Spatial contrast sensitivity in adolescents with autism spectrum disorders

Adolescents with autism spectrum disorders (ASD) and typically developing (TD) controls underwent a rigorous psychophysical assessment that measured contrast sensitivity to seven spatial frequencies (0.5-20 cycles/degree). A contrast sensitivity function (CSF) was then fitted for each participant, from which four measures were obtained: visual acuity, peak spatial frequency, peak contrast sensitivity, and contrast sensitivity at a low spatial frequency. There were no group differences on any of the four CSF measures, indicating no differential spatial frequency processing in ASD. Although it has been suggested that detail-oriented visual perception in individuals with ASD may be a result of differential sensitivities to low versus high spatial frequencies, the current study finds no evidence to support this hypothesis

Time courses of improvement and symptom remission in children treated with atomoxetine for attention-deficit/hyperactivity disorder: analysis of Canadian open-label studies

<p>Abstract</p> <p>Background</p> <p>The relatively short durations of the initial pivotal randomized placebo-controlled trials involving atomoxetine HCl for the treatment of attention-deficit/hyperactivity disorder (ADHD) provided limited insight into the time courses of ADHD core symptom responses to this nonstimulant, selective norepinephrine reuptake inhibitor. The aim of this analysis was to evaluate time courses of treatment responses or remission, as assessed by attainment of prespecified scores on the ADHD Rating Scale-IV-Parent Version: Investigator Administered and Scored (ADHDRS-IV-PI) and the Clinical Global Impressions-ADHD-Severity (CGI-ADHD-S) scales, during up to 1 year of atomoxetine treatment in children with ADHD.</p> <p>Methods</p> <p>Using pooled data from three Canadian open-label studies involving 338 children ages 6-11 years with ADHD who were treated with atomoxetine for 3, 6 and 12 months, and survival analysis methods for interval-censored data, we estimated the time to: 1) improvement and robust improvement defined by ≥25% and ≥40% reductions from baseline ADHDRS-IV-PI total scores, respectively; and 2) remission using two definitions: a final score of ADHDRS-IV-PI ≤18 or a final score of CGI-ADHD-S ≤2.</p> <p>Results</p> <p>The median time to improvement was 3.7 weeks (~1 month), but remission of symptoms did not occur until a median of 14.3 weeks (~3.5 months) using the most stringent CGI-ADHD-S threshold. Probabilities of robust improvement were 47% at or before 4 weeks of treatment; 76% at 12 weeks; 85% at 26 weeks; and 96% at 52 weeks. Probabilities of remission at these corresponding time points were 30%, 59%, 77%, and 85% (using the ADHDRS-IV scale) and 8%, 47%, 67%, and 75% (using the CGI-ADHD-S scale). The change from atomoxetine treatment month 5 to month 12 of -1.01 (1.03) was not statistically significant (<it>p </it>= .33).</p> <p>Conclusions</p> <p>Reductions in core ADHD symptoms during atomoxetine treatment are gradual. Although approximately one-half of study participants showed improvement at 1 month of atomoxetine treatment, remission criteria were not met until about 3 months. Understanding the time course of children's responses to atomoxetine treatment may inform clinical decision making and also influence the durations of trials comparing the effects of this medication with other ADHD treatments.</p> <p>Trial Registrations</p> <p>clinicaltrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00191633">NCT00191633</a>, <a href="http://www.clinicaltrials.gov/ct2/show/NCT00216918">NCT00216918</a>, <a href="http://www.clinicaltrials.gov/ct2/show/NCT00191880">NCT00191880</a>.</p

Autism as a disorder of neural information processing: directions for research and targets for therapy

The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself

Shorter spontaneous fixation durations in infants with later emerging autism

Little is known about how spontaneous attentional deployment differs on a millisecond-level scale in the early development of autism spectrum disorders (ASD). We measured fine-grained eye movement patterns in 6-to 9-month-old infants at high or low familial risk (HR/LR) of ASD while they viewed static images. We observed shorter fixation durations (i.e. the time interval between saccades) in HR than LR infants. Preliminary analyses indicate that these results were replicated in a second cohort of infants. Fixation durations were shortest in those infants who went on to receive an ASD diagnosis at 36 months. While these findings demonstrate early-developing atypicality in fine-grained measures of attentional deployment early in the etiology of ASD, the specificity of these effects to ASD remains to be determined

Treating attention-deficit/hyperactivity disorder beyond symptom control alone in children and adolescents: a review of the potential benefits of long-acting stimulants

Attention-deficit/hyperactivity disorder (ADHD), one of the most common neuropsychiatric conditions of childhood, often has a chronic course and persists into adulthood in many individuals. ADHD may have a clinically important impact on health-related quality of life in children, a significant impact on parents’ emotional health and interfere with family activities/cohesion. To date, the main targets of ADHD treatment have focused on reducing the severity of symptoms during the school day and improving academic performance. However, the treatment of ADHD should reach beyond symptom control to address the issues of social competencies and improvement of health-related quality of life from the perspectives of individuals with ADHD and their families, to support them in reaching their full developmental potential. Methylphenidate (MPH) is recognised as the first-line choice of pharmacotherapy for ADHD in children and adolescents. This paper focuses on the importance and benefits to child development of ADHD symptom control beyond the school day only, i.e. extending into late afternoon and evening and uses the example of an extended-release MPH formulation (OROS® MPH) to demonstrate the potential benefits of active full day coverage (12 h) with a single daily dose. Concerns of long-term stimulant treatment are also discussed

