Neurobiology of ADHD. Neuropharmacology. 2009;57:579-589. [PMID: 19627998 DOI: 10.1016/j.neuropharm.2009.07.026]

Comprehensive exploration of the genetic contribution of the dopaminergic and serotonergic pathways to psychiatric disorders

Psychiatric disorders are highly prevalent and display considerable clinical and genetic overlap. Dopaminergic and serotonergic neurotransmission have been shown to play an important role in many psychiatric disorders. Here we aim to assess the genetic contribution of these systems to eight psychiatric disorders (attention-deficit hyperactivity disorder (ADHD), anorexia nervosa (ANO), autism spectrum disorder (ASD), bipolar disorder (BIP), major depression (MD), obsessive-compulsive disorder (OCD), schizophrenia (SCZ) and Tourette's syndrome (TS)) using publicly available GWAS analyses performed by the Psychiatric Genomics Consortium that include more than 160,000 cases and 275,000 controls. To do so, we elaborated four different gene sets: two 'wide' selections for dopamine (DA) and for serotonin (SERT) using the Gene Ontology and KEGG pathways tools, and two'core' selections for the same systems, manually curated. At the gene level, we found 67 genes from the DA and/or SERT gene sets significantly associated with one of the studied disorders, and 12 of them were associated with two different disorders. Gene-set analysis revealed significant associations for ADHD and ASD with the wide DA gene set, for BIP with the wide SERT gene set, and for MD with the core SERT set. Interestingly, interrogation of a cross-disorder GWAS meta-analysis of the eight psychiatric conditions displayed association with the wide DA gene set. To our knowledge, this is the first systematic examination of genes encoding proteins essential to the function of these two neurotransmitter systems in these disorders. Our results support a pleiotropic contribution of the dopaminergic and serotonergic systems in several psychiatric conditions.

Childhood ADHD, Going Beyond the Brain: A Meta-Analysis on Peripheral Physiological Markers of the Heart and the Gut

Attention-Deficit/Hyperactivity Disorder (ADHD) is the most common neurodevelopmental disorder diagnosed in children. Questions regarding its increased diagnostic rates and pharmacological treatments in developing children have led to a more holistic review of the multi-system pathophysiology observed in ADHD. The dopaminergic neurotransmitter system, known for its influence on reward-motivated behaviors and motor control, and the frontostriatal systems, that mediate motor, cognition, and behavior, are associated with ADHD's development. However, studies have shown that these neural systems do not wholly account for ADHD's multilayered and heterogeneous symptom presentation. For instance, the literature suggests that emotional dysregulation, the inability to regulate one's emotional responses to provoking stimuli, is associated with increased risk for social impairment in ADHD. A broader examination of physiological systems in children with ADHD has found potential markers in the heart-brain and gut-brain axes that correspond with certain behaviors associated with emotional dysregulation in recent studies. Hence, the purpose of this meta-analysis is to aggregate ten applicable published case studies and analyze task-related heart rate reactivity (HRR; n = 5 studies) and gut microbiota (n = 5 studies) data in children with and without ADHD. Data from a total of 531 youth with ADHD and 603 youth without ADHD revealed significant small and medium effect sizes for higher Chao1 levels and Actinobacteria levels in the ADHD group, respectively, but no evidence of altered task-related HRR. Thus, further research into multi-system psychophysiological measures of emotional dysregulation and ADHD is warranted. The clinical, empirical, and educational implications of these findings are discussed.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier PROSPERO (CRD42021236819).

Attitudes and practices in the management of attention deficit hyperactivity disorder among Brazilian pediatric neurologists who responded to a national survey: a cross-sectional study

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) has a prevalence of 5.3% among children and adolescents. It is characterized by attention deficit, hyperactivity, and impulsivity.

OBJECTIVE

We aimed to conduct a survey involving pediatric neurologists in the management of ADHD and compare the results with the current literature and guidelines.

DESIGN AND SETTING

Descriptive analytical study of a virtual environment, was used Test of equality of proportions for comparison between two groups of pediatric neurologists (working as specialists for > 6 versus ≤ 6 years), with a significance level of P = 0.05.

METHODS

This cross-sectional study used a virtual questionnaire covering the steps in the diagnosis and treatment of children with ADHD. The inclusion criteria were professionals who had completed their residency/specialization in pediatric neurology and clinical neurologists working in pediatric neurology.

RESULTS

Among the 548 electronic invitations sent, 128 were considered valid. For all participants, the diagnosis was clinically based on the disease classification manuals. Combination treatment promotes improvement of symptoms (96.9%). Among psychostimulants, short-acting methylphenidate was the most commonly prescribed medication (85.2%). Headache was the most common side effect (77.3%). Altogether, 73.4% of the participants requested laboratory tests, 71.1% requested an electrocardiogram, and 42.2% requested an electroencephalogram. Pediatric neurologists working as specialists for ≤ 6 years had more frequent referrals to psycho-pedagogists for diagnosis (P = 0.03).

CONCLUSIONS

The participants complied with clinical guidelines, emphasizing the relevance of diagnostic manuals and treatment guidelines for an eminently clinical situation and enabling uniformity in quality treatment.

Modulation of Spatial Memory Deficit and Hyperactivity in Dopamine Transporter Knockout Rats via α2A-Adrenoceptors

Attention deficit hyperactivity disorder (ADHD) is manifested by a specific set of behavioral deficits such as hyperactivity, impulsivity, and inattention. The dopamine neurotransmitter system is postulated to be involved in the pathogenesis of ADHD. Guanfacine, a selective α2A-adrenoceptor agonist, is prescribed for ADHD treatment. ADHD also is known to be associated with impairment of multiple aspects of cognition, including spatial memory, however, it remains unclear how modulation of the norepinephrine system can affect these deficits. Hyperdopaminergic dopamine transporter knockout (DAT-KO) rats are a valuable model for investigating ADHD. The DAT-KO rats are hyperactive and deficient in spatial working memory. This work aimed to evaluate the effects of noradrenergic drugs on the fulfillment of spatial cognitive tasks by DAT-KO rats. The rats were tested in the Hebb - Williams maze during training and following noradrenergic drugs administration. The efficiency of spatial orientation was assessed as to how fast the animal finds an optimal way to the goal box. Testing in a new maze configuration allowed us to evaluate the effects of drug administration after the acquisition of the task rules. The behavioral variables such as the distance traveled, the time to reach the goal box, and the time spent in the error zones were analyzed. It has been observed that α2A-adrenoceptor agonist Guanfacine (0.25 mg/kg) had only a minimal inhibitory effect on hyperactivity of DAT-KO rats in the maze but significantly ameliorated their perseverative pattern of activity and reduced the time spent in the error zones. In contrast, α2A-adrenoceptor antagonist Yohimbine, at the dose of 1 mg/kg, increased the distance traveled by DAT-KO rats and elevated the number of perseverative reactions and the time spent in the error zones. Guanfacine caused minimal effects in wild-type rats, while Yohimbine altered several parameters reflecting a detrimental effect on the performance in the maze. These data indicate that modulation of α2A-adrenoceptor activity potently affects both dopamine-dependent hyperactivity and cognitive dysfunctions. Similar mechanisms may be involved in the beneficial effects of Guanfacine on cognitive deficits in ADHD patients. This study further supports the translational potential of DAT-KO rats for testing new pharmacological drugs.

