Autonomic hypoactivity in boys with attention-deficit/hyperactivity disorder and the influence of methylphenidate

Long-term cortisol secretion in attention deficit hyperactivity disorder: roles of sex, comorbidity, and symptom presentation

Low activity of the hypothalamic-pituitary-adrenal axis (HPAA) has been found in children with attention deficit hyperactivity disorder (ADHD). The condition may be related to the reduced attention regulation capacity and/or to comorbid oppositional defiant or conduct disorder (ODD/CD). Sex differences are probable but not sufficiently studied. We analyzed the HPAA activity and sympathetic nervous system reactivity (SR) in children with ADHD while accounting for ADHD symptom presentation, comorbidity, and sex differences. The sample comprised 205 children, 98 (61 boys, 37 girls) with ADHD and 107 (48 boys, 59 girls) healthy controls. DSM-5 phenotypic symptom presentation and comorbid ODD/CD were assessed using clinical interviews. Hair cortisol concentration (HCC) was used to assess the long-term, cumulative activity of the HPAA. SR was assessed via skin conductance response (SCR). For control purposes, comorbid internalizing symptoms and indicators of adverse childhood experiences (ACE) were assessed. Children were medication naive. Boys presenting with predominantly inattentive symptoms (ADHD-I) showed lower HCC than healthy boys. Girls presenting with combined symptoms (ADHD-C) showed higher HCC than did healthy girls (p's < 0.05, sex-by-group interaction, F (2,194) = 4.09, p = 0.018). Boys with ADHD plus ODD/CD showed a blunted SR (p < 0.001, sex-by-group interaction, F (2,172) = 3.08, p = 0.048). Adjustment for ACE indicators led to non-significant differences in HCC but did not affect differences in SR. HCC constitutes an easily assessable, reliable, and valid marker of phenotypic ADHD-related features (i.e. symptom presentation and comorbidity). It indicates more homogenous subgroups of ADHD and might point to specifically involved pathophysiological processes.

An Individualized, Data-Driven Biological Approach to Attention-Deficit/Hyperactivity Disorder (ADHD) Heterogeneity

Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed mental health disorder in childhood, however, there is well-established heterogeneity in both the presentation of ADHD symptoms and secondary characteristics across the literature. Existing Diagnostic and Statistical Manual of Mental Disorders (DSM-5) nosology has been ineffective in explaining such heterogeneity in terms of both pathophysiology and clinical trajectories. The current study investigated ADHD heterogeneity via a biologically-based, data-driven approach (k-Means algorithm). Specifically, unique biological profiles (derived from patterns of parasympathetic and sympathetic functioning) were identified and utilized as predictors of clinical presentations. Two hundred eighty-nine participants (167 youth with ADHD), ages 5 to 13 years, completed an emotion-based task while indexes of parasympathetic (i.e., respiratory sinus arrhythmia [RSA]) and sympathetic (i.e., electrodermal activity [EDA]) activity were obtained. Overall, results suggest that three distinct biological profiles among youth with ADHD are evident, with biological profiles differing in regulation and arousal levels during emotionally evocative contexts: (Profile 1) underregulated, hyperaroused (negative contexts only), (Profile 2) typically regulated, underaroused, and (Profile 3) overregulated (positive contexts only), hyperaroused. Results are supported by several dopaminergic- and reward-based theories, integrating differing concepts across the literature, and adds biological support for existing models. Behaviorally, results may translate into differing clinical presentations, however, further work is needed. In general, youth with ADHD are heterogenous in autonomic functioning, which could have implications for synthesizing across differing theories within the literature, predicting clinical presentations, and developing targeted treatments.

Dysregulation of the autonomic nervous system in adult attention deficit hyperactivity disorder. A systematic review

Background: Adult Attention Deficit Hyperactivity Disorder (aADHD) is characterised by inattention, hyperactivity, impulsivity, and emotional instability, all of which were linked to altered modulation of the autonomic nervous system. This and the clinical effectiveness of sympathomimetic medication raised the question if autonomic modulation is altered in aADHD patients.Methods: We systematically searched PubMed, Cochrane Library, and Web Of Science for publications investigating autonomic modulation in aADHD and controls during resting-state and/or under task conditions.Results: We reviewed 15 studies involving 846 participants (424 aADHD and 422 controls), including 4 studies on sympathetic tone at rest, 13 studies on sympathetic modulation during tasks, 3 studies on resting state parasympathetic modulation and 3 papers on task-related parasympathetic modulation. Studies comprised measurements of electrodermal activity, heart rate variability, blood pressure variability, blood volume pulse, pre-ejection period, and baroreflex sensitivity. 2 studies reported reduced sympathetic tone in aADHD; 7 papers described lower sympathetic reactivity to task demands in this cohort. One study linked aADHD to impaired vagal tone, while no indications of altered tasks-related parasympathetic reactivity in aADHD patients were reported.Conclusion: The reviewed data revealed impaired cardiovascular autonomic modulation in aADHD patients, predominantly in sympathetic modulation and during stress exposure.

