated and extended prior findings of an inverse association of CP and urinary E, and C) suggested provocative hypotheses for future study relating CP, trauma history, trauma recall, and cortisol reactivity.

Attachment and attention: protection in relation to gender and cumulative social-contextual adversity

Data from 918 children from the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care were examined to test the interrelation of attachment and attentional performance and 2 known risks for poor attentional performance: male gender and social-contextual adversity. Attachment was measured using the Strange Situation at 15 months, attentional performance by a Continuous Performance Test (CPT) and maternal questionnaires at 54 months, and social-contextual adversity by a variety of measures from birth to 54 months. Findings indicated (a) that children with secure attachment were less susceptible to the effects of cumulative risk and gender on CPT attentional performance than their insecure counterparts and that (b) no such differential risk susceptibility was evident for maternal reports of attention-related behavior problems.

Norepinephrine and acetylcholine mediation of the components of reflexive attention: implications for attention deficit disorders

Attention deficit hyperactivity disorders (ADHD) create major learning barriers for children and significant social and legal handicaps for adults worldwide. Important advances in the genetic basis of the disease have been made, but reliable, biological, diagnostic markers remain elusive. This review takes the position that future progress in treating the core symptom of attention deficits requires a clearer understanding of the neuroscience of attention in normal individuals. Two important achievements in this direction have been the development of tasks that identify activity in the orienting, alerting and conflict networks, and the identification of neurotransmitters that mediate these components. The proven ability of these tasks to identify and characterize response components of "normal" attention argues that they could be used advantageously with patient populations. The categorization of neurotransmitter abnormalities in those with ADHD could clarify whether attention deficits occur within or across attention networks. To realize these goals, we evaluate laboratory studies of attention in humans and animals that address the underlying neurotransmitter systems, primarily norepinephrine and acetylcholine. We propose that key facts about deficits in reflexive and voluntary attention may be understood by a model that includes deficits in brain norepinephrine release and its effects on cholinergic activity in the parietal cortex.

Sex differences in adult ADHD: a double dissociation in brain activity and autonomic arousal

It is now estimated that up to one-half of attention deficit hyperactivity disorder (ADHD) children continue to manifest symptoms in adulthood. A striking discrepancy between juvenile and adult populations is the increasing proportion of females with an ADHD diagnosis. To shed light on the psychophysiological mechanisms underlying adult ADHD, electroencephalography (EEG) and electrodermal index of arousal (skin conductance level or SCL) measures were employed under conditions of eyes-closed resting activity. Quantitative EEG (QEEG) and SCL were measured simultaneously and continuously (2 min) in 35 ADHD adults (21 males, 14 females) and their age- and sex-matched controls. As a group ADHD adults were found to have EEG and SCL deviations consistent with previous adolescent and juvenile studies. However, adult males (but not females) with ADHD showed increased EEG theta activity. By contrast, adult females (but not males) with ADHD were autonomically hypo-aroused (decreased SCL). These results suggest that distinct mechanisms may underpin adult ADHD in males and females.

Catecholamine functioning in children with traumatic brain injuries and children with attention-deficit/hyperactivity disorder

Recent studies suggest that children with attention-deficit/hyperactivity disorder (ADHD) and children with traumatic brain injuries (TBI) show changes in similar neuronal networks, including the dopaminergic (DA) and norepinephrinergic (NA) systems. Therefore, indirect measures of catecholamine activity were assessed. Twenty-six children with TBI, 31 children with ADHD, and 26 normal controls, 8 to 12 years of age, were investigated with a 90-min cognitive test battery. Before and after the tests, urine samples were collected to measure catecholamine activity in response to cognitive stress. Spontaneous eyeblinking as an indirect measure of DA activity was counted. Children with TBI and ADHD excreted significantly more normetanephrine in resting situations and less epinephrine (EPI) after cognitive stress, and showed a decreased blink rate compared to normal controls. Children with TBI also showed a higher excretion of metanephrine in the resting situation in comparison to children with ADHD and controls. Whereas children with ADHD showed a higher tonic activity of the NA system and a less adaptive EPI excretion in response to cognitive stress, children with TBI seem to be additionally impaired in their tonic EPI excretion. Our study provides further support for similar but also different neurobiochemical characteristics in both groups.

Catecholamine response to exercise in children with attention deficit hyperactivity disorder

The objective of this study was to examine differences in catecholamine (CA) response to exercise between children who had received a diagnosis of attention-deficit/hyperactivity disorder (ADHD) and age- and gender-matched controls. On the basis of the notion of a CA dysfunction in ADHD, we reasoned that the normal robust increase in circulating CA seen in response to exercise would be blunted in children with ADHD. To test this, we recruited 10 treatment-naïve children with newly diagnosed ADHD and 8 age-matched controls (all male) and measured CA response to an exercise test in which the work was scaled to each subject's physical capability. After exercise, epinephrine and norepinephrine increased in both control and ADHD subjects (p = 0.006 and p = 0.002, respectively), but the responses were substantially blunted in the ADHD group (p = 0.018) even though the work performed did not differ from controls. Circulating dopamine increased significantly in the control subjects (p < 0.016), but no increase was noted in the subjects with ADHD. Finally, a significant attenuation in the lactate response to exercise was found in ADHD (between groups, p < 0.005). Our data suggest that CA excretion after exercise challenges in children with ADHD is deficient. This deficiency can be detected using a minimally invasive, nonpharmacologic challenge.