Attention Deficit Hyperactivity Disorder and Bipolar Disorder: Diagnosis, Treatments, and Clinical Considerations: A Narrative Review

Attention-deficit Hyperactivity Disorder is one of the most common childhood mental health disorders, affecting about 5.6% of the population worldwide. Several studies have specifically shown a high prevalence of comorbid mood disorders, such as depression and bipolar disorder (BD), in those diagnosed with ADHD. Several common symptoms of ADHD are also found in BD, which are characterized by alternating periods of euthymia and mood disturbances. The inattention and impulsivity of ADHD can be seen in manic and hypomanic episodes of BD. Over the past decade, there has been an increased interest in research between the correlation of ADHD and pediatric bipolar disorder (PBD) in children. Some experts hypothesize that more children are comorbidly diagnosed with ADHD and PBD because of how many clinicians treat children with ADHD. Other factors, which may affect the dual diagnoses of ADHD and PBD, are overlapping diagnostic criteria for the two disorders, the inevitable biases seen when one disorder is diagnosed without the other, and related risk factors leading to prodromal relationships. By examining clinical trials, a better understanding of whether ADHD and PBD have a stepwise progression or if other factors influence these comorbidities, such as blurred lines of diagnostic criteria. Those with ADHD are also at an increased risk of impairment at work and in social settings. This manuscript explores both progression of this disease and its clinical connections to other disorders.

A Literature Review on the Efficacy and Related Neural Effects of Pharmacological and Psychosocial Treatments in Individuals With Internet Gaming Disorder

OBJECTIVE

Internet gaming disorder (IGD) has attracted considerable attention as a serious mental and public health issue worldwide. Currently, there are no established treatment guidelines for IGD. Herein, we review the latest findings on the efficacy and related neural effects of pharmacological and psychosocial treatments for individuals with IGD.

METHODS

A database search of relevant studies published between 2007 and 2020 was conducted using PubMed and Google Scholar. Twenty-seven studies were reviewed for current evidence related to the efficacy and neural effects of pharmacological and psychosocial IGD treatments.

RESULTS

Pharmacological studies suggest that bupropion may play a significant role in IGD. Additionally, nuclear imaging studies on IGD have demonstrated functional impairment of the dopamine system, providing a neurobiological basis for the efficacy of dopamineenhancing drugs. Among the various psychosocial interventions, current evidence suggests that cognitive behavioral therapy may be an effective intervention for IGD. Cognitive behavioral therapy and bupropion were found to influence resting-state functional connectivity within the cortico-subcortical circuit and default mode network, suggesting a possible neural mechanism. Innovative approaches, including virtual reality treatment, residential camps, voluntary abstinence, and transcranial direct current stimulation, have shown promising results. However, methodological limitations, such as the absence of proper controls, small sample sizes, short duration, inconsistency of inclusion criteria across studies, and self-report measures of outcome, hamper conclusions regarding the efficacy of treatments.

CONCLUSION

Ongoing basic research and clinical trials overcoming these limitations could add to the existing knowledge on IGD and contribute to the development of evidence-based treatments.

ADHD symptoms in neurometabolic diseases: Underlying mechanisms and clinical implications

Neurometabolic diseases (NMDs) are typically caused by genetic abnormalities affecting enzyme functions, which in turn interfere with normal development and activity of the nervous system. Although the individual disorders are rare, NMDs are collectively relatively common and often lead to lifelong difficulties and high societal costs. Neuropsychiatric manifestations, including ADHD symptoms, are prominent in many NMDs, also when the primary biochemical defect originates in cells and tissues outside the nervous system. ADHD symptoms have been described in phenylketonuria, tyrosinemias, alkaptonuria, succinic semialdehyde dehydrogenase deficiency, X-linked ichthyosis, maple syrup urine disease, and several mitochondrial disorders, but are probably present in many other NMDs and may pose diagnostic and therapeutic challenges. Here we review current literature linking NMDs with ADHD symptoms. We cite emerging evidence that many NMDs converge on common neurochemical mechanisms that interfere with monoamine neurotransmitter synthesis, transport, metabolism, or receptor functions, mechanisms that are also considered central in ADHD pathophysiology and treatment. Finally, we discuss the therapeutic implications of these findings and propose a path forward to increase our understanding of these relationships.

The effects of the dopamine D2/3 agonist quinpirole on incentive value and palatability-based choice in a rodent model of attention-deficit/hyperactivity disorder

RATIONALE

Palatability and incentive value influence animal food choice. Dopamine D2/3 receptor signaling may mediate the effects of palatability and incentive value on choice. Dopamine signaling is disrupted in attention-deficit hyperactivity disorder (ADHD). Investigating behavioral choice processes under D2/3 receptor agonists will help elucidate behavioral and pharmacological correlates of ADHD.

OBJECTIVES

To determine (1) how changes in incentive value affects choice of actions for outcomes that differ in palatability; (2) the effects of the D2/3 agonist quinpirole on choice based on palatability and incentive value; (3) how choice differs in spontaneously hypertensive rats (SHR; ADHD model) compared with control strains.

METHODS

Rats responded instrumentally for two food outcomes (chocolate and grain pellets) that differed in palatability. Following specific satiety of one outcome, rats underwent a choice test. Prior to the choice test, rats were given intra-peritoneal quinpirole (0.01-0.1 mg/kg) body weight. These manipulations were conducted in three strains of rats: SHR rats; the normotensive Wistar-Kyoto (WKY) controls; and Wistar outbred (WIS) controls.

RESULTS

All rat strains responded more vigorously for chocolate pellets compared with grain pellets. Quinpirole reduced the effects of palatability and dose-dependently increased the effects of incentive value on choice. SHR rats were the least influenced by incentive value, whereas WKY rats were the least influenced by palatability.

CONCLUSIONS

These results show that D2/3 signaling modulates choice based on palatability and incentive value. Disruption of this process in SHR rats may mirror motivational impairments observed in ADHD.

Canine hyperactivity, impulsivity, and inattention share similar demographic risk factors and behavioural comorbidities with human ADHD

Attention-deficit hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder impairing the quality of life of the affected individuals. The domestic dog can spontaneously manifest high hyperactivity/impulsivity and inattention which are components of human ADHD. Therefore, a better understanding of demographic, environmental and behavioural factors influencing canine hyperactivity/impulsivity and inattention could benefit both humans and dogs. We collected comprehensive behavioural survey data from over 11,000 Finnish pet dogs and quantified their level of hyperactivity/impulsivity and inattention. We performed generalised linear model analyses to identify factors associated with these behavioural traits. Our results indicated that high levels of hyperactivity/impulsivity and inattention were more common in dogs that are young, male and spend more time alone at home. Additionally, we showed several breed differences suggesting a substantial genetic basis for these traits. Furthermore, hyperactivity/impulsivity and inattention had strong comorbidities with compulsive behaviour, aggressiveness and fearfulness. Multiple of these associations have also been identified in humans, strengthening the role of the dog as an animal model for ADHD.

Functional MHCI deficiency induces ADHD-like symptoms with increased dopamine D1 receptor expression

Inappropriate synaptic development has been proposed as a potential mechanism of neurodevelopmental disorders, including attention-deficit hyperactivity disorder (ADHD). Major histocompatibility complex class I (MHCI), an immunity-associated molecule expressed by neurons in the brain, regulates synaptic development; however, the involvement of MHCI in these disorders remains elusive. We evaluated whether functional MHCI deficiency induced by β2m^-/-Tap1^-/- double-knockout in mice leads to abnormalities akin to those seen in neurodevelopmental disorders. We found that functional MHCI deficiency induced locomotor hyperactivity, motor impulsivity, and attention deficits, three major symptoms of ADHD. In contrast, these mice showed normal spatial learning, behavioral flexibility, social behavior, and sensorimotor integration. In the analysis of the dopamine system, upregulation of dopamine D1 receptor (D1R) expression in the nucleus accumbens and a greater locomotor response to D1R agonist SKF 81297 were found in the functional MHCI-deficient mice. Low-dose methylphenidate, used for the treatment of ADHD patients, alleviated the three behavioral symptoms and suppressed c-Fos expression in the D1R-expressing medium spiny neurons of the mice. These findings reveal an unexpected role of MHCI in three major symptoms of ADHD and may provide a novel landmark in the pathogenesis of ADHD.