Methylphenidate Improves Autonomic Functioning among Youth with Attention-Deficit/Hyperactivity Disorder

Psychostimulants are commonly prescribed medications for youth with attention-deficit/hyperactivity disorder (ADHD). Limited studies have evaluated how psychostimulants (e.g., methylphenidate [MPH]) impact autonomic nervous system (ANS) indexes among youth with ADHD. Understanding the effects of MPH on autonomic functioning is essential, given that youth with ADHD have been shown to experience atypical autonomic functioning (i.e., reduced activity across both sympathetic and parasympathetic branches) compared to typically developing youth. The current study investigated how a specific psychostimulant, Osmotic Release Oral System [OROS] MPH, impacts parasympathetic (indexed by respiratory sinus arrhythmia [RSA]) and sympathetic (indexed by electrodermal activity [EDA]) functioning among youth with ADHD via a within-subjects, double-masked, cross-over design. Two hundred fifty-six participants (157 youth with ADHD), ages 5 to 13 years, completed a two-minute resting baseline task while electrocardiograph and electrodermal data were obtained. Youth with ADHD completed the resting baseline task twice, 3 weeks apart, once during active medication and once during placebo conditions (counterbalanced). Typically developing youth were assessed without medication or placebo. Youth with ADHD during the placebo condition exhibited reduced RSA and EDA compared to typically developing youth. In contrast, youth with ADHD during the medication condition did not differ significantly from typically developing youth with respect to either RSA nor EDA. As such, OROS MPH appears to normalize RSA and EDA levels among youth with ADHD to levels comparable to typically developing youth. Future studies including indexes of the ANS among youth with ADHD are urged to consider the impact of MPH.

Emotion Regulation via the Autonomic Nervous System in Children with Attention-Deficit/Hyperactivity Disorder (ADHD): Replication and Extension

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent disorder characterized by symptoms of inattention, hyperactivity, and/or impulsivity, as well as executive dysfunction. Recent work underlines the importance in understanding the role of emotion reactivity and regulatory deficits in the context of the disorder. One study (i.e., Musser et al. 2011) utilized a positive and negative emotion induction and suppression task, as well as indexes of autonomic nervous system reactivity, to examine emotional functioning in youth with ADHD. This study revealed inflexible parasympathetic-based regulation across emotion conditions among youth with ADHD compared to typically developing youth. The present study sought to replicate and extend these findings to a clinically recruited, diverse sample, while also examining sympathetic functioning. Two hundred fifty-nine participants (160 youth with ADHD), aged 5 to 13, completed the task utilized in Musser et al. 2011, while indexes of parasympathetic (i.e., respiratory sinus arrhythmia [RSA]) and sympathetic (i.e., pre-ejection period [PEP] and electrodermal activity [EDA]) reactivity were obtained. ADHD was associated with significantly elevated parasympathetic (i.e., augmented RSA) and sympathetic (as indexed by EDA) reactivity. Overall, results replicate and extend Musser et al. 2011, revealing sympathetic-linked disruptions in emotion reactivity and parasympathetic-linked disruptions in emotion regulation among youth with ADHD. Future studies of behavioral therapies for ADHD should consider the efficacy of adding an emotion regulation skills training component.

Reward-Related Dysfunctions in Children Developing Attention Deficit Hyperactivity Disorder-Roles of Oppositional and Callous-Unemotional Symptoms

Objectives: Neurocognitive functions might indicate specific pathways in developing attention deficit hyperactivity disorder (ADHD). We focus on reward-related dysfunctions and analyze whether reward-related inhibitory control (RRIC), approach motivation, and autonomic reactivity to reward-related stimuli are linked to developing ADHD, while accounting for comorbid symptoms of oppositional defiant disorder (ODD), and callous-unemotional (CU) traits. Methods: A sample of 198 preschool children (115 boys; age: m = 58, s = 6 months) was re-assessed at age 8 years (m = 101.4, s = 3.6 months). ADHD diagnosis was made by clinical interviews. We measured ODD symptoms and CU traits using a multi-informant approach, RRIC (Snack-Delay task, Gift-Bag task) and approach tendency using neuropsychological tasks, and autonomic reactivity via indices of electrodermal activity (EDA). Results: Low RRIC and low autonomic reactivity were uniquely associated with ADHD, while longitudinal and cross-sectional links between approach motivation and ADHD were completely explained by comorbid ODD and CU symptoms. Conclusion: High approach motivation indicated developing ADHD with ODD and CU problems, while low RRIC and low reward-related autonomic reactivity were linked to developing pure ADHD. The results are in line with models on neurocognitive subtypes in externalizing disorders.

