Neurobiology of attention deficit/hyperactivity disorder

A state-of-the-art overview of candidate diagnostic biomarkers for Attention-deficit/hyperactivity disorder (ADHD)

INTRODUCTION

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental conditions and is highly heterogeneous in terms of symptom profile, associated cognitive deficits, comorbidities, and outcomes. Heterogeneity may also affect the ability to recognize and diagnose this condition. The diagnosis of ADHD is primarily clinical but there are increasing research efforts aiming at identifying biomarkers that can aid the diagnosis.

AREAS COVERED

We first discuss the definition of biomarkers and the necessary research steps from discovery to implementation. We then provide a broad overview of research studies on candidate diagnostic biomarkers in ADHD encompassing genetic/epigenetic, biochemical, neuroimaging, neurophysiological and neuropsychological techniques. Finally, we critically appraise current limitations in the field and suggest possible ways forward.

EXPERT OPINION

Despite the large number of studies and variety of techniques used, no promising biomarkers have been identified so far. Clinical and biological heterogeneity as well as methodological limitations, including small sample size, lack of standardization, confounding factors, and poor replicability, have hampered progress in the field. Going forward, increased international collaborative efforts are warranted to support larger and more robustly designed studies, develop multimodal datasets to combine biomarkers and improve diagnostic accuracy, and ensure reproducibility and meaningful clinical translation.

Treatments and regulatory mechanisms of acoustic stimuli on mood disorders and neurological diseases

Acoustic stimuli such as music or ambient noise can significantly affect physiological and psychological health in humans. We here summarize positive effects of music therapy in premature infant distress regulation, performance enhancement, sleep quality control, and treatment of mental disorders. Specifically, music therapy exhibits promising effects on treatment of neurological disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). We also highlight regulatory mechanisms by which auditory intervention affects an organism, encompassing modulation of immune responses, gene expression, neurotransmitter regulation and neural circuitry. As a safe, cost-effective and non-invasive intervention, music therapy offers substantial potential in treating a variety of neurological conditions.

Exposures during pregnancy and at birth are associated with the risk of offspring eating disorders

BACKGROUND

Eating disorders (ED) are severe psychiatric disorders, commonly debuting early. Aberrances in the intrauterine environment and at birth have been associated with risk of ED. Here, we explore if, and at what effect size, a variety of such exposures associate with offspring ED, that is, anorexia nervosa (AN), bulimia nervosa (BN), and eating disorder not otherwise specified (EDNOS).

METHODS

This population-based cohort study, conducted from September 2021 to August 2023, used Finnish national registries of all live births in 1996-2014 (N = 1,097,753). Cox proportional hazards modeling was used to compare ED risk in exposed versus unexposed offspring, adjusting for potential confounders and performing sex-stratified analyses.

RESULTS

A total of 6614 offspring were diagnosed with an ED; 3668 AN, 666 BN, and 4248 EDNOS. Lower risk of offspring AN was seen with young mothers, continued smoking, and instrumental delivery, while higher risk was seen with older mothers, inflammatory disorders, prematurity, small for gestational age, and low Apgar. Offspring risk of BN was higher with continued smoking and prematurity, while lower with postmature birth. Offspring risk of EDNOS was lower with instrumental delivery, higher for older mothers, polycystic ovary syndrome, insulin-treated pregestational diabetes, antibacterial treatment, prematurity, and small for gestational age. Sex-specific associations were found.

CONCLUSIONS

Several prenatal and at birth exposures are associated with offspring ED; however, we cannot exclude confounding by maternal BMI. Nevertheless, several exposures selectively associate with risk of either AN, BN, or EDNOS, and some are sex-specific, emphasizing the importance of subtype- and sex-stratified analyses of ED.

PUBLIC SIGNIFICANCE

We define environmental factors involved in the development of different ED, of importance as preventive measure, but also in order to aid in defining the molecular pathways involved and thus in the longer perspective contribute to the development of pharmacological treatment of ED.

l-Arginine/nitric oxide pathway and oxidative stress in adults with ADHD: Effects of methylphenidate treatment

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) is a mental disorder that was once thought to occur only in children. Meanwhile, it is known that adults can also be affected. The first-line drug in children and adults to treat symptoms of inattention, impulsivity, lack of self-regulation, and hyperactivity is methylphenidate (MPH). Known adverse effects of MPH include cardiovascular problems, such as elevated blood pressure and heart rate. Therefore, biomarkers to monitor potential cardiovascular side effects of MPH are needed. The l-Arginine/Nitric oxide (Arg/NO) pathway is involved in noradrenaline and dopamine release as well as in normal cardiovascular functioning and is therefore a prime candidate for the search of biomarkers. The aim of the present study was to investigate the Arg/NO pathway as well as oxidative stress in adult ADHD patients in plasma and urine and the potential influence of MPH medication.

METHODS

In plasma and urine samples of 29 adults with ADHD (39.2 ± 10.9 years) and 32 healthy adults serving as controls (CO) (38.0 ± 11.6 years) the major NO metabolites nitrite and nitrate, Arg, the NO synthesis inhibitor asymmetric dimethylarginine (ADMA) and its major urinary metabolite dimethylamine (DMA) as well as malondialdehyde (MDA) were measured by gas chromatography-mass spectrometry.

RESULTS

Of the 29 patients with ADHD 14 were currently without MPH treatment (-MPH) and 15 were treated with MPH (+MPH). Plasma nitrate concentrations were significantly higher in patients not treated with MPH vs. CO (-MPH 60.3 μM [46.2-76.0] vs. CO 44.4 μM [35.0-52.7]; p = 0.002), while plasma nitrite tended to be higher in -MPH patients (2.77 μM [2.26-3.27]) vs. CO (2.13 μM [1.50-2.93]; p = 0.053). Additionally, plasma creatinine concentrations were significantly different, with -MPH showing significantly higher concentrations than the other two groups (-MPH 141 μM [128-159]; +MPH 96.2 μM [70.2-140]; Co 75.9 μM [62.0-94.7]; p < 0.001). Urinary creatinine excretion tended to be lowest in -MPH group vs. +MPH and CO (-MPH 11.4 ± 8.88 mM; +MPH 20.7 ± 9.82 mM; 16.6 ± 7.82 mM; p = 0.076). None of the other metabolites, including MDA, a marker of oxidative stress, showed a difference between the groups.

CONCLUSION

Adult patients with ADHD, who are not treated with MPH (-MPH), showed varied Arg/NO pathway, but Arg bioavailability seemed to be consistent over the groups. Our findings imply that urinary reabsorption may be increase and/or excretion of nitrite and nitrate may be decreased in ADHD, resulting in an increase in the plasma concentration of nitrite. MPH seems to partially reverse these effects by not yet known mechanisms, and does not affect oxidative stress.