A novel role for the ADHD risk gene latrophilin-3 in learning and memory in Lphn3 knockout rats

Latrophilins (LPHNs) are adhesion G protein-coupled receptors with three isoforms but only LPHN3 is brain specific (caudate, prefrontal cortex, dentate, amygdala, and cerebellum). Variants of LPHN3 are associated with ADHD. Null mutations of Lphn3 in rat, mouse, zebrafish, and Drosophila result in hyperactivity, but its role in learning and memory (L&M) is largely unknown. Using our Lphn3 knockout (KO) rats we examined the cognitive abilities, long-term potentiation (LTP) in CA1, NMDA receptor expression, and neurohistology from heterozygous breeding pairs. KO rats were impaired in egocentric L&M in the Cincinnati water maze, spatial L&M and cognitive flexibility in the Morris water maze (MWM), with no effects on conditioned freezing, novel object recognition, or temporal order recognition. KO-associated locomotor hyperactivity had no effect on swim speed. KO rats had reduced early-LTP but not late-LTP and had reduced hippocampal NMDA-NR1 expression. In a second experiment, KO rats responded to a light prepulse prior to an acoustic startle pulse, reflecting visual signal detection. In a third experiment, KO rats given extra MWM pretraining and hidden platform overtraining showed no evidence of reaching WT rats' levels of learning. Nissl histology revealed no structural abnormalities in KO rats. LPHN3 has a selective effect on egocentric and allocentric L&M without effects on conditioned freezing or recognition memory.

Perinatal Acetaminophen Exposure and Childhood Attention-Deficit/Hyperactivity Disorder (ADHD): Exploring the Role of Umbilical Cord Plasma Metabolites in Oxidative Stress Pathways

Oxidative stress mechanisms may explain associations between perinatal acetaminophen exposure and childhood attention-deficit hyperactivity disorder (ADHD). We investigated whether the changes in umbilical cord plasma amino acids needed to synthesize the antioxidant glutathione and in the oxidative stress biomarker 8-hydroxy-deoxyguanosine may explain the association between cord plasma acetaminophen and ADHD in the Boston Birth Cohort (BBC). Mother–child dyads were followed at the Boston Medical Center between 1998 and 2018. Cord plasma analytes were measured from archived samples collected at birth. Physician diagnoses of childhood ADHD were obtained from medical records. The final sample consisted of 568 participants (child mean age [SD]: 9.3 [3.5] years, 315 (52.8%) male, 248 (43.7%) ADHD, 320 (56.3%) neurotypical development). Cord unmetabolized acetaminophen was positively correlated with methionine (R = 0.33, p < 0.001), serine (R = 0.30, p < 0.001), glycine (R = 0.34, p < 0.001), and glutamate (R = 0.16, p < 0.001). Children with cord acetaminophen levels >50th percentile appeared to have higher risk of ADHD for each increase in cord 8-hydroxy-deoxyguanosine level. Adjusting for covariates, increasing cord methionine, glycine, serine, and 8-hydroxy-deoxyguanosine were associated with significantly higher odds for childhood ADHD. Cord methionine statistically mediated 22.1% (natural indirect effect logOR = 0.167, SE = 0.071, p = 0.019) and glycine mediated 22.0% (natural indirect effect logOR = 0.166, SE = 0.078, p = 0.032) of the association between cord acetaminophen >50th percentile with ADHD. Our findings provide some clues, but additional investigation into oxidative stress pathways and the association of acetaminophen exposure and childhood ADHD is warranted.

Histological, transmission electron microscopic, and immunohistochemical study of the adrenal gland in the Persian squirrel (Sciurus anomalus)

This research was aimed to present the histological and ultrastructure properties of the adrenal gland in the Persian squirrel. Two male and female animals were included in the study. The adrenal gland was bean-shaped and located on the cranial pole of kidney. The enveloping capsule was dense connective tissue that reacted positively with Periodic-Acid Schiff (PAS) and Masson trichrome stainings. The parenchyma of the gland consisted of two-part, namely cortex and medulla; the cortex had three layers: zona glomerulosa (ZG), zona fasciculata (ZF), and zona reticularis (ZR). The cells of the ZG were mainly spherical and ovoid with circular arrangement and few lipid droplets in TEM micrographs. The cells of the ZF were columnar and spherical that were arranged in cord-like rows. Transmission electron microscopy (TEM) indicated conspicuous lipid droplets and mitochondria in this zone. The cells of the ZR were arranged in a tangled networks and were almost similar to those in the ZF. TEM images showed fewer lipid vesicles in the ZR compared to the ZF and ZG. Chromaffin cells were located in the medulla of the adrenal gland in two layers. TEM images showed that some of them were smaller and contained fewer secretory granules; other cells were larger and contained more electron-dense secretory granules. Immunofluorescence staining showed that steroidogenic factor 1 (SF1) expressed from cortex to the corticomedullary junction (CMJ) and tyrosine hydroxylase (TH) expressed in the medulla. In conclusion, the results indicated both similarities and differences between the adrenal gland of the Persian squirrel and other animals such as mammals and rodents.

Effects of an Adenosine A2A Receptor Antagonist on Striatal Dopamine D2-Type Receptor Availability: A Randomized Control Study Using Positron Emission Tomography

Introduction: Altered dopaminergic neurotransmission, especially in the functioning of dopamine D2-type receptors, is considered central to the etiology of a variety of neuropsychiatric disorders. In particular, individuals with substance use disorders have been consistently observed to exhibit lower D2-type receptor availability (quantified as binding potential; BPND) using positron emission tomography (PET). Upregulation of D2-type receptor density thus may therefore provide a therapeutic effect for substance use disorders. Importantly, in vitro studies reveal that D2 receptors coexist with adenosine 2A (A2A) receptors to form the highest density of heteromers in the whole striatum, and there is a functional interaction between these two receptors. As such, blockade of A2A receptor's function may prevent D2 receptor downregulation, yet no study has currently examined this hypothesis in humans. Methods and Analysis: This double-blind, randomized controlled trial aims to evaluate the effect of the A2A receptor antagonist istradefylline (compared to placebo) on both dopamine D2-type receptor availability in the human brain and on neuropsychological measurements of impulsivity. It is hypothesized that istradefylline will both increase striatal D2-type BPND and improve control of impulsivity more than placebo. Forty healthy participants, aged 20-65 with no history of psychiatric or neurological disorders, will be recruited and randomized into two groups and will undergo [11C]raclopride PET, once before and once after administration of either 40 mg/day istradefylline or placebo for 2 weeks. Neuropsychological measurements will be administered on the same days of the PET scans. Ethics and Dissemination: The study protocol was approved by the Certified Review Boards (CRB) of National Center of Neurology and Psychiatry (CR18-011) and prospectively registered with the Japan Registry of Clinical Trials (jRCTs031180131; https://jrct.niph.go.jp/latest-detail/jRCTs031180131). The findings of this study will be disseminated through peer reviewed scientific journals and conferences. Clinical Trial Registration:www.ClinicalTrials.gov, identifier jRCTs031180131.