Cognitive and Emotional Profiles of CU Traits and Disruptive Behavior in Adolescence: a Prospective Study

In this study we followed 82-90 adolescents, 50% boys, from 15 to 16 years, investigating CU traits and disruptive behaviors as predictors of cognitive skills and arousal to emotional pictures. At age 15, CU traits were rated by adolescents and disruptive (aggregated ADHD-ODD-delinquent) behaviors were rated by parents and adolescents. At age 16, executive function, reaction time variability (RTV), IQ and arousal to negative pictures were assessed. The results showed that, with control for disruptive behaviors, CU traits predicted lower RTV, higher IQ and lower arousal to negative pictures. With control for CU traits, disruptive behaviors predicted lower spatial working memory, lower interference control and higher RTV. Our findings are of theoretical and clinical relevance as they point to highly diverging cognitive and emotional profiles of CU traits and disruptive behaviors.

In Quest of Pathognomonic/Endophenotypic Markers of Attention Deficit Hyperactivity Disorder (ADHD): Potential of EEG-Based Frequency Analysis and ERPs to Better Detect, Prevent and Manage ADHD

Attention deficit hyperactivity disorder (ADHD) is a chronic heritable developmental delay psychiatric disorder requiring chronic management, characterized by inattention, hyperactivity, hyperkinectivity and impulsivity. Subjective clinical evaluation still remains crucial in its diagnosis. Discussed are two key aspects in the “characterizing ADHD” and on the quest for objective “pathognomonic/endophenotypic diagnostic markers of ADHD”. The first aspect briefly revolves around issues related to identification of pathognomonic/endophenotypic diagnostic markers in ADHD. Issues discussed include changes in ADHD definition, remission/persistence and overlapping-symptoms cum shared-heritability with its co-morbid cross-border mental disorders. The second aspect discussed is neurobiological and EEG-based studies on ADHD. Given the neurobiological and temporal aspects of ADHD symptoms the electroencephalograph (EEG) like NeuralScan by Medeia appears as an appropriate tool. The EEGs appropriateness is further enhanced when coupled with suitable behavior/cognitive/motor/psychological tasks/paradigms yielding EEG-based markers like event-related-potential (ERPs like P3 amplitudes and latency), reaction time variability (RTV), Theta:Beta ratio (TBR) and sensorimotor rhythm (SMR). At present, these markers could potentially help in the neurobiological characterization of ADHD and either help in identifying or lay the groundwork for identifying pathognomonic and/or endophenotypic EEG-based markers enabling its diagnosis, treatment and management.

Alexithymia as a Predictor of Arousal and Affect Dysregulations when Batterers with Attention Deficit Hyperactivity Disorder Cope with Acute Stress

Empirical research has stated that Attention Deficit Hyperactivity Disorder (ADHD) might underlie intimate partner violence against women (IPVAW) perpetration. Even though there is a clear relationship between these two variables, it is still unknown how ADHD facilitates violence proneness. In this regard, psychophysiological variables such as skin conductance levels (SCL) might offer information about emotional regulation when individuals cope with stress. Furthermore, alexithymia traits might be a strong candidate in explaining the above-mentioned emotional dysregulations. Hence, we compared the SCL response to acute cognitive stress in IPVAW perpetrators with and without ADHD symptoms to that of controls (non-violent and unaffected), and we also assessed the presence of alexithymia traits and their role in emotional regulation. Our data point out that ADHD IPVAW perpetrators presented higher SCL and negative affect than controls, particularly during the recovery period. Moreover, ADHD IPVAW perpetrators showed higher self-reported alexithymia, and this variable was a good predictor of autonomic and psychological state dysregulations, even after controlling for the effects of alcohol and drug misuse. Therefore, our study reinforces the need to consider psychophysiological measurements when screening the therapeutic needs of IPVAW perpetrators, due to their relatively low cost and the significant contents of their results. Finally, we also highlight the key role of alexithymia in this violent population, which should be considered when designing cognitive intervention training coadjutant to current psychotherapies for IPVAW perpetrators.