Safety profiles of methylphenidate, amphetamine, and atomoxetine: analysis of spontaneous reports submitted to the food and drug administration adverse event reporting system

Background: Methylphenidate, atomoxetine, and Amphetamine are the three most commonly used medications approved by the United States Food and Drug Administration (FDA) for the treatment of attention deficit/hyperactivity disorder (ADHD). However, a comprehensive analysis of their safety profiles across various age groups and genders in real-world contexts has yet to be conducted. In this study, a pharmacovigilance analysis was performed using the FDA Adverse Event Reporting System (FAERS) database to examine differences in adverse events between methylphenidate, atomoxetine, and Amphetamine. Methods: From January 2014 to September 2022, FAERS reports listing "Methylphenidate," "Dexmethylphenidate," "Atomoxetine," "Amphetamine," "Lisdexamfetamine," "Dextroamphetamine," and "Methamphetamine" as primary suspects were analyzed after removing duplicate reports. We used the standardized Medical Dictionary for Regulatory Activities (MedDRA) query generalized search for adverse events at the preferred term level based on case reports. After filtering duplicate reports, disproportionality analysis was used to detect safety signals according to the proportional reporting ratio (PRR). In order to delve into potential safety concerns, we undertook a two-step analysis of the data. Initially, the data was segmented based on age cohorts: 0-5 years, 6-12 years, 13-18 years, and individuals aged ≥19 years. Following this, after partitioning the data into males and females within the 0-18 years age group, and similarly for those aged ≥19 years, further analysis was conducted. Results: The pharmacovigilance analysis uncovered substantial safety signals in the standardized MedDRA queries. Methylphenidate was associated with dyskinesia (PRR = 21.15), myocardial infarction (PRR = 12.32), and hypertension (PRR = 8.95) in children aged 0-5, 6-12, and 13-18 years, respectively, as well as neonatal exposures via breast milk (PRR = 14.10) in adults aged ≥19 years. Atomoxetine was linked to hostility/aggression (PRR = 15.77), taste and smell disorders (PRR = 6.75), and hostility/aggression (PRR = 6.74) in children aged 0-5, 6-12, and 13-18 years, respectively, as well as hostility/aggression (PRR = 14.00) in adults aged ≥19 years. Amphetamine was associated with psychosis and psychotic disorders (PRR = 16.78), hostility/aggression (PRR = 4.39), and Other ischaemic heart disease (PRR = 10.77) in children aged 0-5 years, 6-12 years, and 13-18 years, respectively, and hostility/aggression in adults aged ≥19 years (PRR = 9.16). Significant and noteworthy adverse event signals were also identified at the preferred term level. Specifically, methylphenidate was associated with myocardial infarction, acute myocardial infarction, coronary artery dissection, electrocardiogram QT prolonged, growth retardation, self-destructive behavior, suicidal ideation, and completed suicide. Atomoxetine was linked to electrocardiogram QT prolonged, growth retardation, and tic. Amphetamine was recorded for coronary artery dissection, suicidal ideation, and completed suicide. It was observed that male patients, including both children and adults, showed a more significant and frequent occurrence of adverse events compared to females, particularly in terms of cardiac disorders. The intensity and quantity of adverse event signals were distinctly different between the two genders, with males having a higher number of signals. All detected safety signals were confirmed using signals obtained from the disproportionality analysis. Conclusion: This pharmacovigilance analysis demonstrated significant variations in the safety profiles of methylphenidate, atomoxetine, and Amphetamine across different age groups and between different genders. Following an in-depth analysis of the FAERS database, we discerned prominent safety signals. Notably, the strength of the signals associated with coronary artery dissection induced by methylphenidate and amphetamine, as well as those related to suicide, demand particular attention. Consequently, it remains imperative to persist in monitoring these medications, assessing the associated risks, and carrying out comparative studies particularly geared towards ADHD drugs.

Agomelatine: A Potential Multitarget Compound for Neurodevelopmental Disorders

Agomelatine (AGM) is one of the latest atypical antidepressants, prescribed exclusively for the treatment of depression in adults. AGM belongs to the pharmaceutical class of melatonin agonist and selective serotonin antagonist ("MASS"), as it acts both as a selective agonist of melatonin receptors MT1 and MT2, and as a selective antagonist of 5-HT2C/5-HT2B receptors. AGM is involved in the resynchronization of interrupted circadian rhythms, with beneficial effects on sleep patterns, while antagonism on serotonin receptors increases the availability of norepinephrine and dopamine in the prefrontal cortex, with an antidepressant and nootropic effect. The use of AGM in the pediatric population is limited by the scarcity of data. In addition, few studies and case reports have been published on the use of AGM in patients with attention deficit and hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Considering this evidence, the purpose of this review is to report the potential role of AGM in neurological developmental disorders. AGM would increase the expression of the cytoskeleton-associated protein (ARC) in the prefrontal cortex, with optimization of learning, long-term memory consolidation, and improved survival of neurons. Another important feature of AGM is the ability to modulate glutamatergic neurotransmission in regions associated with mood and cognition. With its synergistic activity a melatoninergic agonist and an antagonist of 5-HT2C, AGM acts as an antidepressant, psychostimulant, and promoter of neuronal plasticity, regulating cognitive symptoms, resynchronizing circadian rhythms in patients with autism, ADHD, anxiety, and depression. Given its good tolerability and good compliance, it could potentially be administered to adolescents and children.

Effects of music therapy as an alternative treatment on depression in children and adolescents with ADHD by activating serotonin and improving stress coping ability

OBJECTIVE

The objective of this study was to determine the effect of music therapy as an alternative treatment on depression in children and adolescents with attention-deficit hyperactivity disorder (ADHD) by activating serotonin (5-HT) and improving stress coping ability.

METHODS

This study is designed based on randomization method. A total of 36 subjects participated in the experiment, consisting of an ADHD control group (n = 18) and ADHD music therapy group (n = 18). The ADHD control group received standard care, while the ADHD music therapy group received music therapy and standard care. The ADHD music therapy group received both active music therapy (improvisation) and receptive music therapy (music listening) for 50 minutes, twice a week, for 3 months: a total of 24 times. From a neurophysiological perspective, changes in depression and stress were tracked by measuring 5-HT secretion, cortisol expression, blood pressure (BP), heart rate (HR), and CDI and DHQ psychological scales.

RESULTS

The ADHD music therapy group's 5-HT secretion increased (p < 0.001), whereas cortisol expression (p < 0.001), BP (p < 0.001) and HR (p < 0.001) decreased. The CDI and DHQ psychological scales also showed positive changes (p < 0.01 and p < 0.001, respectively). However, the ADHD Con G's (who did not receive music therapy) 5-HT secretion did not increase, whereas cortisol expression, BP, and HR did not decrease. In addition, the CDI and DHQ psychological scales did not display positive changes.

CONCLUSIONS

In conclusion, the application of music therapy as an alternative treatment for ADHD children and adolescents showed positive neurophysiological and psychological effects. Therefore, this study would like to propose a new alternative to medicine for preventing and treating depression through various uses of music therapy.