Gut microbiota and probiotic therapy in ADHD: A review of current knowledge

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder characterized by inattention, impulsivity and hyperactivity. The etiology of the disorder is multi-factorial, with a main focus on genetic factors. However, emerging research shows the involvement of changes and imbalances in the intestinal microbiota. Evidence for the influence of gut microbiota on brain development and neurogenesis is clear. We present a review of emerging research on the microbiota in the ADHD population. The aim of this study was to summarize the current state of knowledge on ADHD, to identify gaps in knowledge, as well as to indicate the directions of new research. Thanks to the researchers that would be possible to better understand the complexity of ADHD etiology, especially the role of the intestinal microbiota in the pathogenesis of the disorder. Pubmed, Scopus and Google Scholar databases were used while writing the review. Numerous studies show that probiotic supplementation can have a positive effect on the course of neurodevelopmental disorders, including ADHD. Unfortunately, clinical studies that were identified are mostly inconclusive, and more high-quality research is needed to produce robust evidence for therapy based on interventions targeting microbiota.

The Role of Preclinical Models in Creatine Transporter Deficiency: Neurobiological Mechanisms, Biomarkers and Therapeutic Development

Creatine (Cr) Transporter Deficiency (CTD) is an X-linked metabolic disorder, mostly caused by missense mutations in the SLC6A8 gene and presenting with intellectual disability, autistic behavior, and epilepsy. There is no effective treatment for CTD and patients need lifelong assistance. Thus, the research of novel intervention strategies is a major scientific challenge. Animal models are an excellent tool to dissect the disease pathogenetic mechanisms and drive the preclinical development of therapeutics. This review illustrates the current knowledge about Cr metabolism and CTD clinical aspects, with a focus on mainstay diagnostic and therapeutic options. Then, we discuss the rodent models of CTD characterized in the last decade, comparing the phenotypes expressed within clinically relevant domains and the timeline of symptom development. This analysis highlights that animals with the ubiquitous deletion/mutation of SLC6A8 genes well recapitulate the early onset and the complex pathological phenotype of the human condition. Thus, they should represent the preferred model for preclinical efficacy studies. On the other hand, brain- and cell-specific conditional mutants are ideal for understanding the basis of CTD at a cellular and molecular level. Finally, we explain how CTD models might provide novel insight about the pathogenesis of other disorders, including cancer.

Transdiagnostic neuroimaging of reward system phenotypes in ADHD and comorbid disorders

ADHD is a disorder characterized by changes in the reward system and which is highly comorbid with other mental disorders, suggesting common neurobiological pathways. Transdiagnostic neuroimaging findings could help to understand whether a dysregulated reward pathway might be the actual link between ADHD and its comorbidities. We here synthesize ADHD neuroimaging findings on the reward system with findings in obesity, depression, and substance use disorder including their comorbid appearance regarding neuroanatomical features (structural MRI) and activation patterns (resting-state and functional MRI). We focus on findings from monetary-incentive-delay (MID) and delay-discounting (DD) tasks and then review data on striatal connectivity and volumetry. Next, for better understanding of comorbidity in adult ADHD, we discuss these neuroimaging features in ADHD, obesity, depression and substance use disorder and ask whether ADHD heterogeneity and comorbidity are reflected by a common dysregulation in the reward system. Finally, we highlight conceptual issues related to heterogeneous paradigms, different phenotyping, longitudinal prediction and highlight some promising future directions for using striatal reward functioning as a clinical biomarker.

Genetic variations influence brain changes in patients with attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) is a neurological and neurodevelopmental childhood-onset disorder characterized by a persistent pattern of inattentiveness, impulsiveness, restlessness, and hyperactivity. These symptoms may continue in 55-66% of cases from childhood into adulthood. Even though the precise etiology of ADHD is not fully understood, it is considered as a multifactorial and heterogeneous disorder with several contributing factors such as heritability, auxiliary to neurodevelopmental issues, severe brain injuries, neuroinflammation, consanguineous marriages, premature birth, and exposure to environmental toxins. Neuroimaging and neurodevelopmental assessments may help to explore the possible role of genetic variations on ADHD neuropsychobiology. Multiple genetic studies have observed a strong genetic association with various aspects of neuropsychobiological functions, including neural abnormalities and delayed neurodevelopment in ADHD. The advancement in neuroimaging and molecular genomics offers the opportunity to analyze the impact of genetic variations alongside its dysregulated pathways on structural and functional derived brain imaging phenotypes in various neurological and psychiatric disorders, including ADHD. Recently, neuroimaging genomic studies observed a significant association of brain imaging phenotypes with genetic susceptibility in ADHD. Integrating the neuroimaging-derived phenotypes with genomics deciphers various neurobiological pathways that can be leveraged for the development of novel clinical biomarkers, new treatment modalities as well as therapeutic interventions for ADHD patients. In this review, we discuss the neurobiology of ADHD with particular emphasis on structural and functional changes in the ADHD brain and their interactions with complex genomic variations utilizing imaging genetics methodologies. We also highlight the genetic variants supposedly allied with the development of ADHD and how these, in turn, may affect the brain circuit function and related behaviors. In addition to reviewing imaging genetic studies, we also examine the need for complementary approaches at various levels of biological complexity and emphasize the importance of combining and integrating results to explore biological pathways involved in ADHD disorder. These approaches include animal models, computational biology, bioinformatics analyses, and multimodal imaging genetics studies.

Prenatal origins of neuropsychiatric diseases

AIM

The main objective is to review the available evidence in the literature for developmental origins of neuropsychiatric diseases and their underlying mechanisms. We also probe emerging cutting-edge prenatal MR imaging tools and their future role in advancing our understanding the prenatal footprints of neuropsychiatric disorders.

OBSERVATIONS

Both human and animal studies support early intrauterine origins of neuropsychiatric disease, particularly autism spectrum disorders (ASD), attention and hyperactivity disorders, schizophrenia, depression, anxiety and mood disorders. Specific mechanisms of intrauterine injury include infection, inflammation, hypoxia, hypoperfusion, ischaemia polysubstance use/abuse, maternal mental health and placental dysfunction.

CONCLUSIONS AND RELEVANCE

There is ample evidence to suggest developmental vulnerability of the foetal brain to intrauterine exposures that increases and individual's risk for neuropsychiatric disease, especially the risk of ASD, depression and anxiety. Elucidating the exact timing and mechanisms of injury can be difficult and require novel, non-invasive approaches to the study emerging structural and functional brain development of the foetus. Clinical care should both emphasise maternal health during pregnancy, as well as close, continued monitoring for at risk offspring throughout young adulthood for the early identification and treatment of neuropsychiatric diseases.

Advertising Influences Food Choices of University Students With ADHD

Objective: Previous research in adults with ADHD showed high rates of obesity and unhealthy food choices. There is evidence that contextual cues, for example, advertisements, influence food choices. This study assessed the sensitivity of university students with ADHD to advertised food. Method: University students (N = 457) with and without ADHD participated in a cafeteria field experiment. Food choices were examined in periods of advertising either healthy or unhealthy sandwiches. Results: Students with ADHD (a) chose less healthy food items, (b) were more influenced by advertising, (c) showed the same overall healthy food choices as controls when exposed to healthy advertising. Conclusion: Students with ADHD chose unhealthier foods at the cafeteria but were also more influenced by advertising. Healthy food advertisements raised their healthy food choices. As this population has strong association with unhealthy dietary patterns, it is important to investigate the influence of food cues on their eating habits.