Acute blood pressure change with methylphenidate is associated with improvement in attention performance in children with ADHD

This exploratory study aims to determine whether the change in systolic blood pressure (sBP) after acute methylphenidate (MPH) administration (ΔBP_MPH) is associated with the neurocognitive response to MPH in the Conners Continuous Performance Test (CPT) in 513 children with ADHD (aged 6 to 12 years old). We noted that higher increases in sBP were associated with larger improvement in CPT performance with MPH. In the univariate regression model, the ΔBP_MPH accounted for an additional 2% of the variance in the change in CPT-Overall Index (OI) after controlling for covariates (p < .001). Linear regression analysis also indicated that ΔBP_MPH significantly contributed to predict a change in omission errors, reaction time, and reaction time variability (p < .001, p < .01, p = .001, respectively), but not in commission errors or detectability index (d`). Participants with a clinically meaningful sBP increase of at least 5 mmHg (n = 191) improved by 4.8 points on the CPT-OI score (p < .001), compared to an improvement of only 0.6 points for participants whose sBP declined by at least 5 mmHg (n = 121). In conclusion, larger sBP increases after MPH administration were associated with greater enhancement in CPT performance. These results could be useful in informing MPH dosing in clinical practice.

Decreased resting gamma activity in adult attention deficit/hyperactivity disorder

Objectives: To delineate task-free gamma activity in adult ADHD and healthy control subjects based on high-density EEG recordings. Relationship of gamma activity with symptom severity was also examined, since gamma activity is considered to be an index of network functions in the brain that underlie higher-order cognitive processes.Methods: Spontaneous EEG was recorded in adult ADHD subjects (N = 42; 25 methylphenidate-naïve and 17 on methylphenidate treatment) and controls (N = 59) with eyes open. EEG absolute power gamma was investigated in the gamma₁ (30.25-39 Hz) and gamma₂ (39.25-48 Hz) frequency bands.Results: Gamma₁ and gamma₂ activity was diminished in ADHD compared with healthy control subjects. The difference between ADHD and controls was the most pronounced in the right centroparietal region for both gamma₁ and gamma₂. Inverse associations were found between gamma₁ and gamma₂ activity and ADHD symptoms in centroparietal scalp regions.Conclusions: Gamma activity is reduced in adult ADHD, and the reduction has a predominantly right centroparietal distribution. Our findings are consistent with childhood ADHD literature with respect to diminished posterior gamma activity in patients, which may reflect altered dorsal attention network functions. Gamma abnormalities might provide a link between neurophysiological functioning and neuropsychological deficiencies, thereby offering an opportunity to investigate the neurobiological mechanisms that underlie the clinical symptoms of ADHD.

Brain arousal regulation and depressive symptomatology in adults with attention-deficit/hyperactivity disorder (ADHD)

BACKGROUND

The aim of the present study was to evaluate the stability of brain arousal in adult attention-deficit/hyperactivity disorder (ADHD) outpatients with and without depressive symptomatology, and its association with depressive symptom severity and absolute electroencephalogram (EEG) power in different frequency bands.

METHODS

We included 31 outpatient adults (45.16% females), who were diagnosed according to DSM-IV and received no medication. Their arousal stability score (index of the steepness of arousal decline during a 15-min EEG under resting conditions), the absolute EEG power and self-reports, including depressive and ADHD-related symptoms, were analyzed. Participants were split into an unstable and stable arousal group based on the median (= 6) of the arousal stability score.

RESULTS

ADHD patients in the stable group reported more severe depressive symptoms (p = 0.018) and showed reduced absolute EEG power in the delta (0.002 ≤ p ≤ 0.025) and theta (0.011 ≤ p ≤ 0.034) bands compared to those in the unstable group. There was no correlation between the arousal stability score and self-report-scales concerning ADHD-related symptoms (0.214 ≤ p ≤ 0.989), but a positive association with self-reported depressive severity (p = 0.018) and negative association with powers in the EEG delta and theta bands (0.001 ≤ p ≤ 0.033).

CONCLUSIONS

In view of high comorbidity of depression and ADHD in adult patients, these findings support the assumption that brain arousal regulation could be considered as a helpful marker for the clinical differentiation between ADHD and depression.

