Differential association between MAOA, ADHD and neuropsychological functioning in boys and girls

Contains fulltext : 70148.pdf (publisher's version ) (Closed access)Attention-deficit/hyperactivity disorder (ADHD) is more common in boys than in girls. It has been hypothesized that this sex difference might be related to genes on the X-chromosome, like Monoamine Oxidase A (MAOA). Almost all studies on the role of MAOA in ADHD have focused predominantly on boys, making it unknown whether MAOA also has an effect on ADHD in girls, and few studies have investigated the relationship between MAOA and neuropsychological functioning, yet this may provide insight into the pathways leading from genotype to phenotype. The current study set out to examine the relationship between MAOA, ADHD, and neuropsychological functioning in both boys (265 boys with ADHD and 89 male non-affected siblings) and girls (85 girls with ADHD and 106 female non-affected siblings). A haplotype was used based on three single nucleotide polymorphisms (SNPs) (rs12843268, rs3027400, and rs1137070). Two haplotypes (GGC and ATT) captured 97% of the genetic variance in the investigated MAOA SNPs. The ATT haplotype was more common in non-affected siblings (P = 0.025), conferring a protective effect for ADHD in both boys and girls. The target and direction of the MAOA effect on neuropsychological functioning was different in boys and girls: The ATT haplotype was associated with poorer motor control in boys (P = 0.002), but with better visuo-spatial working memory in girls (P = 0.01). These findings suggest that the genetic and neuropsychological mechanisms underlying ADHD may be different in boys and girls and underline the importance of taking into account sex effects when studying ADHD

Substance use disorders in adolescents with attention deficit hyperactivity disorder: a 4-year follow-up study

Aim To examine the relationship between a childhood diagnosis of attention deficit hyperactivity disorder (ADHD) with or without oppositional defiant disorder (ODD)/conduct disorder (CD) and the development of later alcohol/drug use disorder [psychoactive substance use disorder (PSUD)] and nicotine dependence in a large European sample of ADHD probands, their siblings and healthy control subjects. Participants design and settingSubjects (n=1017) were participants in the Belgian, Dutch and German part of the International Multicenter ADHD Genetics (IMAGE) study. IMAGE families were identified through ADHD probands aged 5-17 years attending out-patient clinics, and control subjects from the same geographic areas. After a follow-up period (mean: 4.4 years) this subsample was re-assessed at a mean age of 16.4 years. Measurements PSUD and nicotine dependence were assessed using the Diagnostic Interview Schedule for Children, Alcohol Use Disorders Identification Test, Drug Abuse Screening Test and Fagerstrom test for Nicotine Dependence. Findings The ADHD sample was at higher risk of developing PSUD [hazard ratio (HR)=1.77, 95% confidence interval (CI)=1.05-3.00] and nicotine dependence (HR=8.61, 95% CI=2.44-30.34) than healthy controls. The rates of these disorders were highest for ADHD youth who also had CD, but could not be accounted for by this comorbidity. We did not find an increased risk of developing PSUD (HR=1.18, 95% CI=0.62-2.27) or nicotine dependence (HR=1.89, 95% CI=0.46-7.77) among unaffected siblings of ADHD youth. Conclusions A childhood diagnosis of attention deficit hyperactivity disorder is a risk factor for psychoactive substance use disorder and nicotine dependence in adolescence and comorbid conduct disorder, but not oppositional defiant disorder, further increases the risk of developing psychoactive substance use disorder and nicotine dependence

A review and analysis of the relationship between neuropsychological measures and DAT1 in ADHD

