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pubmed: attention deficit hy...
NCBI: db=pubmed; Term=attention deficit hyperactivity
Methylphenidate Effects on Neural Activity During Response Inhibition in Healthy Humans.
Methylphenidate Effects on Neural Activity During Response Inhibition in Healthy Humans.
Cereb Cortex. 2012 May 10;
Authors: Costa A, Riedel M, Pogarell O, Menzel-Zelnitschek F, Schwarz M, Reiser M, Möller HJ, Rubia K, Meindl T, Ettinger U
Abstract
Methylphenidate (MPH) is a catecholamine transporter blocker, with dopamine agonistic effects in the basal ganglia. Response inhibition, error detection, and its mediating frontostriatal brain activation are improved by MPH in patients with attention-deficit/hyperactivity disorder. However, little is known about the effects of MPH on response inhibition and error processing or its underlying brain function in healthy individuals. Therefore, this study employed functional magnetic resonance imaging (fMRI) and 2 response inhibition tasks in 52 healthy males. Subjects underwent fMRI during a go/no-go task and a tracking stop-signal task after administration of 40 mg MPH and placebo in a double-blind, placebo-controlled, repeated-measures design. Results revealed task- and condition-specific neural effects of MPH: it increased activation in the putamen only during inhibition errors but not during successful inhibition and only in the go/no-go task. We speculate that task specificity of the effect might be due to differences in the degree of error saliency in the 2 task designs, whereas errors were few in the go/no-go task and thus had high saliency and the stop-signal task was designed to elicit 50% of errors in all subjects, diminishing the error saliency effect. The findings suggest that neural MPH effects interact with the saliency of the behavior under investigation.
PMID: 22581848 [PubMed - as supplied by publisher]
A Cross-Lagged Model of the Development of ADHD Inattention Symptoms and Rapid Naming Speed.
A Cross-Lagged Model of the Development of ADHD Inattention Symptoms and Rapid Naming Speed.
J Abnorm Child Psychol. 2012 May 13;
Authors: Arnett AB, Pennington BF, Willcutt E, Dmitrieva J, Byrne B, Samuelsson S, Olson RK
Abstract
Although previous research has identified contemporaneous associations between cognitive deficits and symptom phenotypes in Attention Deficit/Hyperactivity Disorder, no studies have as yet attempted to identify direction of effect. The present study used cross-lagged path modeling to examine competing hypotheses about longitudinal associations between rapid naming speed and symptoms of inattention in children. 1,506 school-age twins from Australia and the U.S. were tested for inattention, hyperactivity/impulsivity, and rapid naming speed at three and four time points, respectively. Symptom severity of inattention from Kindergarten to fourth grade is consistently predicted by previous rapid naming, over and above auto-regressive and correlational associations in the model. Likewise, inattention symptoms have a small but significant predictive effect on subsequent rapid naming. The findings support a reciprocal relationship between naming speed and ADHD inattentive symptoms.
PMID: 22581405 [PubMed - as supplied by publisher]
Parent-Reported Attention Deficit/Hyperactivity Symptomatology in Preschool-Aged Children: Factor Structure, Developmental Change, and Early Risk Factors.
J Abnorm Child Psychol. 2012 May 12;
Authors: Willoughby MT, Pek J, Greenberg MT,
Abstract
Although Attention Deficit/Hyperactivity Disorder (ADHD) has increasingly been studied in preschool-aged children, relatively few studies have provided a comprehensive evaluation of the factor structure and patterns of developmental changes in parent-reported ADHD symptomatology across the early childhood period. This study used confirmatory factor analyses to test for longitudinal measurement invariance of ADHD symptoms and semi-parametric finite mixture models to identify prototypic patterns of developmental changes in ADHD symptomatology from 3 to 5 years of age. Participants were 1155 children and their parents who participated in a prospective longitudinal study involving a representative sample of children who resided in six non-metropolitan counties in the United States. Results indicated that (1) ADHD symptomatology was best represented by a single latent factor that exhibited partial measurement invariance from 3 to 5 years of age, (2) 8.5 % of children exhibited sustained high levels of ADHD symptoms from age 3-5 years, and (3) a variety of risk factors differentiated children with sustained high from those with sustained low levels of ADHD, relatively few (most notably caregiver education) were able to differentiate children with sustained high levels of ADHD symptoms from all other groups. Children who exhibit persistent ADHD symptomatology across the early childhood period may define a clinically important group for etiologic research and/or early intervention efforts.
PMID: 22581375 [PubMed - as supplied by publisher]
Dissecting the clinical phenotype associated with mosaic type-2 NF1 microdeletions.
Dissecting the clinical phenotype associated with mosaic type-2 NF1 microdeletions.