Catecholaminergic and cholinergic neuromodulation in autism spectrum disorder: A comparison to attention-deficit hyperactivity disorder

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by social impairments and restricted, repetitive behaviors. Treatment of ASD is notoriously difficult and might benefit from identification of underlying mechanisms that overlap with those disturbed in other developmental disorders, for which treatment options are more obvious. One example of the latter is attention-deficit hyperactivity disorder (ADHD), given the efficacy of especially stimulants in treatment of ADHD. Deficiencies in catecholaminergic systems [dopamine (DA), norepinephrine (NE)] in ADHD are obvious targets for stimulant treatment. Recent findings suggest that dysfunction in catecholaminergic systems may also be a factor in at least a subgroup of ASD. In this review we scrutinize the evidence for catecholaminergic mechanisms underlying ASD symptoms, and also include in this analysis a third classic ascending arousing system, the acetylcholinergic (ACh) network. We complement this with a comprehensive review of DA-, NE-, and ACh-targeted interventions in ASD, and an exploratory search for potential treatment-response predictors (biomarkers) in ASD, genetically or otherwise. Based on this review and analysis we propose that (1) stimulant treatment may be a viable option for an ASD subcategory, possibly defined by genetic subtyping; (2) cerebellar dysfunction is pronounced for a relatively small ADHD subgroup but much more common in ASD and in both cases may point toward NE- or ACh-directed intervention; (3) deficiency of the cortical salience network is sizable in subgroups of both disorders, and biomarkers such as eye blink rate and pupillometric data may predict the efficacy of targeting this underlying deficiency via DA, NE, or ACh in both ASD and ADHD.

Adult ADHD: Underdiagnosis of a Treatable Condition

Attention-deficit/hyperactivity disorder is a common neurodevelopmental disorder, well-characterized within the pediatric population and representing one of the most prevalent mental conditions among children and adolescents. Once diagnosed, pharmacologic and psychosocial therapies can reduce symptomatic expression and functional impairment. Traditionally thought to resolve by young adulthood, it is now recognized that ADHD persists into adulthood. Many of these individuals were never evaluated for ADHD as children and remain undiagnosed as adults, continuing to struggle with symptoms. It is common to develop compensatory strategies geared at mitigating the disruptive effects of ADHD. In this article, we provide an overview of adult ADHD, review changes to DSM-5 diagnostic criteria meant to facilitate diagnosis of ADHD during adulthood, and discuss various factors that serve as barriers to accurate detection of adult ADHD.

A Potential Role for Neuroinflammation in ADHD

Attention deficit hyperactivity disorder (ADHD) is a neurobehavioural disorder in children and adolescents. Although increases in oxidative stress and disturbances of neurotransmitter system such as the dopaminergic and abnormalities in several brain regions have been demonstrated, the pathophysiology of ADHD is not fully understood. Nevertheless, ADHD involves several factors that have been associated with an increase in neuroinflammation. This chapter presents an overview of factors that may increase neuroinflammation and play a potential role in the development and pathophysiology of ADHD. The altered immune response, polymorphisms in inflammatory-related genes, ADHD comorbidity with autoimmune and inflammatory disorders and prenatal exposure to inflammation are associated with alterations in offspring brain development and are a risk factor; genetic and environmental risk factors that may increase the risk for ADHD and medications can increase neuroinflammation. Evidence of an association between these factors has been an invaluable tool for research on inflammation in ADHD. Therefore, evidence studies have made it possible to generate alternative therapeutic interventions using natural products as anti-inflammatories that could have great potential against neuroinflammation in ADHD.

Neuroprotection in late life attention-deficit/hyperactivity disorder: A review of pharmacotherapy and phenotype across the lifespan

For decades, psychostimulants have been the gold standard pharmaceutical treatment for attention-deficit/hyperactivity disorder (ADHD). In the United States, an astounding 9% of all boys and 4% of girls will be prescribed stimulant drugs at some point during their childhood. Recent meta-analyses have revealed that individuals with ADHD have reduced brain volume loss later in life (>60 y.o.) compared to the normal aging brain, which suggests that either ADHD or its treatment may be neuroprotective. Crucially, these neuroprotective effects were significant in brain regions (e.g., hippocampus, amygdala) where severe volume loss is linked to cognitive impairment and Alzheimer's disease. Historically, the ADHD diagnosis and its pharmacotherapy came about nearly simultaneously, making it difficult to evaluate their effects in isolation. Certain evidence suggests that psychostimulants may normalize structural brain changes typically observed in the ADHD brain. If ADHD itself is neuroprotective, perhaps exercising the brain, then psychostimulants may not be recommended across the lifespan. Alternatively, if stimulant drugs are neuroprotective, then this class of medications may warrant further investigation for their therapeutic effects. Here, we take a bottom-up holistic approach to review the psychopharmacology of ADHD in the context of recent models of attention. We suggest that future studies are greatly needed to better appreciate the interactions amongst an ADHD diagnosis, stimulant treatment across the lifespan, and structure-function alterations in the aging brain.

Slitrk2 deficiency causes hyperactivity with altered vestibular function and serotonergic dysregulation

SLITRK2 encodes a transmembrane protein that modulates neurite outgrowth and synaptic activities and is implicated in bipolar disorder. Here, we addressed its physiological roles in mice. In the brain, the Slitrk2 protein was strongly detected in the hippocampus, vestibulocerebellum, and precerebellar nuclei—the vestibular-cerebellar-brainstem neural network including pontine gray and tegmental reticular nucleus. Slitrk2 knockout (KO) mice exhibited increased locomotor activity in novel environments, antidepressant-like behaviors, enhanced vestibular function, and increased plasticity at mossy fiber–CA3 synapses with reduced sensitivity to serotonin. A serotonin metabolite was increased in the hippocampus and amygdala, and serotonergic neurons in the raphe nuclei were decreased in Slitrk2 KO mice. When KO mice were treated with methylphenidate, lithium, or fluoxetine, the mood stabilizer lithium showed a genotype-dependent effect. Taken together, Slitrk2 deficiency causes aberrant neural network activity, synaptic integrity, vestibular function, and serotonergic function, providing molecular-neurophysiological insight into the brain dysregulation in bipolar disorders.

•

Slitrk2 KO mice showed antidepressant-like behaviors and enhanced vestibular function

•

Mossy fiber-CA3 synaptic sensitivity to serotonin was reduced in Slitrk2 KO mice

•

Serotonin metabolite was increased in hippocampus and amygdala of Slitrk2 KO mice

•

Numbers of serotonergic neurons in raphe nuclei were decreased in Slitrk2 KO mice

The Pharmacokinetics and Pharmacogenomics of Psychostimulants

The psychostimulants-amphetamine and methylphenidate-have been in clinical use for well more than 60 years. In general, both stimulants are rapidly absorbed with relatively poor bioavailability and short half-lives. The pharmacokinetics of both stimulants are generally linear and dose proportional although substantial interindividual variability in pharmacokinetics is in evidence. Amphetamine (AMP) is highly metabolized by several oxidative enzymes forming multiple metabolites while methylphenidate (MPH) is primarily metabolized by hydrolysis to the inactive metabolite ritalinic acid. At present, pharmacogenomic testing as an aid to guide dosing and personalized treatment cannot be recommended for either agent. Few pharmacokinetically based drug-drug interactions (DDIs) have been documented for either stimulant.