Viral rescue of magnocellular vasopressin cells in adolescent Brattleboro rats ameliorates diabetes insipidus, but not the hypoaroused phenotype

Dysregulated arousal often accompanies neurodevelopmental disorders such as attention deficit hyperactivity disorder and autism spectrum disorder. Recently, we have found that adolescent homozygous Brattleboro (Hom) rats, which contain a mutation in the arginine vasopressin (AVP) gene, exhibit lower behavioral arousal than their heterozygous (Het) littermates in the open field test. This hypoaroused phenotype could be due to loss of AVP in magnocellular cells that supply AVP to the peripheral circulation and project to limbic structures or parvocellular cells that regulate the stress axis and other central targets. Alternatively, hypoarousal could be a side effect of diabetes insipidus - polydipsia and polyuria seen in Hom rats due to loss of AVP facilitation of water reabsorption in the kidney. We developed a viral-rescue approach to "cure" magnocellular AVP cells of their Brattleboro mutation. Infusion of a recombinant adeno-associated virus (rAAV) containing a functional Avp gene and promoter (rAAV-AVP) rescued AVP within magnocellular cells and fiber projections of the paraventricular nucleus of the hypothalamus (PVN) of male and female adolescent Hom rats. Furthermore, water intake was markedly reduced, ameliorating the symptoms of diabetes insipidus. In contrast, open field activity was unaffected. These findings indicate that the hyporaoused phenotype of adolescent Hom rats is not due to the loss of AVP function in magnocellular cells or a side effect of diabetes insipidus, but favors the hypothesis that central, parvocellular AVP mechanisms underlie the regulation of arousal during adolescence.

Autonomic arousal profiles in adolescents and young adults with ADHD as a function of recording context

A recent study (James et al. 2016) found that attention-deficit/hyperactivity disorder (ADHD) was associated with hypo-arousal, indexed by low electrodermal activity, during a low-demand reaction-time task, which normalized in a fast-incentive condition. We now investigate if (1) autonomic arousal in individuals with ADHD changes over a long testing session and (2) across time, to clarify if arousal profiles are context-dependent. We also examine (3) how autonomic arousal relates to each ADHD symptom domain, and specificity of arousal profiles to ADHD, by controlling for oppositional defiant/conduct disorder (ODD/CD) symptoms. Skin conductance level and non-specific fluctuations were measured during four successive resting-state and cognitive conditions (Resting-state time 1, Continuous Performance Task, Fast Task: Baseline and Fast-Incentive conditions, Resting-state time 2) from 71 adolescents/young adults with ADHD and 140 controls. Lower arousal was observed in individuals with ADHD only during a slow, low-demanding task, and more fluctuating arousal was observed towards the end of assessment. Both inattentive and hyperactive-impulsive symptoms were associated with arousal levels and fluctuations, independently from ODD/CD. Overall, we extend previous findings showing that under-arousal, but also fluctuating arousal, are context-specific rather than stable impairments in ADHD.

Methylphenidate for attention deficit hyperactivity disorder (ADHD) in children and adolescents - assessment of adverse events in non-randomised studies

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in childhood. The psychostimulant methylphenidate is the most frequently used medication to treat it. Several studies have investigated the benefits of methylphenidate, showing possible favourable effects on ADHD symptoms, but the true magnitude of the effect is unknown. Concerning adverse events associated with the treatment, our systematic review of randomised clinical trials (RCTs) demonstrated no increase in serious adverse events, but a high proportion of participants suffered a range of non-serious adverse events.

OBJECTIVES

To assess the adverse events associated with methylphenidate treatment for children and adolescents with ADHD in non-randomised studies.

SEARCH METHODS

In January 2016, we searched CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, 12 other databases and two trials registers. We also checked reference lists and contacted authors and pharmaceutical companies to identify additional studies.

SELECTION CRITERIA

We included non-randomised study designs. These comprised comparative and non-comparative cohort studies, patient-control studies, patient reports/series and cross-sectional studies of methylphenidate administered at any dosage or formulation. We also included methylphenidate groups from RCTs assessing methylphenidate versus other interventions for ADHD as well as data from follow-up periods in RCTs. Participants had to have an ADHD diagnosis (from the 3rd to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders or the 9th or 10th edition of theInternational Classification of Diseases, with or without comorbid diagnoses. We required that at least 75% of participants had a normal intellectual capacity (intelligence quotient of more than 70 points) and were aged below 20 years. We excluded studies that used another ADHD drug as a co-intervention.

DATA COLLECTION AND ANALYSIS

Fourteen review authors selected studies independently. Two review authors assessed risk of bias independently using the ROBINS-I tool for assessing risk of bias in non-randomised studies of interventions. All review authors extracted data. We defined serious adverse events according to the International Committee of Harmonization as any lethal, life-threatening or life-changing event. We considered all other adverse events to be non-serious adverse events and conducted meta-analyses of data from comparative studies. We calculated meta-analytic estimates of prevalence from non-comparative cohorts studies and synthesised data from patient reports/series qualitatively. We investigated heterogeneity by conducting subgroup analyses, and we also conducted sensitivity analyses.