Neurogenetics. 2012 May 13;
Authors: Kehrer-Sawatzki H, Vogt J, Mußotter T, Kluwe L, Cooper DN, Mautner VF
Abstract
Patients with large deletions of the NF1 gene and its flanking regions (termed NF1 microdeletions) generally exhibit more severe clinical manifestations of neurofibromatosis type-1 (NF1). Here, we have investigated the clinical phenotype displayed by eight patients harbouring mosaic type-2 NF1 microdeletions. These patients did not exhibit facial dysmorphism, attention deficit hyperactivity disorder, delayed cognitive development and/or learning disabilities, cognitive impairment, congenital heart disease, hyperflexibility of joints, large hands and feet, muscular hypotonia or bone cysts. All these features have previously been reported to be disproportionately associated with germline (i.e. non-mosaic) type-1 NF1 microdeletions as compared with the general NF1 population. Plexiform neurofibromas were also less prevalent in patients with mosaic type-2 NF1 microdeletions as compared with patients carrying constitutional (germline) type-1 NF1 microdeletions. Five of the eight patients with mosaic type-2 deletions investigated here had 20-250 cutaneous neurofibromas, but only one of them exhibited a high load of cutaneous neurofibromas (N?>?1,000). By contrast, a previous study indicated a high burden of cutaneous neurofibromas (N?>?1,000) in 50 % of adult patients with germline type-1 NF1 deletions. Patients with germline type-1 NF1 microdeletions have been reported to have an increased lifetime risk of 16-26 % for a malignant peripheral nerve sheath tumour (MPNST). In this study, one of the eight investigated mosaic type-2 microdeletion patients developed an MPNST. We conclude that patients with mosaic type-2 NF1 microdeletions may also be at an increased risk of MPNSTs despite their generally milder disease manifestations as compared with germline type-1 NF1 microdeletions.
PMID: 22581253 [PubMed - as supplied by publisher]
Region-specific elevation of D(1) receptor-mediated neurotransmission in the nucleus accumbens of SHR, a rat model of attention deficit/hyperactivity disorder.
Neuropharmacology. 2012 May 10;
Authors: Ohno Y, Okano M, Masui A, Imaki J, Egawa M, Yoshihara C, Tatara A, Mizuguchi Y, Sasa M, Shimizu S
Abstract
Spontaneously hypertensive rats (SHR) are widely used as a rat model of attention deficit/hyperactivity disorder (AD/HD). Here, we conducted neurochemical and behavioral studies in SHR to clarify the topographical alterations in neurotransmissions linked to their behavioral abnormalities. In the open-field test, juvenile SHR showed a significant hyperactivity in ambulation and rearing as compared with Wistar Kyoto rats (WKY). Brain mapping analysis of Fos-immunoreactivity (IR) revealed that SHR showed a marked increase in Fos expression in the core part (AcC) of the nucleus accumbens (NAc). Small to moderate increases were also observed in the shell part of the NAc and some regions of the cerebral cortex (e.g., parietal association cortex). These changes in Fos expression were region-specific and the Fos-IR levels in other brain regions (e.g., hippocampus, amygdala, striatum, thalamus and hypothalamus) were unaltered. In addition, treatment of SHR with the selective D(1) antagonist SCH-23390 significantly reversed both behavioral hyperactivity and elevated Fos expression in the AcC and cerebral cortex. The present study suggests that D(1) receptor-mediated neurotransmission in the AcC is region-specifically elevated in SHR, which could be responsible for behavioral hyperactivity.
PMID: 22580374 [PubMed - as supplied by publisher]
Isolation rearing as a preclinical model of attention/deficit-hyperactivity disorder.
Isolation rearing as a preclinical model of attention/deficit-hyperactivity disorder.
Behav Brain Res. 2012 May 2;
Authors: Yates JR, Darna M, Gipson CD, Dwoskin LP, Bardo MT
Abstract
Rats raised in an isolated condition (IC) are impulsive and hyperactive compared to rats raised in an enriched condition (EC), suggesting that isolation rearing may be a preclinical model of attention-deficit/hyperactivity disorder (ADHD). The current study determined if administration of methylphenidate (MPH), a dopamine transporter (DAT) blocker used in the treatment of ADHD, reduces the hyperactivity observed in IC rats toward levels observed in EC rats. Another goal was to determine if chronic MPH treatment differentially alters DAT function in EC and IC rats in medial prefrontal cortex (mPFC) or orbital frontal cortex (OFC). IC and EC rats were treated with either MPH (1.5mg/kg, p.o.) or vehicle from postnatal days (PND) 28-51. On PND 28 and 51, rats were evaluated for MPH-induced locomotor activity. On PND 55-63, in vitro [(3)H]DA uptake assays were performed in mPFC and OFC. At both PND 28 and 51, IC rats were hyperactive compared to EC rats. At PND 28, MPH increased activity in EC rats only. At PND 51, MPH did not alter locomotor activity in IC or EC rats. Beginning at PND 55, basal uptake of [(3)H]dopamine in IC rats was higher in mPFC and lower in OFC compared to EC rats. The basal differences in DAT function were normalized by MPH treatment in mPFC, but not in OFC. These findings suggest that isolation rearing may not represent a valid predictive model for screening effective medications in the treatment of hyperactivity associated with ADHD.