Prenatal risk factors and genetic causes of ADHD in children

BACKGROUND

Attention deficit/hyperactivity disorder (ADHD) is a common disease among children; it affected 5-7% of the population in 2015. ADHD is a multifactorial disease, and its etiology is still not clearly understood.

DATA SOURCES

This narrative review has been done by searching the PubMed and Embase databases using attention deficit/hyperactivity disorder, ADHD, risk factors; genetics; pediatrics; psychiatrics as keywords.

RESULTS

ADHD is considered to be a hereditary disorder in which genes play the fundamental role in the pathogenesis; however, findings from genetic-environmental studies support the hypothesis that genetic factors can exert effects on an individual's condition by determining his/her responses to environmental exposures, especially those during the prenatal stage.

CONCLUSION

ADHD is considered as a hereditary disorder in which genes and prenatal risk factors play fundamental roles in the pathogenesis.

Modelling ADHD-Like Phenotypes in Zebrafish

The use of multiple species to model complex human psychiatric disorders, such as ADHD, can give important insights into conserved evolutionary patterns underlying multidomain behaviors (e.g., locomotion, attention, and impulsivity). Here we discuss the advantages and challenges in modelling ADHD-like phenotypes in zebrafish (Danio rerio), a vertebrate species that has been widely used in neuroscience and behavior research. Moreover, multiple behavioral tasks can be used to model the core symptoms of ADHD and its comorbidities. We present a critical review of current ADHD studies in zebrafish, and how this species might be used to accelerate the discovery of new drug treatments for this disorder.

Fast Tracking Assessment of Attention Deficit Hyperactivity Disorder in Tertiary Care

Current pediatric practice guidelines recommend children with complex attention deficit hyperactivity disorder (ADHD) receive a psychological evaluation. However, obtaining such an evaluation in a timely manner can be difficult. The authors present a framework for an economical, efficient, and efficacious approach to diagnosing complex ADHD based on a 5-year project to “fast track” these types of assessments in a tertiary care setting. Patients were triaged to the “fast track” for a streamlined assessment, by a psychologist, within a developmental pediatrics center. Assessment data, diagnoses, and recommendations were recorded for 79 participants. For most of the children, not only was ADHD confirmed, but diagnostic criteria were also met for at least one comorbid condition. For 64% of children the diagnostic picture changed, resulting in an ADHD diagnosis with corresponding changes to treatment planning. Fast track programming cut the wait time for evaluations in half. Preliminary data shows it is possible to clarify diagnoses for this complex population and provide much needed treatment recommendations in a timelier manner through utilization of a “fast track” approach to triage and assessment.

Association between methylphenidate and risk of myocardial infarction: A multinational self-controlled case series study

PURPOSE

To investigate the association between use of methylphenidate and risk of myocardial infarction among Asians.

METHODS

We conducted a multinational self-controlled case series study using nationwide healthcare databases of South Korea (2002-2018), Taiwan (2004-2015), and Hong Kong (2001-2016). Of patients with myocardial infarction who were also prescribed methylphenidate within the observation period, methylphenidate use was classified into four mutually exclusive periods by each person-day: exposed (exposed to methylphenidate), pre-exposure (prior to the first methylphenidate prescription), washout (after the end of methylphenidate treatment), and baseline (unexposed to methylphenidate). Risk of myocardial infarction among the three periods of methylphenidate use was compared to the baseline period using conditional Poisson regression analysis to estimate incidence rate ratios (IRRs) with 95% confidence intervals (CIs).

RESULTS

We identified 2104, 484, and 30 patients from South Korea, Taiwan, and Hong Kong, respectively. Risk of myocardial infarction was the highest during the pre-exposure period in all three populations: South Korea, pre-exposure (IRR 3.17, 95% CI 3.04-3.32), exposed (1.05, 1.00-1.11), washout (1.92, 1.80-2.04); Taiwan, pre-exposure (1.97, 1.78-2.17), exposed (0.72, 0.65-0.80), washout (0.56, 0.46-0.68); Hong Kong, pre-exposure (18.09, 8.19-39.96), exposed (9.32, 3.44-25.28), washout (7.69, 1.72-34.41). Following stratification for age and sex, the trends remained analogous to the main findings across all three populations.

CONCLUSIONS

Although a positive association between initiating methylphenidate and the onset of myocardial infarction was observed, the risk was the highest in the period before its initiation. Thus, this multinational study suggests there was no causal relationship between methylphenidate and myocardial infarction among Asians.

Scientific Practice in Modeling Diseases: Stances from Cancer Research and Neuropsychiatry

In the last few decades, philosophy of science has increasingly focused on multilevel models and causal mechanistic explanations to account for complex biological phenomena. On the one hand, biological and biomedical works make extensive use of mechanistic concepts; on the other hand, philosophers have analyzed an increasing range of examples taken from different domains in the life sciences to test-support or criticize-the adequacy of mechanistic accounts. The article highlights some challenges in the elaboration of mechanistic explanations with a focus on cancer research and neuropsychiatry. It jointly considers fields, which are usually dealt with separately, and keeps a close eye on scientific practice. The article has a twofold aim. First, it shows that identification of the explananda is a key issue when looking at dynamic processes and their implications in medical research and clinical practice. Second, it discusses the relevance of organizational accounts of mechanisms, and questions whether thorough self-sustaining mechanistic explanations can actually be provided when addressing cancer and psychiatric diseases. While acknowledging the merits of the wide ongoing debate on mechanistic models, the article challenges the mechanistic approach to explanation by discussing, in particular, explanatory and conceptual terms in the light of stances from medical cases.

SHR/NCrl rats as a model of ADHD can be discriminated from controls based on their brain, blood, or urine metabolomes

Attention-Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorder characterized by inattention, impulsivity, and hyperactivity. The neurobiological mechanisms underlying ADHD are still poorly understood, and its diagnosis remains difficult due to its heterogeneity. Metabolomics is a recent strategy for the holistic exploration of metabolism and is well suited for investigating the pathophysiology of diseases and finding molecular biomarkers. A few clinical metabolomic studies have been performed on peripheral samples from ADHD patients but are limited by their access to the brain. Here, we investigated the brain, blood, and urine metabolomes of SHR/NCrl vs WKY/NHsd rats to better understand the neurobiology and to find potential peripheral biomarkers underlying the ADHD-like phenotype of this animal model. We showed that SHR/NCrl rats can be differentiated from controls based on their brain, blood, and urine metabolomes. In the brain, SHR/NCrl rats displayed modifications in metabolic pathways related to energy metabolism and oxidative stress further supporting their importance in the pathophysiology of ADHD bringing news arguments in favor of the Neuroenergetic theory of ADHD. Besides, the peripheral metabolome of SHR/NCrl rats also shared more than half of these differences further supporting the importance of looking at multiple matrices to characterize a pathophysiological condition of an individual. This also stresses out the importance of investigating the peripheral energy and oxidative stress metabolic pathways in the search of biomarkers of ADHD.

