Beyond DSM: the role of auditory processing in attention and its disorders

Associative gene networks reveal novel candidates important for ADHD and dyslexia comorbidity

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is commonly associated with developmental dyslexia (DD), which are both prevalent and complicated pediatric neurodevelopmental disorders that have a significant influence on children's learning and development. Clinically, the comorbidity incidence of DD and ADHD is between 25 and 48%. Children with DD and ADHD may have more severe cognitive deficiencies, a poorer level of schooling, and a higher risk of social and emotional management disorders. Furthermore, patients with this comorbidity are frequently treated for a single condition in clinical settings, and the therapeutic outcome is poor. The development of effective treatment approaches against these diseases is complicated by their comorbidity features. This is often a major problem in diagnosis and treatment. In this study, we developed bioinformatical methodology for the analysis of the comorbidity of these two diseases. As such, the search for candidate genes related to the comorbid conditions of ADHD and DD can help in elucidating the molecular mechanisms underlying the comorbid condition, and can also be useful for genotyping and identifying new drug targets.

RESULTS

Using the ANDSystem tool, the reconstruction and analysis of gene networks associated with ADHD and dyslexia was carried out. The gene network of ADHD included 599 genes/proteins and 148,978 interactions, while that of dyslexia included 167 genes/proteins and 27,083 interactions. When the ANDSystem and GeneCards data were combined, a total of 213 genes/proteins for ADHD and dyslexia were found. An approach for ranking genes implicated in the comorbid condition of the two diseases was proposed. The approach is based on ten criteria for ranking genes by their importance, including relevance scores of association between disease and genes, standard methods of gene prioritization, as well as original criteria that take into account the characteristics of an associative gene network and the presence of known polymorphisms in the analyzed genes. Among the top 20 genes with the highest priority DRD2, DRD4, CNTNAP2 and GRIN2B are mentioned in the literature as directly linked with the comorbidity of ADHD and dyslexia. According to the proposed approach, the genes OPRM1, CHRNA4 and SNCA had the highest priority in the development of comorbidity of these two diseases. Additionally, it was revealed that the most relevant genes are involved in biological processes related to signal transduction, positive regulation of transcription from RNA polymerase II promoters, chemical synaptic transmission, response to drugs, ion transmembrane transport, nervous system development, cell adhesion, and neuron migration.

CONCLUSIONS

The application of methods of reconstruction and analysis of gene networks is a powerful tool for studying the molecular mechanisms of comorbid conditions. The method put forth to rank genes by their importance for the comorbid condition of ADHD and dyslexia was employed to predict genes that play key roles in the development of the comorbid condition. The results can be utilized to plan experiments for the identification of novel candidate genes and search for novel pharmacological targets.

Musical Performance in Adolescents with ADHD, ADD and Dyslexia—Behavioral and Neurophysiological Aspects

Research has shown that dyslexia and attention deficit (hyperactivity) disorder (AD(H)D) are characterized by specific neuroanatomical and neurofunctional differences in the auditory cortex. These neurofunctional characteristics in children with ADHD, ADD and dyslexia are linked to distinct differences in music perception. Group-specific differences in the musical performance of patients with ADHD, ADD and dyslexia have not been investigated in detail so far. We investigated the musical performance and neurophysiological correlates of 21 adolescents with dyslexia, 19 with ADHD, 28 with ADD and 28 age-matched, unaffected controls using a music performance assessment scale and magnetoencephalography (MEG). Musical experts independently assessed pitch and rhythmic accuracy, intonation, improvisation skills and musical expression. Compared to dyslexic adolescents, controls as well as adolescents with ADHD and ADD performed better in rhythmic reproduction, rhythmic improvisation and musical expression. Controls were significantly better in rhythmic reproduction than adolescents with ADD and scored higher in rhythmic and pitch improvisation than adolescents with ADHD. Adolescents with ADD and controls scored better in pitch reproduction than dyslexic adolescents. In pitch improvisation, the ADD group performed better than the ADHD group, and controls scored better than dyslexic adolescents. Discriminant analysis revealed that rhythmic improvisation and musical expression discriminate the dyslexic group from controls and adolescents with ADHD and ADD. A second discriminant analysis based on MEG variables showed that absolute P1 latency asynchrony |R-L| distinguishes the control group from the disorder groups best, while P1 and N1 latencies averaged across hemispheres separate the control, ADD and ADHD groups from the dyslexic group. Furthermore, rhythmic improvisation was negatively correlated with auditory-evoked P1 and N1 latencies, pointing in the following direction: the earlier the P1 and N1 latencies (mean), the better the rhythmic improvisation. These findings provide novel insight into the differences between music processing and performance in adolescents with and without neurodevelopmental disorders. A better understanding of these differences may help to develop tailored preventions or therapeutic interventions.