Contains fulltext : 69105.pdf (publisher's version ) (Closed access)Meta-analyses indicate that the gene coding for the dopamine transporter (DAT1 or SLC6A3) is associated with an increased risk for ADHD. The mechanisms of this gene for ADHD are unclear. We systematically reviewed studies linking the VNTR in the 3' UTR of the DAT1 to neurophysiological and neuropsychological measures. In addition, a broad set of executive/cognitive and motor tests was administered to 350 children (5-11 years) and adolescents (11-19 years) with ADHD and 195 non-affected siblings. Two VNTRs (in intron 8 and the 3' UTR) and four SNPs (two 5' and two 3') in DAT1 were genotyped. The effect of the polymorphisms on neuropsychological functioning was studied. The review indicated that the majority of studies did not find a relation between DAT1 and neurophysiological or neuropsychological measures. In our sample, several of the polymorphisms of DAT1 were associated with ADHD and ADHD was associated with impaired neuropsychological functioning. However, none of the DAT1 polymorphisms was convincingly associated with neuropsychological dysfunctioning. This suggests that the effect of DAT1 on ADHD was not mediated by neuropsychological performance. However, since DAT1 is mainly expressed in the striatum and not the prefrontal cortex, it may influence striatum-related functions (such as delay aversion) more heavily than prefrontal related functions (such as executive functions). Associations of DAT1 with ADHD were only found in adolescents, which may suggest that DAT1 mainly exerts its effect in adolescence, and/or that having a more persistent form of ADHD may mark a more severe or homogeneous genetic form of the disorder

Реалізація органами влади Автономної Республіки Крим та органами місцевого самоврядування повноважень у сфері адміністративно-територіального устрою України

Досліджено практику реалізації органами влади Автономної Республіки Крим та органами місцевого самоврядування повноважень у сфері адміністративно-територіального устрою України.Исследуется практика реализации органами власти Автономной Республики Крым и органами местного самоуправления полномочий в сфере административно-территориального устройства Украины.The article is devoted to the research of practical realization of powers by the official bodies of Autonomous Republic of Crimea and local self-government bodies in the sphere of Ukrainian administrative-territorial system

DOF phase separation of the Lennard-Jones fcc(111) surface

Recent lattice model calculations have suggested that a full-layered crystal surface may undergo, under canonical (particle-conserving) conditions, a preroughening-driven two-dimensional phase separation into two disordered flat (DOF) regions, of opposite order parameter. We have carried out extensive classical molecular dynamics (MD) simulations of the Lennard-Jones fcc(111) surface, to check whether these predictions are relevant or not for a realistic continuous system. Very long simulation times, a grid of temperatures from (2/3)Tm to Tm, and unusually large system sizes are employed to ensure full equilibrium and good statistics. By examining layer-by-layer occupancies, height fluctuations, sublattice order parameter and X-ray structure factors, we find a clear anomaly at ~0.83Tm. The anomaly is distinct from roughening (whose incipiency is also detected at ~0.94Tm), and is seen to be consistent with the preroughening plus phase separation scenario.Comment: REVTeX, 8 pages, 4 figures; new figure showing simulation snapshots added; reference updated and other minor change

Oculomotor capture in ADHD

It is generally thought that deficits in response inhibition form an important area of dysfunction in patients with attention-deficit/ hyperactivity disorder (ADHD). However, recent research using visual search paradigms seems to suggest that these inhibitory deficits do not extend towards inhibiting irrelevant distractors. Using an oculomotor capture task, the present study investigated whether boys with ADHD and their nonaffected brothers are impaired in suppressing reflexive eye movements to a task-irrelevant onset distractor. Results showed that boys with ADHD had slower responses than controls, but were as accurate in their eye movements as controls. Nonaffected brothers showed similar problems in the speed of responding as their affected brothers, which might suggest that this deficit relates to a familial risk for developing the disorder. Importantly, all three groups were equally captured by the distractor, which shows that boys with ADHD and their brothers are not more distracted by the distractor than are controls. Saccade latency and the proportion of intrusive saccades were related to continuous dimensions of ADHD symptoms, which suggests that these deficits are not simply present or absent, but rather indicate that the severity of these deficits relate to the severity of ADHD. The finding that boys with ADHD (and their nonaffected brothers) did not have problems inhibiting irrelevant distractors contradicts a general response inhibition deficiency in ADHD, which may be explained by the relatively independency of working memory in this type of response inhibition. © 2007 Psychology Press