Task-generic and task-specific connectivity modulations in the ADHD brain: an integrated analysis across multiple tasks

Attention-deficit/hyperactivity disorder (ADHD) is associated with altered functioning in multiple cognitive domains and neural networks. This paper offers an overarching biological perspective across these. We applied a novel strategy that extracts functional connectivity modulations in the brain across one (P_single), two (P_mix) or three (P_all) cognitive tasks and compared the pattern of modulations between participants with ADHD (n-89), unaffected siblings (n = 93) and controls (n = 84; total N = 266; age range = 8-27 years). Participants with ADHD had significantly fewer P_all connections (modulated regardless of task), but significantly more task-specific (P_single) connectivity modulations than the other groups. The amplitude of these P_single modulations was significantly higher in ADHD. Unaffected siblings showed a similar degree of P_all connectivity modulation as controls but a similar degree of P_single connectivity modulation as ADHD probands. P_all connections were strongly reproducible at the individual level in controls, but showed marked heterogeneity in both participants with ADHD and unaffected siblings. The pattern of reduced task-generic and increased task-specific connectivity modulations in ADHD may be interpreted as reflecting a less efficient functional brain architecture due to a reduction in the ability to generalise processing pathways across multiple cognitive domains. The higher amplitude of unique task-specific connectivity modulations in ADHD may index a more "effortful" coping strategy. Unaffected siblings displayed a task connectivity profile in between that of controls and ADHD probands, supporting an endophenotype view. Our approach provides a new perspective on the core neural underpinnings of ADHD.

Search for an epigenetic biomarker in ADHD diagnosis, based on the DAT1 gene 5'-UTR methylation: a new possible approach

Attention Deficit/Hyperactivity Disorder (ADHD) is the most common neuro-developmental alteration in childhood. To date, its diagnosis is exclusively clinical, however recent studies focused on searching for objective biomarkers. We recently reported a selective alteration of DNA methylation in the 5'-UTR of dopamine transporter (DAT1) gene, in a ¹CGG²CGG³CGG and a ⁵CG⁶CG motif, for ADHD patients (compared to controls). Presently, we looked for DNA methylation of the corresponding CpG sites but complementary on the opposite strand ("COS"). Exploiting a novel cross-correlation approach, we found a core M5 - M5 COS and M2 - M2 COS relationship with relatively free M1 and M6 COS extremes. Our data might be relevant, to find a new biomarker to diagnose ADHD in affected subjects.

Neurofibromatosis type 1: New developments in genetics and treatment

Neurofibromatosis type 1 is the most common neurocutaneous syndrome, with a frequency of 1 in 2500 persons. Diagnosis is paramount in the pretumor stage to provide proper anticipatory guidance for a number of neoplasms, both benign and malignant. Loss-of-function mutations in the NF1 gene result in truncated and nonfunctional production of neurofibromin, a tumor suppressor protein involved in downregulating the RAS signaling pathway. New therapeutic and preventive options include tyrosine kinase inhibitors, mTOR inhibitors, interferons, and radiofrequency therapy. This review summarizes recent updates in genetics, mutation analysis assays, and treatment options targeting aberrant genetic pathways. We also propose modified diagnostic criteria and provide an algorithm for surveillance of patients with neurofibromatosis type 1.

Caffeine Consumption plus Physical Exercise Improves Behavioral Impairments and Stimulates Neuroplasticity in Spontaneously Hypertensive Rats (SHR): an Animal Model of Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder (ADHD) is a prevalent and disabling disorder, mainly characterized by hyperactivity, inattention, and impulsivity, but also by olfactory and memory impairments that frequently persist throughout lifetime. The pathophysiology of ADHD is complex, involving several brain regions and neural pathways including alterations in adenosine neuromodulation. The administration of caffeine (a non-selective adenosine receptor antagonist) and physical exercise have been independently pointed as effective approaches for the management of ADHD symptoms. Here, we evaluated the effects of caffeine consumption (0.3 mg/mL in drinking water) plus physical exercise in running wheels during 6 weeks-starting during either adolescence (30 days old) or adulthood (4-5 months old)-on behavioral performance (including olfactory discrimination, open field, object recognition, and water maze tests) on the brain levels of monoamines (by high-performance liquid chromatography), on proteins related to synaptic plasticity and on brain-derived neurotrophic factor signaling (by Western blot analysis) in spontaneously hypertensive rats (SHRs), a validated animal model of ADHD. SHRs displayed persistent impairments of olfactory and short-term recognition memory from adolescence to adulthood, which were accompanied by lower levels of synaptosomal-associated protein 25 (SNAP-25) in the prefrontal cortex and hippocampus. The association of caffeine plus physical exercise during adolescence or adulthood restored the olfactory discrimination ability and, in an independent manner, improved short-term recognition memory of SHRs. These benefits were not associated to alterations in locomotor activity or in the hypertensive phenotype. The association of caffeine consumption plus physical exercise during adolescence increased the levels of SNAP-25, syntaxin, and serotonin in the hippocampus and prefrontal cortex, and striatal dopamine levels in SHRs. These results provide new evidence of the potential of caffeine and physical exercise, starting at adolescence or adult life, to improve behavioral impairments and stimulate neuroplasticity in ADHD.

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.

Independent Multiple Factor Association Analysis for Multiblock Data in Imaging Genetics

Multivariate methods have the potential to better capture complex relationships that may exist between different biological levels. Multiple Factor Analysis (MFA) is one of the most popular methods to obtain factor scores and measures of discrepancy between data sets. However, singular value decomposition in MFA is based on PCA, which is adequate only if the data is normally distributed, linear or stationary. In addition, including strongly correlated variables can overemphasize the contribution of the estimated components. In this work, we introduced a novel method referred as Independent Multifactorial Analysis (ICA-MFA) to derive relevant features from multiscale data. This method is an extended implementation of MFA, where the component value decomposition is based on Independent Component Analysis. In addition, ICA-MFA incorporates a predictive step based on an Independent Component Regression. We evaluated and compared the performance of ICA-MFA with both, the MFA method and traditional univariate analyses, in a simulation study. We showed how ICA-MFA explained up to 10-fold more variance than MFA and univariate methods. We applied the proposed algorithm in a study of 4057 individuals belonging to the population-based Rotterdam Study with available genetic and neuroimaging data, as well as information about executive cognitive functioning. Specifically, we used ICA-MFA to detect relevant genetic features related to structural brain regions, which in turn were involved, in the mechanisms of executive cognitive function. The proposed strategy makes it possible to determine the degree to which the whole set of genetic and/or neuroimaging markers contribute to the variability of the symptomatology jointly, rather than individually. While univariate results and MFA combinations only explained a limited proportion of variance (less than 2%), our method increased the explained variance (10%) and allowed the identification of significant components that maximize the variance explained in the model. The potential application of the ICA-MFA algorithm constitutes an important aspect of integrating multivariate multiscale data, specifically in the field of Neurogenetics.