Abnormal hemispheric asymmetry of both brain function and structure in attention deficit/hyperactivity disorder: a meta-analysis of individual participant data

Aberration in the asymmetric nature of the human brain is associated with several mental disorders, including attention deficit/hyperactivity disorder (ADHD). In ADHD, these aberrations are thought to reflect key hemispheric differences in the functioning of attention, although the structural and functional bases of these defects are yet to be fully characterized. In this study, we applied a comprehensive meta-analysis to multimodal imaging datasets from 627 subjects (303 typically developing control [TDCs] and 324 patients with ADHD) with both resting-state functional and structural magnetic resonance imaging (MRI), from seven independent publicly available datasets of the ADHD-200 sample. We performed lateralization analysis and calculated the combined effects of ADHD on each of three cortical regional measures (grey matter volume - GMV, fractional amplitude of low frequency fluctuations at rest -fALFF, and regional homogeneity -ReHo). We found that compared with TDC, 68%,73% and 66% of regions showed statistically significant ADHD disorder effects on the asymmetry of GMV, fALFF, and ReHo, respectively, (false discovery rate corrected, q = 0.05). Forty-one percent (41%) of regions had both structural and functional abnormalities in asymmetry, located in the prefrontal, frontal, and subcortical cortices, and the cerebellum. Furthermore, brain asymmetry indices in these regions were higher in children with more severe ADHD symptoms, indicating a crucial pathoplastic role for asymmetry. Our findings highlight the functional asymmetry in ADHD which has (1) a strong structural basis, and thus is likely to be developmental in nature; and (2) is strongly linked to symptom burden and IQ and may carry a possible prognostic value for grading the severity of ADHD.

Perinatal exposure to paracetamol: Dose and sex-dependent effects in behaviour and brain's oxidative stress markers in progeny

Paracetamol (PAR) has been employed worldwide for pain and fever treatment during pregnancy and lactation. Epidemiologic studies have shown that exposure to PAR can increase the risk for developmental disorders, such as attention-deficit hyperactive disorder and autism spectrum disorder. This study aimed to investigate if gestational and lactational exposure to human-relevant doses of PAR could alter behavioural and brain oxidative stress parameters in the rat`s offspring. Wistar dams were gavaged daily with water or PAR (35 mg/kg/ or 350 mg/kg) during gestational day 6 to weaning (postnatal day 21). Behavioural assessments occurred at post-natal days 10 (nest seeking test), 27 (behavioural stereotypy) and 28 (three chamber sociability test and open field). Concentration of advanced oxidation protein products (AOPP), reduced glutathione (GSH), lipid hydroperoxides (LOOH) and activity of superoxide dismutase (SOD) were estimate in prefrontal cortex, hippocampus, striatum and cerebellum of 22-day-old rats. Compared to CON animals, males exposed to PAR during pregnancy and lactation augmented apomorphine-induced stereotyped behaviour (350 mg/kg) and ambulation in open-field test (35 mg/kg). Reduced exploratory behaviour in three chamber sociability test was observed in pups exposed to PAR at 350 mg/kg in both sexes. PAR treatment decreased hippocampal GSH level and striatal SOD activity in males exposed to 35 mg/kg, suggesting the vulnerability of these areas in PAR-induced developmental neurotoxicity. Findings suggest PAR use during pregnancy and lactation as a potential risk factor for neurodevelopmental disorders with males being more susceptible.

Differential Treatment Effects of Methylphenidate and Atomoxetine on Executive Functions in Children with Attention-Deficit/Hyperactivity Disorder

Objectives: This study aimed to compare the efficacy of methylphenidate and atomoxetine on improving executive functions among children with attention-deficit/hyperactivity disorder (ADHD). Methods: This was an open-label, head-to-head, 3-month, randomized clinical trial with two-arm parallel-treatment groups: osmotic-release oral system methylphenidate (OROS-MPH; n = 79) and atomoxetine once daily (n = 78). Three major domains of executive functions were assessed, including response selection/inhibition, flexibility, and planning/working memory. The neuropsychological measures included the Conners' continuous performance test and the Cambridge Neuropsychological Test Automated Battery. Results: We found that both treatment groups showed improvement in executive functions (p-value <0.05 for the major indices of each domain). In addition, OROS-MPH was associated with a greater magnitude of improvement in the response selection/inhibition; the slope for detectability improvement in the Conners' continuous performance test was 0.06 for atomoxetine and 0.15 for OROS-MPH (p-value <0.01); the slope in rapid visual information processing was 2.22 for atomoxetine and 3.45 for OROS-MPH (p-value <0.05). Conclusion: Both OROS-MPH and atomoxetine improved various domains of executive functions in children with ADHD. There is greater improvement in response selection/inhibition among patients treated with OROS-MPH than those with atomoxetine. This trial was registered with ClinicalTrials.gov (no. NCT00916786).

Caudate and cerebellar involvement in altered P2 and P3 components of GO/NoGO evoked potentials in children with attention-deficit/hyperactivity disorder

Previous studies showed reduced activity of the anterior cingulate cortex (ACC) and supplementary motor area during inhibition in children with attention-deficit/hyperactivity disorder (ADHD). This study aimed to investigate deep brain generators underlying alterations of evoked potential components triggered by visual GO/NoGO tasks in children with ADHD compared with typically developing children (TDC). Standardized weighted low-resolution electromagnetic tomography (swLORETA) source analysis showed that lower GO-P3 component in children with ADHD was explained not only by a reduced contribution of the frontal areas but also by a stronger contribution of the anterior part of the caudate nucleus in these children compared with TDC. While the reduction of the NoGO-P3 component in children with ADHD was essentially explained by a reduced contribution of the dorsal ACC, the higher NoGO-P2 amplitude in these children was concomitant to the reduced contribution of the dorsolateral prefrontal cortex, the insula, and the cerebellum. These data corroborate previous findings showed by fMRI studies and offered insight relative to the precise time-related contribution of the caudate nucleus and the cerebellum during the automatic feature of inhibition processes in children with ADHD. These results were discussed regarding the involvement of the fronto-basal ganglia and fronto-cerebellum networks in inhibition and attention alterations in ADHD.

Primary dysmenorrhea in adolescents: Association with attention deficit hyperactivity disorder and psychological symptoms

OBJECTIVE

No prior study has investigated the relation of primary dysmenorrhea (PD) with attention deficit hyperactivity disorder (ADHD) symptoms in adolescent age groups. This study aimed to investigate the relationship of PD with ADHD and psychological symptoms among adolescents. Another objective was to examine the PD related non-psychogenic factors and sleep quality.

MATERIALS AND METHODS

Two hundred nine adolescent girls who applied to policlinics for various reasons were enrolled. All participants completed self-report questionnaires. Questionnaire for sociodemographic data, menstrual pattern and dysmenorrhea in adolescents, Visual analog scale, Pittsburgh Sleep Quality Index, DSM-5 Level 2 Sleep Disorders Scale, Brief Symptom Inventory, and the Turgay Diagnostic and Statistical Manual of Mental Disorders, 4th edition-Based Child and Adolescent Disruptive Behavior Disorders Screening and Rating Scale were used to measure outcomes.

RESULTS

A hundred and four (49.8%) adolescents reported having pain that affects daily activities during menstruation. These adolescents had worse sleep quality, more inattention and hyperactivity-impulsivity problems, and other psychological symptoms of anxiety, depression, somatization, negative self-perception, and hostility in comparison to others (P < 0.05). The menstrual pain severity, measured by VAS, was positively correlated with ADHD symptoms and all other psychological parameters (P < 0.05).

CONCLUSION

PD affecting daily-activities may be related to ADHD symptoms and psychiatric distress. Future studies are needed to support the association between ADHD and PD. Assessing the psychiatric problems of adolescents with dysmenorrhea is important.