Practitioner's review: medication for children and adolescents with autism spectrum disorder (ASD) and comorbid conditions

Alleviating the multiple problems of children with autism spectrum disorder (ASD) and its comorbid conditions presents major challenges for the affected children, parents, and therapists. Because of a complex psychopathology, structured therapy and parent training are not always sufficient, especially for those patients with intellectual disability (ID) and multiple comorbidities. Moreover, structured therapy is not available for a large number of patients, and pharmacological support is often needed, especially in those children with additional attention deficit/hyperactivity and oppositional defiant, conduct, and sleep disorders.

Benign rolandic epilepsy of childhood and central auditory processing disorder: A noncasual neurophysiological association

PURPOSE

The purpose of this study was to demonstrate the association between benign rolandic epilepsy of childhood (BREC) and central auditory processing disorders (CAPDs) and to test the hypothesis that an early onset of BREC could be associated with more cases of CAPD.

METHOD

This study has a retrospective cross-sectional design conducted from January 2006 to January 2016 including 93 patients with BREC and without intellectual disability, dyslexia, and attention-deficit hyperactivity disorders. All patients were evaluated for central auditory processing (CAP), and its presence or absence was compared with age of seizure onset.

RESULTS

In all patients, audiometric test results were normal, and in 43 cases (46.2%), CAPD was detected. There was no significant statistical difference in the mean age of seizure onset.

CONCLUSION

A significant proportion of children with BREC will have a diagnosis of CAPD at school age.

Le TDAH chez les enfants et les adolescents, partie 1 : l’étiologie, le diagnostic et la comorbidité

Le trouble de déficit de l’attention/hyperactivité (TDAH) est un trouble neurodéveloppemental chronique. La Société canadienne de pédiatrie a préparé trois documents de principes après avoir effectué des analyses bibliographiques systématiques. Leurs objectifs s’établissent comme suit : 1) Résumer les données probantes cliniques à jour sur le TDAH. 2) Établir une norme pour les soins du TDAH. 3) Aider les cliniciens canadiens à prendre des décisions éclairées et fondées sur des données probantes pour rehausser la qualité des soins aux enfants et aux adolescents qui présentent cette affection.

Les thèmes abordés dans la partie 1, qui est axée sur le diagnostic, incluent la prévalence, la génétique, la physiopathologie, le diagnostic différentiel, ainsi que les troubles psychiatriques et les troubles du développement comorbides. En plus des recherches dans les bases de données, les auteurs ont analysé les directives les plus récentes de l’American Academy of Pediatrics , de l’American Academy of Child and Adolescent Psychiatry , du National Institute for Health and Clinical Excellence , du Scottish Intercollegiate Guidelines Network et de l’Eunethydis European ADHD Guidelines Group . Puisque le TDAH est un trouble hétérogène, son évaluation médicale complète devrait toujours inclure une anamnèse fouillée, un examen physique et une évaluation approfondie du diagnostic différentiel et des comorbidités connexes. Les auteurs proposent des recommandations précises sur la récolte d’information, les tests à effectuer et les orientations vers divers services.