Multivariate pattern classification on BOLD activation pattern induced by deep brain stimulation in motor, associative, and limbic brain networks

Deep brain stimulation (DBS) has been shown to be an effective treatment for movement disorders and it is now being extended to the treatment of psychiatric disorders. Functional magnetic resonance imaging (fMRI) studies indicate that DBS stimulation targets dependent brain network effects, in networks that respond to stimulation. Characterizing these patterns is crucial for linking DBS-induced therapeutic and adverse effects. Conventional DBS-fMRI, however, lacks the sensitivity needed for decoding multidimensional information such as spatially diffuse patterns. We report here on the use of a multivariate pattern analysis (MVPA) to demonstrate that stimulation of three DBS targets (STN, subthalamic nucleus; GPi, globus pallidus internus; NAc, nucleus accumbens) evoked a sufficiently distinctive blood-oxygen-level-dependent (BOLD) activation in swine brain. The findings indicate that STN and GPi evoke a similar motor network pattern, while NAc shows a districted associative and limbic pattern. The findings show that MVPA could be effectively applied to overlapping or sparse BOLD patterns which are often found in DBS. Future applications are expected employ MVPA fMRI to identify the proper stimulation target dependent brain circuitry for a DBS outcome.

A Randomized Controlled Trial of an Integrated Brain, Body, and Social Intervention for Children With ADHD

Objective: This study evaluated the efficacy of an Integrated Brain, Body, and Social (IBBS) intervention for children with ADHD. Treatment consisted of computerized cognitive remediation training, physical exercises, and a behavior management strategy. Method: Ninety-two children aged 5 to 9 years with ADHD were randomly assigned to 15 weeks of IBBS or to treatment-as-usual. Primary outcome measures included blinded clinician ratings of ADHD symptoms and global clinical functioning. Secondary outcome measures consisted of parent and teacher ratings of ADHD and neurocognitive tests. Results: No significant treatment effects were found on any of our primary outcome measures. In terms of secondary outcome measures, the IBBS group showed significant improvement on a verbal working memory task; however, this result did not survive correction for multiple group comparisons. Conclusion: These results suggest that expanding cognitive training to multiple domains by means of two training modalities does not lead to generalized improvement of ADHD symptomatology.

Optical dopamine monitoring with dLight1 reveals mesolimbic phenotypes in a mouse model of neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder whose neurodevelopmental symptoms include impaired executive function, attention, and spatial learning and could be due to perturbed mesolimbic dopaminergic circuitry. However, these circuits have never been directly assayed in vivo. We employed the genetically encoded optical dopamine sensor dLight1 to monitor dopaminergic neurotransmission in the ventral striatum of NF1 mice during motivated behavior. Additionally, we developed novel systemic AAV vectors to facilitate morphological reconstruction of dopaminergic populations in cleared tissue. We found that NF1 mice exhibit reduced spontaneous dopaminergic neurotransmission that was associated with excitation/inhibition imbalance in the ventral tegmental area and abnormal neuronal morphology. NF1 mice also had more robust dopaminergic and behavioral responses to salient visual stimuli, which were independent of learning, and rescued by optogenetic inhibition of non-dopaminergic neurons in the VTA. Overall, these studies provide a first in vivo characterization of dopaminergic circuit function in the context of NF1 and reveal novel pathophysiological mechanisms.

A systematic review of mindfulness based interventions for children and young people with ADHD and their parents

Objective

Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent disorders in childhood, which may pose risks in later life such as academic underachievement and anti-social behaviour. It has been suggested that mindfulness-based interventions (MBI) may contribute to positive outcomes with child and adult populations. In this article, we aim to systematically review the literature regarding the effectiveness of MBI on both children with ADHD and their parents.

Method

Seven databases were searched using the PRISMA criteria and included peer-reviewed journals and grey literature.

Results

Ten studies met the inclusion criteria. Findings suggested that MBI had positive results in addressing attention deficits in children with ADHD, but in terms of hyperactivity, the evidence was conflicting. MBI interventions also appear to effectively address parental stress and family functioning. However, the rating from the quality assessment showed several methodological limitations.

Discussion

The current evidence on the impact of MBI on ADHD symptoms is non-conclusive. However, promising data indicated the potential for MBI in addressing parental stress and family functioning. Further research is recommended to overcome the current methodological limitations.

A Neurodevelopmental Model of Combined Pyrethroid and Chronic Stress Exposure

Attention-deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders of childhood and previous studies indicate the dopamine system plays a major role in ADHD pathogenesis. Two environmental exposures independently associated with dopaminergic dysfunction and ADHD risk include exposure to deltamethrin, a pyrethroid insecticide, and chronic stress. We hypothesized that combined neurodevelopmental exposure to both deltamethrin and corticosterone (CORT), the major stress hormone in rodents, would result in additive changes within the dopamine system. To study this, we developed a novel dual exposure paradigm and exposed pregnant C57BL/6 dams to 3 mg/kg deltamethrin through gestation and weaning, and their offspring to 25 μg/mL CORT dissolved in the drinking water through adulthood. Midbrain RNA expression as well as striatal and cortical protein expression of key dopaminergic components were investigated, in addition to ADHD-like behavioral tasks and electrochemical dopamine dynamics via fast-scan cyclic voltammetry. Given the well-described sexual dimorphism of ADHD, males and females were assessed separately. Males exposed to deltamethrin had significantly decreased midbrain Pitx3 expression, decreased cortical tyrosine hydroxylase (TH) expression, increased activity in the Y maze, and increased dopamine uptake rate in the dorsal striatum. These effects did not occur in males exposed to CORT only, or in males exposed to both deltamethrin and CORT, suggesting that CORT may attenuate these effects. Additionally, deltamethrin- and CORT-exposed females did not display these dopaminergic features, which indicates these changes are sex-specific. Our results show dopaminergic changes from the RNA through the functional level. Moreover, these data illustrate the importance of testing multiple environmental exposures together to better understand how combined exposures that occur in certain vulnerable populations could affect similar neurodevelopmental systems, as well as the importance of studying sex differences of these alterations.