Emotional scene processing in children and adolescents with attention deficit/hyperactivity disorder: a systematic review

"Impairments in emotional information processing are frequently reported in attention deficit hyperactivity disorder (ADHD) at a voluntary, explicit level (e.g., emotion recognition) and at an involuntary, implicit level (e.g., emotional interference). Most of previous studies have used faces with emotional expressions, rarely examining other important sources of information usually co-occurring with faces in our every day experience. Here, we examined how the emotional content of an entire visual scene depicting real-world environments and situations is processed in ADHD. We systematically reviewed in PubMed, SCOPUS and ScienceDirect, using the PRISMA guidelines, empirical studies published in English until March 2019, about processing of visual scenes, with or without emotional content, in children and adolescents with ADHD. We included 17 studies among the 154 initially identified. Fifteen used scenes with emotional content (which was task-relevant in seven and irrelevant in eight studies) and two used scenes without emotional content. Even though the interpretation of the results differed according to the theoretical model of emotions of the study and the presence of comorbidity, differences in scene information processing between ADHD and typically developing children and adolescents were reported in all but one study. ADHD children and adolescents show difficulties in the processing of emotional information conveyed by visual scenes, which may stem from a stronger bottom-up impact of emotional stimuli in ADHD, increasing the emotional experience, and from core deficits of the disorder, decreasing the overall processing of the scene".

Attention-deficit/hyperactivity disorder and the explore/exploit trade-off

The ability to maximize rewards and minimize the costs of obtaining them is vital to making advantageous explore/exploit decisions. Exploratory decisions are theorized to be greater among individuals with attention-deficit/hyperactivity disorder (ADHD), potentially due to deficient catecholamine transmission. Here, we examined the effects of ADHD status and methylphenidate, a common ADHD medication, on explore/exploit decisions using a 6-armed bandit task. We hypothesized that ADHD participants would make more exploratory decisions than controls, and that MPH would reduce group differences. On separate study days, adults with (n = 26) and without (n = 23) ADHD completed the bandit task at baseline, and after methylphenidate or placebo in counter-balanced order. Explore/exploit decisions were modeled using reinforcement learning algorithms. ADHD participants made more exploratory decisions (i.e., chose options without the highest expected reward value) and earned fewer points than controls in all three study days, and methylphenidate did not affect these outcomes. Baseline exploratory choices were positively associated with hyperactive ADHD symptoms across all participants. These results support several theoretical models of increased exploratory choices in ADHD and suggest the unexplained variance in ADHD decisions may be due to less value tracking. The inability to suppress actions with little to no reward value may be a key feature of hyperactive ADHD symptoms.

Temperamental risk factors in young adults with ADHD symptoms

Introduction: In recent years, numerous studies have focused on the analysis of the primary mechanisms and forms of therapy in children and adolescents with attention deficit hyperactivity disorder (ADHD). The analysis of such topics among similarly diagnosed young adults is only beginning to gain popularity. The present article attempts to answer the question of whether the level of individual temperament traits will predict an increase in the severity of ADHD symptoms in young adults.

Materials and methods: The questionnaire study involved 111 young adults aged from 18 to 28 (M= 23; SD= 2.12; 70 women and 41 men). Fifty-one people were included in the clinical group, and sixty were qualified for the control one. The participants of the study completed a health questionnaire and a structured diagnostic interview on ADHD symptoms in adults (DIVA 2.0) and a questionnaire for the diagnosis of basic, biologically determined dimensions of human personality (FCZ-KT (R)).

Results: The results indicate a significant role of four temperament traits that may be considered as specific risk factors for the aggravation of ADHD symptoms. These include briskness, rhythm, endurance and activity.

Conclusions: In Strelau’s Regulatory Theory of Temperament, the variability of temperament traits (in the Polish population) is attributed in 44% to genetic factors. The remaining 56% indicate non-genetic factors. The obtained results may indicate which factors are important in therapeutic work both in the group of young adults with ADHD symptoms, and may also constitute a source of information for parents or teachers regarding younger children with these symptoms.

Disorder-specific alterations of tactile sensitivity in neurodevelopmental disorders

Alterations of tactile processing have long been identified in autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD). However, the extent to which these alterations are disorder-specific, rather than disorder-general, and how they relate to the core symptoms of each disorder, remains unclear. We measured and compared tactile detection, discrimination, and order judgment thresholds between a large sample of children with ASD, ADHD, ASD + ADHD combined and typically developing controls. The pattern of results suggested that while difficulties with tactile detection and order judgement were more common in children with ADHD, difficulties with tactile discrimination were more common in children with ASD. Interestingly, in our subsequent correlation analyses between tactile perception and disorder-specific clinical symptoms, tactile detection and order judgment correlated exclusively with the core symptoms of ADHD, while tactile discrimination correlated exclusively with the symptoms of ASD. When taken together, these results suggest that disorder-specific alterations of lower-level sensory processes exist and are specifically related to higher-level clinical symptoms of each disorder.

Attention deficit/hyperactivity disorder and epilepsy

PURPOSE OF REVIEW

Attention deficit/hyperactivity disorder (ADHD) is a frequent comorbidity in patients with epilepsy and is associated with important psychosocial and academic consequences. Evidence are now available to guide diagnosis and treatment of patients with both ADHD and epilepsy.

RECENT FINDINGS

The prevalence of ADHD varies from 12 to 39% in patients with newly diagnosed epilepsy to 70% in drug-resistant epilepsy. The diagnosis of ADHD requires parent-validated and teacher-validated rating scales, based on the Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV and DSM-V, to confirm the information in the rating scales by interviewing parents and to exclude other causes of symptoms. Treatment with methylphenidate is associated with clinically significant improvement of ADHD symptoms in 60-75% of patients. Recent data reinforce the hypothesis that ADHD medications do not increase risk of seizures, even in patients with epilepsy. Beyond pharmacological management, experts have recommended to include multidisciplinary involvement in transition clinics for patients with both comorbid ADHD and epilepsy.

SUMMARY

Management of ADHD in patients with epilepsy requires implementation of evidence-based data in clinical practice both for diagnosis and treatment. Currently, there is no specific treatment of ADHD associated with epilepsy and its treatment is based on the usual treatments of ADHD, with reassuring data about their safety in epilepsy.

Task-related motivation and academic achievement in children and adolescents with ADHD

Academic impairment in individuals with attention-deficit/hyperactivity disorder (ADHD) is in part due to reduced motivation for academic tasks, which is likely to vary as a function of task characteristics. The current study employed a new questionnaire-the Child and Adolescent Motivational Profile (CHAMP)-to examine; (1) which task characteristic participants with ADHD perceive as most motivating relative to typically developing peers (TDP) and (2) whether these differences mediate academic functioning. 34 participants with ADHD and 435 TDP (8-16 years) completed the CHAMP. Academic achievement (grade point average) and self-reported positive/negative classroom experiences were recorded. No task characteristics were rated higher in terms of their motivational salience in the ADHD group than in the control sample. Marked/graded, Socially evaluated, Collaborative, Requiring focus and Cognitively challenging task characteristics were rated significantly lower by the ADHD group than controls. The lower rating of Socially evaluated was explained by comorbid ODD symptoms. Cognitively challenging was rated as particularly unmotivating by individuals with ADHD. ADHD was associated with a decreased GPA and a more negative classroom experience. The associations between ADHD and GPA/negative classroom experience were both partially mediated by scores on the Cognitively Challenging scale. For children and adolescents with ADHD tasks that are cognitively challenging were not particularly motivating. To increase task motivation, and improve academic performance of individuals with ADHD, it may be important to include rewarded task elements as they are appraised as particularly motivating by these individuals and this appraisal was similar to that of TDP.