Exotic Quantum Order in Low-Dimensional Systems

Strongly correlated quantum systems in low dimensions often exhibit novel quantum ordering. This ordering is sometimes hidden and can be revealed only by examining new `dual' types of correlations. Such ordering leads to novel collective modes and fractional quantum numbers. Examples will be presented from quantum spin chains and the quantum Hall effect.Comment: To appear in Solid State Communications, Proceedings of Symposium on the Advancing Frontiers in Condensed Matter Science. 12pages +6 PS figure

Sex differences in tactile defensiveness in children with ADHD and their siblings

Contains fulltext : 71056.pdf (publisher's version ) (Closed access)Tactile defensiveness (TD) is a disturbance in sensory processing and is observed in some children with attention-deficit-hyperactivity disorder (ADHD). TD has been examined in male children with ADHD and in children with ADHD without differentiating by sex. As males and females with ADHD may differ in the clinical expression of the disorder and associated deficits, the aim of this study was to examine sex differences in TD in males and females with ADHD. Non-affected siblings were also examined to investigate familiality of TD. The Touch Inventory for Elementary-School-Aged Children was administered to 47 children with ADHD (35 males, 12 females; mean age 9y 8mo [SD 1y 11mo]), 36 non-affected siblings (21 males, 15 females; mean age 8y 10mo [SD 2y 4mo]), and 35 control children (16 males, 19 females; mean age 9y 5mo [SD 6mo]). Results indicated that females with ADHD displayed higher levels of TD than males with ADHD (who did not differ from control males). This suggests that TD is sex specific and may contribute to the identification of ADHD in females, thus improving diagnostic and therapeutic strength in this under-referred group. Non-affected siblings were unimpaired, regardless of sex, which suggests that TD is specific to the disorder and not part of a familial risk for ADHD

Reconstructed Rough Growing Interfaces; Ridgeline Trapping of Domain Walls

We investigate whether surface reconstruction order exists in stationary growing states, at all length scales or only below a crossover length, $l_{\rm rec}$. The later would be similar to surface roughness in growing crystal surfaces; below the equilibrium roughening temperature they evolve in a layer-by-layer mode within a crossover length scale $l_{\rm R}$, but are always rough at large length scales. We investigate this issue in the context of KPZ type dynamics and a checker board type reconstruction, using the restricted solid-on-solid model with negative mono-atomic step energies. This is a topology where surface reconstruction order is compatible with surface roughness and where a so-called reconstructed rough phase exists in equilibrium. We find that during growth, reconstruction order is absent in the thermodynamic limit, but exists below a crossover length $l_{\rm rec}>l_{\rm R}$, and that this local order fluctuates critically. Domain walls become trapped at the ridge lines of the rough surface, and thus the reconstruction order fluctuations are slaved to the KPZ dynamics

Comorbid problems in ADHD: degree of association, shared endophenotypes, and formation of distinct subtypes: Implications for a future DSM

We aimed to assess which comorbid problems (oppositional defiant behaviors, anxiety, autistic traits, motor coordination problems, and reading problems) were most associated with Attention-Deficit/Hyperactivity Disorder (ADHD); to determine whether these comorbid problems shared executive and motor problems on an endophenotype level with ADHD; and to determine whether executive functioning (EF)-and motor-endophenotypes supported the hypothesis that ADHD with comorbid problems is a qualitatively different phenotype than ADHD without comorbid problems. An EF-and a motor-endophenotype were formed based on nine neuropsychological tasks administered to 816 children from ADHD-and control-families. Additional data on comorbid problems were gathered using questionnaires. Results indicated that oppositional defiant behaviors appeared the most important comorbid problems of ADHD, followed by autistic traits, and than followed by motor coordination problems, anxiety, and reading problems. Both the EF-and motor-endophenotype were correlated and cross-correlated in siblings to autistic traits, motor coordination problems and reading problems, suggesting ADHD and these comorbid problems may possibly share familial/genetic EF and motor deficits. No such results were found for oppositional defiant behaviors and anxiety. ADHD in co-occurrence with comorbid problems may not be best seen as a distinct subtype of ADHD, but further research is warranted