Sex and racial/ethnic differences in the association between childhood attention-deficit/hyperactivity disorder symptom subtypes and body mass index in the transition from adolescence to adulthood in the United States

BACKGROUND

While attention-deficit/hyperactivity disorder (ADHD) has been associated with higher body mass index (BMI), little research has focused on how this association differs by sex or race/ethnicity.

OBJECTIVE

To investigate the association between ADHD and BMI by sex and race/ethnicity (ie, European [EA], African [AA], and Hispanic American [HA]).

METHODS

Data came from the National Longitudinal Survey of Adolescent to Adult Health Waves II to IV (n = 13 332, age: 12-34 years). On the basis of self-reported childhood ADHD symptoms between the ages of 5 and 12 years, participants were categorized into: ADHD predominantly hyperactive/impulsive (ADHD-HI); ADHD predominantly inattentive (ADHD-I); ADHD combined (ADHD-C; a combination of ADHD-HI and ADHD-I symptoms); and non-ADHD.

RESULTS

The patterns of ADHD-BMI associations in the transition period between adolescence and young adulthood differed by sex and race/ethnicity. Compared with non-ADHD, ADHD-HI was associated with higher BMI among EA males and females, while ADHD-I was associated with higher BMI among EA females. ADHD-C was associated with higher BMI for HA females. We found no evidence of an association among AA males and females and HA males.

CONCLUSION

These study results suggest that the association between ADHD subtypes and BMI might differ across population subgroups in the United States.

Polygenic Risk and Neural Substrates of Attention-Deficit/Hyperactivity Disorder Symptoms in Youths With a History of Mild Traumatic Brain Injury

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a major sequela of traumatic brain injury (TBI) in youths. The objective of this study was to examine whether ADHD symptoms are differentially associated with genetic risk and brain structure in youths with and without a history of TBI.

METHODS

Medical history, ADHD symptoms, genetic data, and neuroimaging data were obtained from a community sample of youths. ADHD symptom severity was compared between those with and without TBI (TBI n = 418, no TBI n = 3193). The relationship of TBI history, genetic vulnerability, brain structure, and ADHD symptoms was examined by assessing 1) ADHD polygenic score (discovery sample ADHD n = 19,099, control sample n = 34,194), 2) basal ganglia volumes, and 3) fractional anisotropy in the corpus callosum and corona radiata.

RESULTS

Youths with TBI reported greater ADHD symptom severity compared with those without TBI. Polygenic score was positively associated with ADHD symptoms in youths without TBI but not in youths with TBI. The negative association between the caudate volume and ADHD symptoms was not moderated by a history of TBI. However, the relationship between ADHD symptoms and structure of the genu of the corpus callosum was negative in youths with TBI and positive in youths without TBI.

CONCLUSIONS

The identification of distinct ADHD etiology in youths with TBI provides neurobiological insight into the clinical heterogeneity in the disorder. Results indicate that genetic predisposition to ADHD does not increase the risk for ADHD symptoms associated with TBI. ADHD symptoms associated with TBI may be a result of a mechanical insult rather than neurodevelopmental factors.

Attention and executive functions computer training for attention-deficit/hyperactivity disorder (ADHD): results from a randomized, controlled trial

Multicenter randomized clinical superiority single-blind trial investigated the effect of a computer training program targeting multiple cognitive functions. Seventy children with ADHD, aged 6-13, were randomized to intervention or control group. The intervention group used ACTIVATE™ for 8 weeks and both groups received treatment as usual and were assessed in regard to cognitive functions, symptoms, behavioral and functional outcome measures after 8, 12 and 24 weeks. There was no significant effect on the primary outcome, sustained attention (β = - 0.047; CI - 0.247 to 0.153) or the secondary outcomes [parent-rated ADHD-RS, β = - 0.037; CI (- 0.224 to 0.150); teacher-rated-ADHD-RS, β = 0.093; CI (- 0.107 to 0.294); parent-rated-BRIEF, β = - 0.119; CI (- 0.307 to 0.069); and teacher-rated-BRIEF, β = 0.136; CI (- 0.048 to 0.322)]. This multicenter randomized clinical trial found no significant beneficial effects of cognitive training using the computer program ACTIVATE on the primary or secondary outcome measures in children with ADHD. Nevertheless, our study was likely underpowered to detect small to moderate changes.Trial registration ClinicalTrials.gov: NCT01752530, date of registration: December 10, 2012.

Is the Theta/Beta EEG Marker for ADHD Inherently Flawed?

OBJECTIVE

Despite advances in our understanding of ADHD as a neurodevelopmental disorder, robust biomarkers are yet to be established in clinical practice. More than 40 years of electroencephalography (EEG)-based research has culminated in the recent Food and Drug Administration (FDA) approval of the theta/beta (EEG power) ratio (TBR) as a diagnostic marker of ADHD.

METHOD

This review article focuses on resting-state EEG power research in ADHD.

RESULTS

Inconsistent findings in the literature and suggestions of reduced specificity threaten the utility of TBR as a biomarker of ADHD. The use of fixed EEG bands may be a significant limitation, particularly in youth, and alternative approaches are needed.

CONCLUSION

We propose that a personalized theta-to-alpha cut point or "transition frequency" is a better frame of reference for the measurement of TBR. Such an approach is better placed to test maturational lag and cortical hypoarousal models of ADHD and may in turn have greater utility in supporting diagnosis.

The Alpha-2A Adrenergic Receptor Gene -1291C/G Single Nucleotide Polymorphism is Associated with the Efficacy of Methylphenidate in Treating Taiwanese Children and Adolescents with Attention-Deficit Hyperactivity Disorder

OBJECTIVE

The therapeutic effect of methylphenidate (MPH) in treating attention-deficit/hyperactivity disorder (ADHD) has been related to the alpha-2A adrenergic receptor (ADRA2A) gene -1291C/G single nucleotide polymorphism (SNP). We investigated the effect of MPH in treating Taiwanese children and adolescent with ADHD and its relation to the ADRA2A gene -1291C/G SNP.

METHODS

The subjects with DSM-IV ADHD diagnosis underwent a titration period to find out the dose of MPH for maintenance treatment. After 4 weeks maintenance treatment, the effect of MPH was evaluated by the Swanson, Nolan and Pelham version IV total scores. The subjects with more than 25% score reduction were referred to responders and those with ≥50% improvement were considered as better responders. The -1291C/G variant of the ADRA2A gene was identified by DNA sequencing and what relevance it has to the MPH response was examined by binary logistic regression analysis.

RESULTS

Of the 59 subjects, 44 (74.6%) were responsive to MPH treatment and the responsiveness was not shown to be associated with the ADRA2A gene -1291C/G SNP. As the responsive subjects were categorized as moderate responders and better responders and subjected to statistical analysis, the GG homozygotes showed a greater chance to have a better response to MPH treatment than CC homozygotes (p=0.02), with an odds ratio of 32.14 (95% CI=1.64-627.80).