Viloxazine in the Treatment of Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder in children. Over the past twenty years, research on the disease and its characteristics and treatment options has grown exponentially. The first-line pharmacologic treatment of ADHD is stimulants, which have a response rate of ~70%. With the support of four phase 3 studies involving more than 1,000 pediatric patients 6-17 years old, the FDA has approved the non-stimulant, serotonin-norepinephrine modulating agent (SNMA) viloxazine in an extended-release capsule (viloxazine ER) for treatment of ADHD in children aged 6-17. Viloxazine modulates serotonergic activity as a selective 5-HT2_2B receptor antagonist and 5-HT_2C receptor agonist and moderately inhibits norepinephrine transporter (NET), thus blocking the reuptake of norepinephrine. A phase 2 study by Johnson et al. found that once-daily dosing of viloxazine ER in 200, 300, or 400 mg dosages in children with ADHD for eight weeks resulted in a statistically significant reduction of ADHD-RS-IV total score. A post hoc analysis of data from four phase 3, randomized, placebo-controlled, double-blind, three-arm, clinical trials by Faraone et al. found that early response to viloxazine treatment, defined as a change in ADHD-RS-5 total score at week 2, best predicted the treatment response at week 6 [75% positive predictive power (PPP), 75% sensitivity]. Proper treatment of the symptoms and comorbidities associated with ADHD is crucial in improving a patient's quality of life, cognitive function, and overall therapeutic outcomes. Viloxazine's mechanism of action, clinical effects, and limited side effect profile point toward the drug's relevance in the treatment of ADHD.

Attention-deficit/hyperactivity disorder and brain metabolites from proton magnetic resonance spectroscopy: a systematic review and meta-analysis protocol

Despite major advances in the study of the brain, investigations on neurochemistry in vivo still lack the solid ground of more established methods, such as structural and functional magnetic resonance imaging. Proton magnetic resonance spectroscopy (MRS) is a technique that might potentially fill in this gap. Nevertheless, studies using this approach feature great methodological heterogeneity, such as varying voxel of choice, differences on emphasized metabolites, and absence of a standardized unit. In this study, we present a methodology for creating a systematic review and meta-analysis for this kind of scientific evidence using the prototypical case of attention-deficit/hyperactivity disorder. Systematic review registration: International Prospective Register of Systematic Reviews (PROSPERO), CRD42018112418.

How to Improve Behavioral Parent and Teacher Training for Children with ADHD: Integrating Empirical Research on Learning and Motivation into Treatment

Attention deficit hyperactivity disorder [ADHD] is one of the most common psychiatric disorders of childhood with poor prognosis if not treated effectively. Recommended psychosocial evidence-based treatment for preschool and school-aged children is behavioral parent and teacher training [BPT]. The core elements of BPT are instrumental learning principles, i.e., reinforcement of adaptive and the ignoring or punishment of non-adaptive behaviors together with stimulus control techniques. BPT is moderately effective in reducing oppositional behavior and improving parenting practices; however, it does not reduce blinded ratings of ADHD symptoms. Also after training effects dissipate. This practitioner review proposes steps that can be taken to improve BPT outcomes for ADHD, based on purported causal processes underlying ADHD. The focus is on altered motivational processes (reward and punishment sensitivity), as they closely link to the instrumental processes used in BPT. Following a critical analysis of current behavioral treatments for ADHD, we selectively review motivational reinforcement-based theories of ADHD, including the empirical evidence for the behavioral predictions arising from these theories. This includes consideration of children's emotional reactions to expected and unexpected outcomes. Next we translate this evidence into potential ADHD-specific adjustments designed to enhance the immediate and long-term effectiveness of BPT programs in addressing the needs of children with ADHD. This includes the use of remediation strategies for proposed deficits in learning not commonly used in BPT programs and cautions regarding the use of punishment. Finally, we address how these recommendations can be effectively transferred to clinical practice.

Ubiquinone Levels as a Marker of Antioxidant System in Children with Attention Deficit Hyperactivity Disorder

The aims of this study are to compare serum ubiquinone levels in children with attention deficit hyperactivity disorder (ADHD) with healthy controls and to investigate the correlation between ubiquinone levels of children with ADHD and their ADHD symptoms. Twenty-seven children who are 6-12 years old age with attention deficit hyperactivity disorder having clinically normal intelligence and 23 children with clinically normal intelligence and no psychiatric disorder of similar age and sex who referred to Ankara University School of Medicine Department of Child and Adolescent Psychiatry were included in this study. All children were diagnosed by same researcher using the Semi-Structured Clinical Interview for DSM-IV Scale for Affective Disorders and Schizophrenia Interview for School Children-Now and for the Life-Long Version (K-SADS-PL). Parents and teachers of the children completed the Conners Parent Rating Scale Revised Long Form (CPRS-LF) and Conners Teacher Rating Scale Revised Long Form (CTRS-LF). There were no statistically significant differences regarding the age, gender, and sociodemographic data of the groups. Serum ubiquinone levels of the ADHD group were significantly lower than the control group. We did not find any correlation between ubiquinone levels and clinical values. Since ubiquinone levels are lower in children with ADHD compared with controls, we suggest that decreased antioxidant levels may play a role in ADHD pathogenesis by disrupting oxidative balance.

The relationship between sensory processing sensitivity and attention deficit hyperactivity disorder traits: A spectrum approach

The aim of the present study was to examine the relationship between sensory processing sensitivity (SPS) and symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in adults. The Highly Sensitive Person Scale (HSPS) scale and the Adult ADHD Self-Report Scale (ASRS) were administered to a non-clinical group of 274 participants recruited from a university volunteers list. We found a highly significant positive correlation between number of self-reported ADHD traits and sensory sensitivity. Furthermore, ADHD traits and age were predictors of SPS and exploratory factor analysis revealed a factor that combined ADHD traits and items from the HSPS. The psychometric properties of the HSPS were also examined supporting the unidimensional nature of the concept. To our knowledge, this is the first study to identify a positive relationship between HSPS and ADHD traits in the general population. Our results further support recent findings suggesting abnormal sensory processing in ADHD.

Prevalence and characteristics of South African treatment-seeking patients with substance use disorder and co-occurring attention-deficit/hyperactivity disorder

BACKGROUND

Attention-Deficit/Hyperactivity Disorder (ADHD) constitutes a significant risk factor for the development of Substance Use Disorders (SUDs). Individuals with both conditions use more substances, and the pattern of substance use seems to differ between individuals with and without ADHD.

RESEARCH AIM AND OBJECTIVES

To establish the prevalence of ADHD symptoms in adult South African treatment-seeking patients with SUD, and the pattern of substance use and presence of previous ADHD diagnoses and pharmacotherapy.

METHODS

Adult patients (N = 360) were recruited from rehabilitation facilities and screened using the ADHD Self-Report Scale Symptom Checklist (ASRS-v1.1). Questions included demographics, substance consumption and current/historical use of ADHD-indicated medication.

RESULTS

A third (36.0%) of patients with SUD screened positive for ADHD - 14.6% had been diagnosed with ADHD prior to admission, and indicated pharmacotherapy, while 68.5% of those screened positive were not hitherto diagnosed with ADHD (p < 0.001). A statistical difference was found for polysubstance use with the ADHD group significantly being treated more frequently for use of more than one substance (p = 0.04).

CONCLUSIONS AND IMPLICATIONS

High rates of untreated and unrecognized ADHD were found among treatment-seeking SUD patients. Preventative strategies are crucial to reduce substance use and the development of SUD in individuals affected by ADHD.

Time perception in children with attention deficit-hyperactivity disorder (ADHD): Does task matter? A meta-analysis study

We aimed to assess the effects of the nature of the task on time perception deficit (TPD) in children with attention deficit-hyperactivity disorder (ADHD). The inconsistent results from 12 studies in children with ADHD revealed that the problem of time estimation was more obvious in prospective tasks in long-duration intervals. The modality is not a decisive factor. Only two studies reported the subtypes of ADHD that showed TPD in all subtypes. Children with ADHD have difficulties in time perception (TP). The problem is obvious in different types of modality including visual and auditory, in different types of task time estimation, time reproduction, and especially in longer duration.