MAIN RESULTS

We included a total of 260 studies: 7 comparative cohort studies, 6 of which compared 968 patients who were exposed to methylphenidate to 166 controls, and 1 which assessed 1224 patients that were exposed or not exposed to methylphenidate during different time periods; 4 patient-control studies (53,192 exposed to methylphenidate and 19,906 controls); 177 non-comparative cohort studies (2,207,751 participants); 2 cross-sectional studies (96 participants) and 70 patient reports/series (206 participants). Participants' ages ranged from 3 years to 20 years. Risk of bias in the included comparative studies ranged from moderate to critical, with most studies showing critical risk of bias. We evaluated all non-comparative studies at critical risk of bias. The GRADE quality rating of the evidence was very low.Primary outcomesIn the comparative studies, methylphenidate increased the risk ratio (RR) of serious adverse events (RR 1.36, 95% confidence interval (CI) 1.17 to 1.57; 2 studies, 72,005 participants); any psychotic disorder (RR 1.36, 95% CI 1.17 to 1.57; 1 study, 71,771 participants); and arrhythmia (RR 1.61, 95% CI 1.48 to 1.74; 1 study, 1224 participants) compared to no intervention.In the non-comparative cohort studies, the proportion of participants on methylphenidate experiencing any serious adverse event was 1.20% (95% CI 0.70% to 2.00%; 50 studies, 162,422 participants). Withdrawal from methylphenidate due to any serious adverse events occurred in 1.20% (95% CI 0.60% to 2.30%; 7 studies, 1173 participants) and adverse events of unknown severity led to withdrawal in 7.30% of participants (95% CI 5.30% to 10.0%; 22 studies, 3708 participants).Secondary outcomesIn the comparative studies, methylphenidate, compared to no intervention, increased the RR of insomnia and sleep problems (RR 2.58, 95% CI 1.24 to 5.34; 3 studies, 425 participants) and decreased appetite (RR 15.06, 95% CI 2.12 to 106.83; 1 study, 335 participants).With non-comparative cohort studies, the proportion of participants on methylphenidate with any non-serious adverse events was 51.2% (95% CI 41.2% to 61.1%; 49 studies, 13,978 participants). These included difficulty falling asleep, 17.9% (95% CI 14.7% to 21.6%; 82 studies, 11,507 participants); headache, 14.4% (95% CI 11.3% to 18.3%; 90 studies, 13,469 participants); abdominal pain, 10.7% (95% CI 8.60% to 13.3%; 79 studies, 11,750 participants); and decreased appetite, 31.1% (95% CI 26.5% to 36.2%; 84 studies, 11,594 participants). Withdrawal of methylphenidate due to non-serious adverse events occurred in 6.20% (95% CI 4.80% to 7.90%; 37 studies, 7142 participants), and 16.2% were withdrawn for unknown reasons (95% CI 13.0% to 19.9%; 57 studies, 8340 participants).

AUTHORS' CONCLUSIONS

Our findings suggest that methylphenidate may be associated with a number of serious adverse events as well as a large number of non-serious adverse events in children and adolescents, which often lead to withdrawal of methylphenidate. Our certainty in the evidence is very low, and accordingly, it is not possible to accurately estimate the actual risk of adverse events. It might be higher than reported here.Given the possible association between methylphenidate and the adverse events identified, it may be important to identify people who are most susceptible to adverse events. To do this we must undertake large-scale, high-quality RCTs, along with studies aimed at identifying responders and non-responders.

How Anxious Do You Think I Am? Relationship Between State and Trait Anxiety in Children With and Without ASD During Social Tasks

Individuals with autism spectrum disorder (ASD) often exhibit increased anxiety, even in non-stressful situations. We investigate general anxiousness (anxiety trait) and responses to stressful situations (anxiety state) in 22 adolescents with ASD and 32 typically developing controls. We measured trait anxiety with standardized self- and parent-reported questionnaires. We used a Biopac system to capture state anxiety via skin conductance responses, mean heart rate and heart rate variability during high- and low-anxiety tasks. Results reveal higher trait anxiety in adolescents with ASD (p < 0.05) and no group difference in state anxiety. Increased parent-reported trait anxiety may predict decreased state anxiety during high-stress conditions. Together, these findings suggest that higher trait anxiety may result in dampened physical responses to stress.

