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A recent genome-wide association study (GWAS) identified 12 independent loci significantly associated with attention-deficit/hyperactivity disorder (ADHD). Polygenic risk scores (PRS), derived from the GWAS, can be used to assess genetic overlap between ADHD and other traits. Using ADHD samples from several international sites, we derived PRS for ADHD from the recent GWAS to test whether genetic variants that contribute to ADHD also influence two cognitive functions that show strong association with ADHD: attention regulation and response inhibition, captured by reaction time variability (RTV) and commission errors (CE).
The discovery GWAS included 19 099 ADHD cases and 34 194 control participants. The combined target sample included 845 people with ADHD (age: 8–40 years). RTV and CE were available from reaction time and response inhibition tasks. ADHD PRS were calculated from the GWAS using a leave-one-study-out approach. Regression analyses were run to investigate whether ADHD PRS were associated with CE and RTV. Results across sites were combined via random effect meta-analyses.
When combining the studies in meta-analyses, results were significant for RTV (R2 = 0.011, β = 0.088, p = 0.02) but not for CE (R2 = 0.011, β = 0.013, p = 0.732). No significant association was found between ADHD PRS and RTV or CE in any sample individually (p > 0.10).
We detected a significant association between PRS for ADHD and RTV (but not CE) in individuals with ADHD, suggesting that common genetic risk variants for ADHD influence attention regulation.
As children with attention-deficit/hyperactivity disorder (ADHD) usually show psychopathological signs beyond their core symptoms (e.g. elevated scores of the dysregulation profile (DP) in 30–40%), treatments with a broader approach to self-regulation skills may be supportive. Neurofeedback (NF) may reflect such an option. Aim of the present analysis was to compare the effects of slow cortical potential (SCP) NF and θ/β NF on the DP using data from a previous trial.
Thirty children with ADHD (aged 8–12 years) and a DP score in the Strengths and Difficulties Questionnaire (SDQ-DP) ⩾ 3 were included. NF treatment consisted of one block of SCP NF and one block of θ/β NF (18 units per block) allowing an intraindividual comparison. Effects of the NF protocols were also contrasted to a control group (n = 18) that completed an attention skills training (between-group analysis).
Regarding the SDQ-DP, SCP NF was superior to θ/β NF and the control condition. Effects of SCP NF and θ/β NF on ADHD symptom severity were not significantly different. The SDQ-DP score did not correlate with EEG-related measures previously found to be predictors for SCP NF on ADHD symptoms.
SCP NF may reflect a more general approach to improve cognitive, emotional and behavioral self-regulation skills. If confirmed in a larger sample, the SDQ-DP score could be used as an indication criterion and contribute to the individualization of NF in ADHD. Overall, the differential effect provides further evidence for the specificity of NF effects.
The closeness of somatosensory phenomena and emotional states can be critically extended into a clinical perspective by referring to Tourette's Syndrome (TS). Two examples are discussed in this commentary: (1) the neurodevelopmental approach to the pre- and post-tic sensorimotor urges, and (2) the TS treatment with deep brain stimulation. It is shown that in TS, both views (locationist and constructionist) need to be combined along the lifespan in order to get a more realistic picture of the brain basis of emotion.
Developmental, epidemiological, and neurobiological studies indicate that the adaptive and maladaptive functions, as well as immediate and long-term consequences of drug use, may vary by age. Early initiation seems to be associated with a reduced ability to use drugs purposely in a temporally stable, non-addictive manner. Prevention strategies should consider social environmental factors and aim to delay age at initiation.
In developmental psychopathology, differentiating between the coexistence and the clinical entity of two problem areas is of utmost importance. So far, logistic regression analysis has already provided helpful answers, as shown in studies on comorbidity of tic disorders. While the concept of bridging symptoms may be investigated adequately by both logistic regression and the network approach, the former (latent variable) seems to be of advantage with regard to the problems of multiple comorbidities and development.
Cramer et al.'s network approach reconceptualizes mental comorbidity on the basis of symptom space originating from psychometric signatures. We argue that the advantages of this approach need to be regarded in the context of the multi-level functional organization of the neural substrate, ranging from neurogenetic to psychometric. Neuroelectric oscillations are proposed as a level-integrating principle.
Erickson's article links the concept of four “basic” tastes to color perception as a sensory modality with similar problems of categorization. Such problems are also present for odors and olfaction. Olfaction is the sensory modality with the closest physical relationship to taste, and the sense organs of both permanently interact. We discuss the origins and influences of core ideas of the science of smell to add to the discussion of unresolved categorization problems in taste from another, closely related point of view.
Reaction time (RT) variability is one of the strongest findings to emerge in cognitive-experimental research of attention deficit hyperactivity disorder (ADHD). We set out to confirm the association between ADHD and slow and variable RTs and investigate the degree to which RT performance improves under fast event rate and incentives. Using a group familial correlation approach, we tested the hypothesis that there are shared familial effects on RT performance and ADHD.
A total of 144 ADHD combined-type probands, 125 siblings of the ADHD probands and 60 control participants, ages 6–18, performed a four-choice RT task with baseline and fast-incentive conditions.
ADHD was associated with slow and variable RTs, and with greater improvement in speed and RT variability from baseline to fast-incentive condition. RT performance showed shared familial influences with ADHD. Under the assumption that the familial effects represent genetic influences, the proportion of the phenotypic correlation due to shared familial influences was estimated as 60–70%.
The data are inconsistent with models that consider RT variability as reflecting a stable cognitive deficit in ADHD, but instead emphasize the extent to which energetic or motivational factors can have a greater effect on RT performance in ADHD. The findings support the role of RT variability as an endophenotype mediating the link between genes and ADHD.