ADHD in children and youth: Part 1-Etiology, diagnosis, and comorbidity

Attention-deficit hyperactivity disorder (ADHD) is a chronic neurodevelopmental disorder. Three position statements have been developed by the Canadian Paediatric Society, following systematic literature reviews. Statement objectives are to: 1) Summarize the current clinical evidence regarding ADHD,2) Establish a standard for ADHD care, and3) Assist Canadian clinicians in making well-informed, evidence-based decisions to enhance care of children and youth with this condition. Specific topics reviewed in Part 1, which focuses on diagnosis, include: prevalence, genetics, pathophysiology, differential diagnosis and comorbid psychiatric disorders and developmental disorders. In addition to database searches, the most recent guidelines of the American Academy of Pediatrics, the American Academy of Child and Adolescent Psychiatry, the National Institute for Health and Clinical Excellence, the Scottish Intercollegiate Guidelines Network, and the Eunethydis European ADHD Guidelines Group, were reviewed. Because ADHD is a heterogeneous disorder, comprehensive medical assessment for ADHD should always include a complete history, a physical examination, and a thorough consideration of differential diagnosis and related comorbidities. Specific recommendations for information gathering, testing, and referral are offered.

Response to the Letter to the Editor From Moncrieff (2017) Regarding de Wit et al. (2016), "Characteristics of Auditory Processing Disorders: A Systematic Review"

PURPOSE

The purpose of this letter is to respond to Moncrieff's (2017) letter to the editor, "Response to de Wit et al., 2016, 'Characteristics of Auditory Processing Disorders: A Systematic Review,'" published in May 2017 by the Journal of Speech, Language, and Hearing Research.

CONCLUSION

We believe that our original conclusions are valid given the limited evidence that is currently available about the etiology of auditory processing disorders (APD). The focus of our systematic review was to identify the characteristics of children with a diagnosis of APD or a suspicion of APD. The results of our study showed that the characteristics of these children are not specific or limited to the auditory modality but are multimodal instead. In our view, it is incorrect to use the diagnosis APD, because there is not necessarily a specific auditory deficit in a large group of children suffering from listening difficulties. Before we start using any new diagnoses, a better insight into how bottom-up and top-down processes are precisely involved in listening needs to be developed. In addition, more insight is needed with respect to the similarities and differences between the different developmental disorders of children.

Systematic Review of the Effectiveness of Frequency Modulation Devices in Improving Academic Outcomes in Children With Auditory Processing Difficulties

This systematic review describes the published evidence related to the effectiveness of frequency modulation (FM) devices in improving academic outcomes in children with auditory processing difficulties. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards were used to identify articles published between January 2003 and March 2014. The Cochrane Population, Intervention, Control, Outcome, Study Design approach and the American Occupational Therapy Association process forms were used to guide the article selection and evaluation process. Of the 83 articles screened, 7 matched the systematic review inclusion criteria. Findings were consistently positive, although limitations were identified. Results of this review indicate moderate support for the use of FM devices to improve children's ability to listen and attend in the classroom and mixed evidence to improve specific academic performance areas. FM technology should be considered for school-age children with auditory processing impairments who are receiving occupational therapy services to improve functioning in the school setting.

Atypical Bilateral Brain Synchronization in the Early Stage of Human Voice Auditory Processing in Young Children with Autism