Medio-Frontal and Anterior Temporal abnormalities in children with attention deficit hyperactivity disorder (ADHD) during an acoustic antisaccade task as revealed by electro-cortical source reconstruction

<p>Abstract</p> <p>Background</p> <p>Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent disorders in children and adolescence. Impulsivity is one of three core symptoms and likely associated with inhibition difficulties. To date the neural correlate of the antisaccade task, a test of response inhibition, has not been studied in children with (or without) ADHD.</p> <p>Methods</p> <p>Antisaccade responses to visual and acoustic cues were examined in nine unmedicated boys with ADHD (mean age 122.44 ± 20.81 months) and 14 healthy control children (mean age 115.64 ± 22.87 months, three girls) while an electroencephalogram (EEG) was recorded. Brain activity before saccade onset was reconstructed using a 23-source-montage.</p> <p>Results</p> <p>When cues were acoustic, children with ADHD had a higher source activity than control children in Medio-Frontal Cortex (MFC) between -230 and -120 ms and in the left-hemispheric Temporal Anterior Cortex (TAC) between -112 and 0 ms before saccade onset, despite both groups performing similarly behaviourally (antisaccades errors and saccade latency). When visual cues were used EEG-activity preceding antisaccades did not differ between groups.</p> <p>Conclusion</p> <p>Children with ADHD exhibit altered functioning of the TAC and MFC during an antisaccade task elicited by acoustic cues. Children with ADHD need more source activation to reach the same behavioural level as control children.</p

Pattern Classification of Working Memory Networks Reveals Differential Effects of Methylphenidate, Atomoxetine, and Placebo in Healthy Volunteers

Stimulant and non-stimulant drugs can reduce symptoms of attention deficit/hyperactivity disorder (ADHD). The stimulant drug methylphenidate (MPH) and the non-stimulant drug atomoxetine (ATX) are both widely used for ADHD treatment, but their differential effects on human brain function remain unclear. We combined event-related fMRI with multivariate pattern recognition to characterize the effects of MPH and ATX in healthy volunteers performing a rewarded working memory (WM) task. The effects of MPH and ATX on WM were strongly dependent on their behavioral context. During non-rewarded trials, only MPH could be discriminated from placebo (PLC), with MPH producing a similar activation pattern to reward. During rewarded trials both drugs produced the opposite effect to reward, that is, attenuating WM networks and enhancing task-related deactivations (TRDs) in regions consistent with the default mode network (DMN). The drugs could be directly discriminated during the delay component of rewarded trials: MPH produced greater activity in WM networks and ATX produced greater activity in the DMN. Our data provide evidence that: (1) MPH and ATX have prominent effects during rewarded WM in task-activated and -deactivated networks; (2) during the delay component of rewarded trials, MPH and ATX have opposing effects on activated and deactivated networks: MPH enhances TRDs more than ATX, whereas ATX attenuates WM networks more than MPH; and (3) MPH mimics reward during encoding. Thus, interactions between drug effects and motivational state are crucial in defining the effects of MPH and ATX

Comparative genome analysis and genome-guided physiological analysis of Roseobacter litoralis

<p>Abstract</p> <p>Background</p> <p><it>Roseobacter litoralis </it>OCh149, the type species of the genus, and <it>Roseobacter denitrificans </it>OCh114 were the first described organisms of the <it>Roseobacter </it>clade, an ecologically important group of marine bacteria. Both species were isolated from seaweed and are able to perform aerobic anoxygenic photosynthesis.</p> <p>Results</p> <p>The genome of <it>R. litoralis </it>OCh149 contains one circular chromosome of 4,505,211 bp and three plasmids of 93,578 bp (pRLO149_94), 83,129 bp (pRLO149_83) and 63,532 bp (pRLO149_63). Of the 4537 genes predicted for <it>R. litoralis</it>, 1122 (24.7%) are not present in the genome of <it>R. denitrificans</it>. Many of the unique genes of <it>R. litoralis </it>are located in genomic islands and on plasmids. On pRLO149_83 several potential heavy metal resistance genes are encoded which are not present in the genome of <it>R. denitrificans</it>. The comparison of the heavy metal tolerance of the two organisms showed an increased zinc tolerance of <it>R. litoralis</it>. In contrast to <it>R. denitrificans</it>, the photosynthesis genes of <it>R. litoralis </it>are plasmid encoded. The activity of the photosynthetic apparatus was confirmed by respiration rate measurements, indicating a growth-phase dependent response to light. Comparative genomics with other members of the <it>Roseobacter </it>clade revealed several genomic regions that were only conserved in the two <it>Roseobacter </it>species. One of those regions encodes a variety of genes that might play a role in host association of the organisms. The catabolism of different carbon and nitrogen sources was predicted from the genome and combined with experimental data. In several cases, e.g. the degradation of some algal osmolytes and sugars, the genome-derived predictions of the metabolic pathways in <it>R. litoralis </it>differed from the phenotype.</p> <p>Conclusions</p> <p>The genomic differences between the two <it>Roseobacter </it>species are mainly due to lateral gene transfer and genomic rearrangements. Plasmid pRLO149_83 contains predominantly recently acquired genetic material whereas pRLO149_94 was probably translocated from the chromosome. Plasmid pRLO149_63 and one plasmid of <it>R. denitrifcans </it>(pTB2) seem to have a common ancestor and are important for cell envelope biosynthesis. Several new mechanisms of substrate degradation were indicated from the combination of experimental and genomic data. The photosynthetic activity of <it>R. litoralis </it>is probably regulated by nutrient availability.</p