CONCLUSION

The ADRA2A gene -1291C/G SNP is associated with the efficacy of MPH for the treatment of ADHD in Taiwanese children and adolescents. The responsive subjects bearing homozygous -1291G allele are more likely to have a better response to MPH treatment.

The pharmacology of amphetamine and methylphenidate: Relevance to the neurobiology of attention-deficit/hyperactivity disorder and other psychiatric comorbidities

Psychostimulants, including amphetamines and methylphenidate, are first-line pharmacotherapies for individuals with attention-deficit/hyperactivity disorder (ADHD). This review aims to educate physicians regarding differences in pharmacology and mechanisms of action between amphetamine and methylphenidate, thus enhancing physician understanding of psychostimulants and their use in managing individuals with ADHD who may have comorbid psychiatric conditions. A systematic literature review of PubMed was conducted in April 2017, focusing on cellular- and brain system-level effects of amphetamine and methylphenidate. The primary pharmacologic effect of both amphetamine and methylphenidate is to increase central dopamine and norepinephrine activity, which impacts executive and attentional function. Amphetamine actions include dopamine and norepinephrine transporter inhibition, vesicular monoamine transporter 2 (VMAT-2) inhibition, and monoamine oxidase activity inhibition. Methylphenidate actions include dopamine and norepinephrine transporter inhibition, agonist activity at the serotonin type 1A receptor, and redistribution of the VMAT-2. There is also evidence for interactions with glutamate and opioid systems. Clinical implications of these actions in individuals with ADHD with comorbid depression, anxiety, substance use disorder, and sleep disturbances are discussed.

Potential for diagnosis versus therapy monitoring of attention deficit hyperactivity disorder: a new epigenetic biomarker interacting with both genotype and auto-immunity

In view of the need for easily accessible biomarkers, we evaluated in ADHD children the epigenetic status of the 5'-untranslated region (UTR) in the SLC6A3 gene, coding for human dopamine transporter (DAT). We analysed buccal swabs and sera from 30 children who met DSM-IV-TR criteria for ADHD, assigned to treatment according to severity. Methylation levels at six-selected CpG sites (among which, a CGGCGGCGG and a CGCG motif), alone or in combination with serum titers in auto-antibodies against dopamine transporter (DAT aAbs), were analysed for correlation with CGAS scores (by clinicians) and Conners' scales (by parents), collected at recruitment and after 6 weeks. In addition, we characterized the DAT genotype, i.e., the variable number tandem repeat (VNTR) polymorphisms at the 3'-UTR of the gene. DAT methylation levels were greatly reduced in ADHD patients compared to control, healthy children. Within patients carrying at least one DAT 9 allele (DAT 9/x), methylation at positions CpG2 and/or CpG6 correlated with recovery, as evident from delta-CGAS scores as well as delta Conners' scales ('inattentive' and 'hyperactive' subscales). Moreover, hypermethylation at CpG1 position denoted severity, specifically for those patients carrying a DAT 10/10 genotype. Intriguingly, high serum DAT-aAbs titers appeared to corroborate indications from high CpG1 versus high CpG2/CpG6 levels, likewise denoting severity versus recovery in DAT 10/10 versus 9/x patients, respectively. These profiles suggest that DAT 5'UTR epigenetics plus serum aAbs can serve as suitable biomarkers, to confirm ADHD diagnosis and/or to predict the efficacy of treatment.

The Effect of Experimental Supplementation with the Klamath Algae Extract Klamin on Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is a chronic neurobiological condition with onset in childhood. The disorder is characterized by inattention, impulsivity, and/or motor hyperactivity, which often affect the development and social integration of affected subjects. Phenylethylamine (PEA), naturally contained in the Klamath Lake microalgae and concentrated in the Klamin^® extract, is an endogenous molecule with a general neuromodulatory activity. It functions as an activator for the neurotransmission of dopamine and other catecholamines, and very low concentrations of PEA may be associated with specific psychological disorders such as ADHD. The aim of our study was to evaluate the efficacy of the Klamin extract in treating a group of subjects diagnosed with ADHD. Thirty subjects, aged 6-15, who had been diagnosed with ADHD according to the DSM-IV TR criteria, were enrolled. The supplement was administered to all the subjects, who reported to an ADHD clinic for routine follow-up visits. Observations were made and data collected over a 6-month period. After 6 months of therapy the subjects appeared to show significant improvements based on assessments of their overall functioning, behavioral aspects related to inattention and hyperactivity-impulsivity, attention functions in both the selective and sustained component and executive functions. The study appears to confirm the initial hypothesis that the Klamin extract may positively affect the expression of ADHD symptoms. Additional larger studies on the effects of Klamin on ADHD are needed to further investigate the potential of this extract in ADHD treatment.

Further replication of the synergistic interaction between LPHN3 and the NTAD gene cluster on ADHD and its clinical course throughout adulthood

Attention-Deficit/Hyperactivity Disorder (ADHD) is a common and highly heritable neuropsychiatric disorder. Despite the high heritability, the unraveling of specific genetic factors related to ADHD is hampered by its considerable genetic complexity. Recent evidence suggests that gene-gene interactions can explain part of this complexity. We examined the impact of strongly supported interaction effects between the LPHN3 gene and the NTAD gene cluster (NCAM1-TTC12-ANKK1-DRD2) in a 7-year follow-up of a clinical sample of adults with ADHD, addressing associations with susceptibility, symptomatology and stability of diagnosis. The sample comprises 548 adults with ADHD and 643 controls. Entropy-based analysis indicated a potential interaction between the LPHN3-rs6551665 and TTC12-rs2303380 SNPs influencing ADHD symptom counts. Further analyses revealed significant interaction effects on ADHD total symptoms (p=0.002), and with hyperactivity/impulsivity symptom counts (p=0.005). In the group composed by predominantly hyperactive/impulsive and combined presentation, the presence of LPHN3-rs6551665 G allele was related to increased ADHD risk only in individuals carrying the TTC12-rs2303380 AA genotype (p=0.026). Also, the same allelic constellation is involved in maintenance of ADHD in a predominantly hyperactive/impulsive or combined presentation after a 7-year follow-up (p=0.008). These observations reinforce and replicate previous evidence suggesting that an interaction effect between the LPHN3 gene and the NTAD cluster may have a role in the genetic substrate associated to ADHD also in adults. Moreover, it is possible that the interactions between LPHN3 and NTAD are specific factors contributing to the development of an ADHD phenotype with increased hyperactivity/impulsivity that is maintained throughout adulthood.

Mind-Body Therapy for Children with Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is pervasive among the pediatric population and new treatments with minimal adverse effects are necessary to be studied. The purpose of this article is to review current research studying mind–body therapies for treatment of children diagnosed with ADHD. Literature was reviewed pertaining to the effectiveness of movement-based therapies and mindfulness/meditation-based therapies for ADHD. Many positive effects of yoga, Tai Chi, physical activity, and meditation may significantly improve symptoms of ADHD among children.