Developmental changes in autonomic responses are associated with future reward/punishment expectations: A study of sympathetic skin responses in the Markov decision task

OBJECTIVE

Autonomic nervous system activity is recognized as a major component of emotional responses. Future reward/punishment expectations depend upon the process of decision making in the frontal lobe, which is considered to play an important role in executive function. The aim of this study was to investigate the relationship between autonomic responses and decision making during reinforcement tasks using sympathetic skin responses (SSR).

METHODS

Nine adult and 9 juvenile (mean age, 10.2years) volunteers were enrolled in this study. SSRs were measured during the Markov decision task (MDT), which is a reinforcement task. In this task, subjects must endure a small immediate loss to ultimately get a large reward. The subjects had to undergo three sets of tests and their scores in these tests were assessed and evaluated.

RESULTS

All adults showed gradually increasing scores for the MDT from the first to third set. As the trial progressed from the first to second set in adults, SSR appearance ratios remarkably increased for both punishment and reward expectations. In comparison with adults, children showed decreasing scores from the first to second set. There were no significant inter-target differences in the SSR appearance ratio in the first and second set in children. In the third set, the SSR appearance ratio for reward expectations was higher than that in the neutral condition.

CONCLUSIONS

In reinforcement tasks, such as MDT, autonomic responses play an important role in decision making. We assume that SSRs are elicited during efficient decision making tasks associated with future reward/punishment expectations, which demonstrates the importance of autonomic function. In contrast, in children around the age of 10years, the autonomic system does not react as an organized response specific to reward/punishment expectations. This suggests the immaturity of the future reward/punishment expectations process in children.

Clinical features and subjective/physiological responses to emotional stimuli in the presence of emotion dysregulation in attention-deficit hyperactivity disorder

INTRODUCTION

Emotion dysregulation (ED) has long been recognized in clinical descriptions of attention-deficit hyperactivity disorder (ADHD), but a renewed interest in ED has advanced research on the overlap between the two entities. Autonomic reactivity (AR) is a neurobiological correlate of emotion regulation; however, the association between ADHD and AR remains unclear. Our aim was to explore the clinical differences, AR, and subjective emotional responses to visual emotional stimuli in ADHD children with and without ED.

METHOD

School-aged ADHD children with (n = 28) and without (n = 20) ED, according to the definition of deficiency in emotional self-regulation (DESR), and healthy controls (n = 22) were interviewed by using the Schedule for Affective Disorders and Schizophrenia for School Aged Children-Present and Lifetime version (K-SADS-PL) to screen frequent psychopathologies for these ages. All subjects were evaluated with Child Behavior Checklist 6-18 (CBCL), the Strengths and Difficulties Questionnaire (SDQ), the McMaster Family Assessment Device (FAD), the School-Age Temperament Inventory (SATI), and Conners' Parent Rating Scale (CPRS-48), which were completed by parents. To evaluate emotional responses, the International Affective Picture System (IAPS) and the subjective and physiological responses (electrodermal activity and heart rate reactivity) to selected pictures were examined.

RESULTS

Regarding clinically distinctive features, the ADHD+ED group differed from the ADHD-ED and the control groups in terms of having higher temperamental negative reactivity, more oppositional/conduct problems, and lower prosocial behaviors. In the AR measures, children in the ADHD+ED group rated unpleasant stimuli as more negative, but they still had lower heart rate reactivity (HRR) than the ADHD-ED and control groups; moreover, unlike the two other groups, the ADHD+ED group showed no differences in HRR between different emotional stimuli.

CONCLUSION

The presented findings are unique in terms of their ability to clinically and physiologically differentiate between ADHD children with and without ED.

Modifiable Arousal in Attention-Deficit/Hyperactivity Disorder and Its Etiological Association With Fluctuating Reaction Times

Background

Cognitive theories of attention-deficit/hyperactivity disorder (ADHD) propose that high within-subject fluctuations of cognitive performance in ADHD, particularly reaction time (RT) variability (RTV), may reflect arousal dysregulation. However, direct evidence of arousal dysregulation and how it may account for fluctuating RTs in ADHD is limited. We used skin conductance (SC) as a measure of peripheral arousal and aimed to investigate its phenotypic and familial association with RTV in a large sample of ADHD and control sibling pairs.

Methods

Adolescents and young adults (N = 292), consisting of 73 participants with ADHD and their 75 siblings, and 72 controls and their 72 siblings, completed the baseline (slow, unrewarded) and fast-incentive conditions of a RT task, while SC was simultaneously recorded.

Results

A significant group-by-condition interaction emerged for SC level (SCL). Participants with ADHD had decreased SCL, compared with controls, in the baseline condition but not the fast-incentive condition. Baseline SCL was negatively associated with RTV, and multivariate model fitting demonstrated that the covariance of SCL with RTV, and of SCL with ADHD, was mostly explained by shared familial effects.