Autism spectrum disorder (ASD) has been postulated to involve impaired neuronal cooperation in large-scale neural networks, including cortico-cortical interhemispheric circuitry. In the context of ASD, alterations in both peripheral and central auditory processes have also attracted a great deal of interest because these changes appear to represent pathophysiological processes; therefore, many prior studies have focused on atypical auditory responses in ASD. The auditory evoked field (AEF), recorded by magnetoencephalography, and the synchronization of these processes between right and left hemispheres was recently suggested to reflect various cognitive abilities in children. However, to date, no previous study has focused on AEF synchronization in ASD subjects. To assess global coordination across spatially distributed brain regions, the analysis of Omega complexity from multichannel neurophysiological data was proposed. Using Omega complexity analysis, we investigated the global coordination of AEFs in 3–8-year-old typically developing (TD) children (n = 50) and children with ASD (n = 50) in 50-ms time-windows. Children with ASD displayed significantly higher Omega complexities compared with TD children in the time-window of 0–50 ms, suggesting lower whole brain synchronization in the early stage of the P1m component. When we analyzed the left and right hemispheres separately, no significant differences in any time-windows were observed. These results suggest lower right-left hemispheric synchronization in children with ASD compared with TD children. Our study provides new evidence of aberrant neural synchronization in young children with ASD by investigating auditory evoked neural responses to the human voice.

Cognitive impairments are different in single-incidence and multi-incidence ADHD families

BACKGROUND

We may improve our understanding of the role of common versus unique risk factors in attention-deficit/hyperactivity disorder (ADHD) by examining ADHD-related cognitive deficits in single- (SPX), and multi-incidence (MPX) families. Given that individuals from multiplex (MPX) families are likely to share genetic vulnerability for the disorder, whereas simplex (SPX) ADHD may be the result of sporadic (non-)genetic causes unique to the patient, we hypothesized that cognitive impairments may be different in SPX and MPX ADHD as indicated by (a) the presence of cognitive deficits in MPX, but not SPX unaffected siblings and (b) dissimilar cognitive profiles in SPX and MPX ADHD patients.

METHODS

Tasks measuring total IQ, verbal attention, executive functioning, motor functioning, and time estimation were administered to 31 SPX/264 MPX ADHD probands, 47 SPX/123 MPX unaffected siblings, and 263 controls, aged 6-19 years.

RESULTS

SPX unaffected siblings were unimpaired compared to controls, except for verbal working memory, whereas MPX unaffected siblings showed impairments on most cognitive domains. The cognitive profiles of SPX and MPX probands were highly similar, except that verbal attention, response inhibition and motor control deficits were more pronounced in MPX probands, and -compared to their unaffected siblings- impairments in IQ, visual working memory and timing abilities were more pronounced in SPX cases.

CONCLUSIONS

Our results support the hypothesis that a partly different cognitive architecture may underlie SPX and MPX forms of ADHD, which becomes evident when contrasting cognitive performances within families. Cognitive factors underlying MPX forms of ADHD are familial, whereas nonfamilial in SPX ADHD. SPX-MPX stratification may be a step forward in unraveling diverse causal pathways.

Size and synchronization of auditory cortex promotes musical, literacy, and attentional skills in children

Playing a musical instrument is associated with numerous neural processes that continuously modify the human brain and may facilitate characteristic auditory skills. In a longitudinal study, we investigated the auditory and neural plasticity of musical learning in 111 young children (aged 7-9 y) as a function of the intensity of instrumental practice and musical aptitude. Because of the frequent co-occurrence of central auditory processing disorders and attentional deficits, we also tested 21 children with attention deficit (hyperactivity) disorder [AD(H)D]. Magnetic resonance imaging and magnetoencephalography revealed enlarged Heschl's gyri and enhanced right-left hemispheric synchronization of the primary evoked response (P1) to harmonic complex sounds in children who spent more time practicing a musical instrument. The anatomical characteristics were positively correlated with frequency discrimination, reading, and spelling skills. Conversely, AD(H)D children showed reduced volumes of Heschl's gyri and enhanced volumes of the plana temporalia that were associated with a distinct bilateral P1 asynchrony. This may indicate a risk for central auditory processing disorders that are often associated with attentional and literacy problems. The longitudinal comparisons revealed a very high stability of auditory cortex morphology and gray matter volumes, suggesting that the combined anatomical and functional parameters are neural markers of musicality and attention deficits. Educational and clinical implications are considered.