Tourette Syndrome (TS) and Obsessive-Compulsive Disorder (OCD) are highly associated and often it is difficult to differentiate their symptomatology. In TS, habit forming neuronal systems may form habits of their own sometimes similar to ritualized behavior. However, whereas in OCD merely the affect-loop is touched, in TS the sensorimotor-loop plays the major role, although some overlap can be seen in the clinical spectrum between TS and OCD. The latter is mainly related to the just-right phenomenon which shows a clear developmental course. An analogous behavioral model for TS and OCD with reference to just-right is suggested.
First-onset tics during stimulant treatment of attention-deficit–hyperactivity disorder (ADHD) are clinically relevant and remain a matter of scientific debate. Because there are limited clinical trials analyzing the risk of first-onset tics in stimulant-treated ADHD, a comprehensive evaluation is required for evidence-based clinical recommendations. An analysis of studies with high methodological quality (i.e. double-blind placebo-controlled) on first-onset tics during stimulant treatment of ADHD revealed that there seems to be no elevated risk of first-onset tics in children undergoing this treatment. Although a close temporal relationship might be seen in a few patients, the role of treatment duration, dose of stimulant, genetic vulnerability, and developmental aspects need to be further explored to clarify possible pathophysiological mechanisms of tic emergence under stimulant treatment. The results of high quality studies, in addition to specialized studies with methodological limitations, suggest that stimulants are the criterion standard for the safe and successful treatment of ADHD.
Aribert Rothenberger, Department of Child and Adolescent Psychiatry, University of Göttingen, Germany,
Tobias Banaschewski, Department of Child and Adolescent Psychiatry, University of Göttingen, Germany
Usually, tic disorders have their onset around school entry and in many cases they develop into a complex neuropsychiatric disorder with a high variety of associated problems. Only about 15 per cent of cases remain with their tics only. On the other hand, there is a tendency of spontaneous remission of tics after adolescence. Hence, refined developmental psychopathological knowledge is necessary to diagnose and treat the patients in an adequate manner.
The interaction of tic expression with stress sensitivity and tic awareness is another point of practical relevance. Although the background of tic disorders has been the subject of ignorance and speculations for at least the past 300 years, today we accept genetic, neurodynamic and psychological factors as well as their interplay. All of these have to be assessed in each individual case concerning tic control.
Finally, knowledge of the short-term and long-term spontaneous temporal patterning of tics is important for the clinician, because it informs decisions about when to initiate anti-tic interventions, when to change drugs and when to be patient and simply provide close monitoring and support to the family to cope with the psychosocial problems.
Definition and classification
The main features of tic disorders are:
motor and/or vocal tics (see Table 21.1)
begin in proximal areas (head, face, neck)
occurrence of tics many times a day (every day or intermittently; waxing and waning)
duration of tics from 4 weeks to more than 1 year
suppressibility of some tics for a short period of time (after the age of 10 years)
premonitory sensorimotor sensations before tics (after the age of 10 years)
Early and automatic neuropsychological processes may be influenced by altered dopaminergic functions but cannot be fully explained by these or by altered reinforcement and extinction processes. The reinforcement- extinction model is excellent for understanding certain causal pathways of attention-deficit/hyperactivity disorder (ADHD), but it can hardly explain the heterogeneous developmental trajectories of ADHD fully. It should be integrated into a multiple pathways model.
Sleep disturbances are common for children with attentiondeficit/ hyperactivity disorder (ADHD) and are of great clinical significance. Brain dopamine plays an important role for both ADHD symptoms and sleep-wake regulation. We therefore suggest that one basic aspect of integrative brain-behavior relationship such as the sleep-wake cycle may certainly be addressed in a dynamic developmental theory of ADHD.
Since 1994, child and adolescent psychiatry has been a distinct specialty, separate from psychiatry, within the Union of European Medical Specialists (UEMS). It has a slightly curious title, of which more later. It has proved a successful arena for promoting training, and this in turn has led to a developing European view of what exactly child and adolescent psychiatry is, and how it can be practised. This article tries to reflect this.
Although premonitory sensory phenomena (PSP) and suppressibility of tics (SPT) are important in Tourette syndrome not only when behavioural therapeutic approaches in children are considered, there is a lack of developmental information on these phenomena. Therefore, a cross-sectional survey of these factors in children and adolescents was carried out. Rates of PSP and SPT were gathered using a questionnaire for the assessment of Tourette syndrome. The 254 outpatients (212 males, 42 females) with Tourette syndrome investigated had an age range of 8 to 19 years, normal intelligence, and diagnosis according to DSM-IV-TR/ICD-10. To test for developmental effects, the total group was stratified into three age groups (8 to 10, 11 to 14, and 15 to 19 years). Data were statistically evaluated using χ2 tests. Of the 254 participants, 37% reported PSP, while 64% were able to suppress their tics. Only a subgroup of 119 patients gave unequivocal answers to both questions and only 60% of these experienced both PSP and SPT. Statistically significant stepwise increases were found at two different age levels. One was around 10 years (PSP ‘Yes’ or ‘No’ and SPT), the other around age 14 (PSP ‘Yes’). There was no influence of tic duration and age at tic onset on PSP/SPT. The reported data suggest that PSP is experienced rarely in younger children with Tourette syndrome and is not a necessary prerequisite for SPT. Increasing PSP with age merely seems to reflect cognitive development rather than intrinsic aspects of Tourette syndrome. In children under 10 years of age, SPT might require more awareness of tics than in older age groups. Developmental aspects of PSP and SPT should be taken into consideration when studies of cognitive behavioural treatment for children and adolescents with Tourette syndrome are planned.
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