Evaluation of causality between ADHD and Parkinson's disease: Mendelian randomization study

In a retrospective cohort study, patients with attention-deficit hyperactivity disorder (ADHD) and psychostimulant prescription were associated with increased risk of Parkinson's disease (PD). It is unclear whether ADHD per se or psychostimulant prescription is associated with PD. We aim to determine if genetic correlation or/and causal association exists between ADHD and PD using summary statistics obtained from the largest meta-analysis of genome-wide association studies of ADHD (20,183 cases; 35,191 controls) and PD (26,421 cases; 442,271 controls). Genetic correlation was tested between ADHD and PD by linkage disequilibrium score regression. Causal estimate was assessed by inverse-variance weighted (IVW) method as the main mendelian randomization analysis, with sensitivity analyses to detect horizontal pleiotropy. Weak and inverse genetic correlation existed between ADHD and PD (r=-0.100;SE=0.045;P = 0.026). Univariable IVW analysis with 10 and 77 genetic instruments respectively revealed null association for ADHD with PD (OR=0.930 per doubling in odds of ADHD; 95% CI:0.792-1.092) and PD with ADHD (OR=0.986 per doubling in odds of PD; 95% CI:0.956-1.015). Multivariable IVW analyses adjusted for BMI/smoking also revealed null association of ADHD with PD. Using 58 PD-associated genetic instruments, multivariable IVW analysis with/without adjustment for BMI/smoking suggested a weak and inverse causal association for PD on ADHD, but cautious interpretation is required. This well-powered study did not support causality between ADHD and PD. The observed positive association between ADHD and PD is more likely to be caused by unmeasured confounders. As psychostimulant use is associated with high risk of early-onset PD, future research should focus on this area.

Determining the association between polymorphisms of the DAT1 and DRD4 genes with attention deficit hyperactivity disorder in children from Java Island

Attention deficit hyperactivity disorder (ADHD) is one of the most common neurobehavioural in the children. Genetic factor is known one of the factors which contributed in ADHD development. VNTR polymorphism in 3'UTR exon 15 of DAT1 gene and exon 3 of DRD4 gene are reported to be associated in ADHD. In this study we examine the association of ADHD with VNTR polymorphism of DAT1 and DRD4 gene in Indonesian children. Sixty-five ADHD children and 70 normal children (6-13 years of age), were included in the study, we matched by age and gender. ADHD was diagnosed by DSM-IV. We performed a casecontrol study to found the association between ADHD and VNTR polymorphism of DAT1 and DRD4 genes. The 10-repeat allele of DAT1 and 2-repeat allele of DRD4 were higher in Indonesian children. Although the frequency of these allele was higher, but it was similar both in ADHD and control groups. Neither DAT1 nor DRD4 gene showed showed significant difference in genotype distribution and frequency allele between both groups (p > 0.05). No association between ADHD and VNTR polymorphism of DAT1 and DRD4 genes found in Indonesian children. This data suggest that DAT1 and DRD4 do not contribute to etiology of ADHD in Indonesian children. Further studies are needed to clarify association between VNTR polymorphism of DAT1 and DRD4 genetic with ADHD of Indonesian children in larger sample size and family based study.

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.

The influence of attractiveness and convenience cues on food appeal in adults with and without ADHD

OBJECTIVE

Previous research on adults with ADHD revealed high rates of overweight and obesity, as well as unhealthy diet habits. Other studies demonstrated that social-affective contexts can influence food choice. This study examines the sensitivity of adults with ADHD to cues of food attractiveness and convenience, for healthy and unhealthy foods.

METHOD

One hundred and seventy-two university students with (n = 59) and without (n = 113) ADHD, aged 19-40, participated in the study. Participants rated the level of appeal of 32 pictures of healthy and unhealthy foods, which varied in the degree of attractiveness and convenience.

RESULTS

The findings reveal a higher level of appeal of attractive food items compared to non-attractive ones (p < .001), as well as of convenient compared to non-convenient food items (p = .005). Type of diagnostic group did not have an effect on the level of appeal.

CONCLUSION

Increasing the attractiveness and convenience of food items increased the level of appeal for both students with and without ADHD. These findings emphasize the importance of environmental health intervention to potentially reduce abnormal eating pattern in the ADHD adult population, which may contribute in preventing the reported higher risk of obesity in this population.

Neurofeedback in ADHD: A qualitative study of strategy use in slow cortical potential training

Neurofeedback (NF) as a treatment for children and adolescents with attention deficit hyperactivity disorder (ADHD) has gained growing interest in recent years. Most research has been quantitative, focusing on treatment outcomes, while qualitative approaches exploring the treatment process and participants’ experiences are scarce. The objective of this study was to examine NF participants’ use of cognitive and other strategies for approaching and solving NF tasks, their development over the course of the training and the influence of participants’ compliance.

Recognition of emotional facial expressions in adolescents with attention deficit/hyperactivity disorder

INTRODUCTION

Attention Deficit/Hyperactivity Disorder (ADHD) is associated with impaired social competencies, due in part to an inability to determine emotional states through facial expressions. Social interactions are a critical component of adolescence, which raises the question of how do adolescents with ADHD cope with this impairment. Yet, previous reviews do not distinguish between children and adolescents. This review focuses on the ability of adolescents (defined by the World Health Organization as 10-19 years old) with ADHD to recognize emotional facial expressions, when compared to their typically-developing peers.

METHODS

Comprehensive database search and analysis yielded 9 relevant studies published between 2008 and 2018.

RESULTS

The studies reviewed here examined recognition of emotional facial expressions in adolescents with ADHD. Behavioral measures (reaction time, reaction time variance and recognition accuracy) show no statistically significant differences between adolescents with ADHD and their typically-developing peers. However, neural responses as recorded using functional Magnetic Resonance Imaging (fMRI) or Event Related Potentials (ERP) find differences in brain activity and the temporal evolution of the reaction between the two groups.

CONCLUSIONS

Studies of children and of adults with ADHD find deficiencies in the recognition of emotional facial expressions. However, this review shows that adolescents with ADHD perform comparably to their peers on accuracy and rate, although their neural processing is different. This suggests that the methodologies employed by the ADHD and typically-developing adolescents to asses facial expressions are different. Further study is needed to determine what these may be.

Acoustic closed-loop stimulation during sleep improves consolidation of reward-related memory information in healthy children but not in children with attention-deficit hyperactivity disorder

Study Objectives

Slow oscillations (SO) during slow-wave sleep foster the consolidation of declarative memory. Children with attention-deficit hyperactivity disorder (ADHD) display deficits in the sleep-associated consolidation of declarative memory, possibly due to an altered function of SO. The present study aimed at enhancing SO activity using closed-looped acoustic stimulation during slow-wave sleep in children with ADHD.

Methods

A total of 29 male children (14 with ADHD; aged 8–12 years) participated in a double-blind, placebo-controlled study trial. Children spent two experimental nights in a sleep lab, one stimulation night and one sham night. A declarative learning task (word-pair learning) with a reward condition was used as a primary outcome. Secondary outcome variables were a procedural memory (serial reaction time) and working memory (WM; n-back) task. Encoding of declarative and procedural memory took place in the evening before sleep. After sleep, the retrieval took place followed by the n-back task.

Results

The stimulation successfully induced SO activity during sleep in children with and without ADHD. After stimulation, only healthy children performed better on high-rewarded memory items (primary outcome). In contrast, there were indications that only children with ADHD benefitted from the stimulation with respect to procedural as well as WM performance (secondary outcome).

Conclusions

We were able to show that the acoustic closed-loop stimulation can be applied to enhance SO activity in children with and without ADHD. Our data indicate that SO activity during sleep interacts with subsequent memory performance (primary outcome: rewarded declarative memory; secondary outcome: procedural and WM) in children with and without ADHD.