Conclusions

ADHD is associated with decreased, but modifiable, tonic peripheral arousal. A shared familial cause underlies the relationship between arousal and RTV and between arousal and ADHD. Given the malleability of SCL, if our findings are replicated, it warrants further exploration as a potential treatment target for ADHD.

Underarousal in Adult ADHD: How Are Peripheral and Cortical Arousal Related?

In children and adults with attention deficit/hyperactivity disorder (ADHD), a general slowing of spontaneous electroencephalographic (EEG) brain activity and a decrease of event-related potential amplitudes such as the contingent negative variation (CNV) are observed. Additionally, some studies have reported decreased skin conductance level (SCL) in this clinical population leading to the hypothesis of a peripheral hypoarousal, which may be a target of biofeedback treatment in addition to or instead of neurofeedback. To our knowledge, the relationship between SCL and CNV has not been simultaneously investigated in one experiment. Using the theoretical background of the hypoarousal model, this article aims to gain more insight into the differences and correlations of cortical (CNV) and peripheral (SCL) arousal in adults with ADHD. A sample of 23 adults with ADHD and 22 healthy controls underwent an auditory Go-NoGo task with simultaneous 22-channel EEG and SCL recordings. Reaction time (RT) and reaction time variability (RTV) were also measured to assess task performance. Significantly decreased CNV amplitude and significantly higher RTV were observed in the ADHD group, reflecting cortical underarousal and problems with sustained attention. No significant correlation between peripheral underarousal and cortical underarousal was observed in the ADHD group or the control group. The observed cortical underarousal reflected in the decreased CNV supports the notion of a reduced CNV amplitude as a possible biomarker for ADHD. However, the connection between cortical and peripheral arousal is not as clear as is suggested in previous research investigating both separately. Implications of these results for new treatment options for ADHD such as biofeedback are discussed.

Hyperactivity and sensation seeking as autoregulatory attempts to stabilize brain arousal in ADHD and mania?

Hypoarousal as indicated by skin conductance and electroencephalography (EEG) has been discussed as a pathogenetic factor in attention-deficit/hyperactivity disorder (ADHD). The aim of this paper was to review these arousal-related pathogenetic concepts and to present the more recently proposed vigilance regulation model of affective disorders and ADHD. The latter builds on methodological advances in classifying short EEG segments into vigilance stages (Vigilance Algorithm Leipzig, VIGALL), indicating different states of global brain function ("brain arousal"). VIGALL allows the objective assessment of vigilance regulation under defined conditions, e.g. how fast vigilance declines to lower vigilance stages associated with drowsiness during 15-20-min EEG recordings under resting conditions with eyes closed. According to the vigilance regulation model, the hyperactivity and sensation seeking observed in overtired children, ADHD and mania may be interpreted as an autoregulatory attempt to create a stimulating environment in order to stabilize vigilance. The unstable regulation of vigilance observed in both mania and ADHD may thus explain the attention deficits, which become especially prominent in monotonous sustained attention tasks. Among the arguments supporting the vigilance regulation model are the facts that destabilizing vigilance (e.g., via sleep deprivation) can trigger or exacerbate symptoms of ADHD or mania, whereas stabilizing vigilance (e.g., via psychostimulants, reducing sleep deficits) alleviates these symptoms. The potential antimanic effects of methylphenidate are presently being studied in an international randomized controlled trial. We propose vigilance regulation as a converging biomarker, which could be useful for identifying treatment responders to psychostimulants and forming pathophysiologically more homogeneous ADHD subgroups for research purposes.

New neurotechnologies for the diagnosis and modulation of brain dysfunctions

This is a major review article to acquaint psychologists with new neurotechnologies for the diagnosis and modulation of brain abnormalities. While psychometrics measures brain functions in terms of behavioral parameters, a recently emerged branch of neuroscience called neurometrics relies on measuring the electrophysiological parameters of brain functioning. There are two approaches in neurometrics. The first relies on the spectral characteristics of spontaneous electroencephalograms (EEG) and measures deviations from normality in EEG recorded in the resting state. The second approach relies on event-related potentials (ERPs) that measure the electrical responses of the brain to stimuli and actions in behavioral tasks. The present study reviews recent research on the application of ERPs for the discrimination of different types of brain dysfunction. Attention deficit-hyperactivity disorder (ADHD) is used as an example. It is shown that the diagnostic power of ERPs is enhanced by the recent emergence of new methods of analysis, such as independent component analysis (ICA) and low resolution electromagnetic tomography (LORETA).