PMID: 22580232 [PubMed - as supplied by publisher]
Prevalence of attention-deficit/hyperactivity disorder in patients with pediatric allergic disorders: A nationwide, population-based study.
J Microbiol Immunol Infect. 2012 May 11;
Authors: Shyu CS, Lin HK, Lin CH, Fu LS
Abstract
BACKGROUND: Allergic disorders are common, chronic conditions in pediatric populations. The characteristic symptoms of allergic disorders mainly include bronchial asthma (BA), allergic rhinitis (AR), and atopic dermatitis (AD), all of which may disturb sleep, leading to daytime inattention, irritability, and hyperactivity, which are also components of attention-deficit/hyperactivity disorder (ADHD). Conflicting data exist in the literature regarding the relationship between ADHD and allergic disorders. The aim of this nationwide, population-based study is to examine the prevalence and risk of developing ADHD among allergic patients in a pediatric group. METHODS: Data from a total of 226,550 pediatric patients under 18 years of age were collected from Taiwan's National Health Insurance Research Database recorded from January 1 to December 31, 2005 and analyzed. We calculated the prevalence of allergic diseases based on various demographic variables, including ADHD. We also used multivariable logistic regression to analyze the risk factors of ADHD. RESULTS: In 2005, the period prevalence rates of allergic disorders and ADHD in persons under the age of 18 were 21.5% and 0.6%, respectively. Pediatric patients with allergic disorder(s) had a substantially increased rate of developing ADHD (p < 0.001) in terms of period prevalence and odds ratio (OR). This significance existed across various demographic groups regardless of age, gender, location, or degree of urbanization of their residence. BA and AR, but not AD, were determined to be risk factors for ADHD. Co-morbidities of allergic disorders, including AR+AD, AR+BA and AR+BA+AD, but not BA+AD, were also determined to increase the risk of ADHD. CONCLUSION: Allergic disorders appear to increase the risk of ADHD in pediatric patients. Our detailed analysis shows that the main contributing factor is AR. Co-morbidity with AD, BA, and BA+AD in AR patients further increases the risk of ADHD.
PMID: 22580087 [PubMed - as supplied by publisher]
Accommodative response and cortical activity during sustained attention.
Accommodative response and cortical activity during sustained attention.
Vision Res. 2012 May 2;
Authors: Poltavski DV, Biberdorf D, Petros TV
Abstract
Greater accommodative lag and vergence deficits have been linked to attentional deficits similar to those observed in Attention Deficit Hyperactivity Disorder (ADHD). The purpose of the present study was to assess the effect of accommodative-vergence stress on a measure of sustained attention (Conners CPT) used in the diagnosis of ADHD. Twenty-seven normal non-ADHD adults completed the Conners CPT twice: wearing -2.00 D lenses and normally (without the -2.00 D lenses) in a counterbalanced order with at least 24h between the sessions. Simultaneous recording of participants' dynamic accommodative responses was performed from the right eye using the Grand Seiko WAM-5500 auto-refractor and electroencephalographic activity (EEG) in the left prefrontal region using the Neurosky Mindset headset. The results demonstrated a significantly greater accommodative lag in the -2.00 D stress condition and a significantly poorer performance on the Conners CPT as indexed by slower reaction time, greater standard error of hit reaction time, grater response variability, poorer stimulus detectability and a greater number of perseverations. No differences were observed on measures of EEG in the theta (4-7Hz), alpha (8-12Hz), and beta (12-20Hz) bands. Moreover, when directly juxtaposed with each EEG band in multiple linear regression analyses, greater accommodative lag in the stress condition was significantly associated with a greater probability of clinical classification on the Conners CPT, and was also marginally predictive of the number of omissions recorded in the stress condition. The results demonstrated that sustained attention can be influenced by such factors as accommodative-vergence stress and suggest that bottom-up processes can contribute to and potentially exacerbate attentional problems in individuals with ADHD. The study also showed that cortical dysfunction (while sufficient) may not be a necessary condition for attentional deficits.
PMID: 22580016 [PubMed - as supplied by publisher]
Developmental sub-chronic exposure to chlorpyrifos reduces anxiety-related behavior in zebrafish larvae.
Neurotoxicol Teratol. 2012 May 8;
Authors: Richendrfer H, Pelkowski SD, Colwill RM, Créton R
Abstract
Neurobehavioral disorders such as anxiety, autism, and attention deficit hyperactivity disorders are typically influenced by genetic and environmental factors. Although several genetic risk factors have been identified in recent years, little is known about environmental factors that either cause neurobehavioral disorders or contribute to their progression in genetically predisposed individuals. One environmental factor that has raised concerns is chlorpyrifos, an organophosphate pesticide that is widely used in agriculture and is found ubiquitously in the environment. In the present study, we examined the effects of sub-chronic chlorpyrifos exposure on anxiety-related behavior during development using zebrafish larvae. We found that sub-chronic exposure to 0.01 or 0.1?M chlorpyrifos during development induces specific behavioral defects in 7-day-old zebrafish larvae. The larvae displayed decreases in swim speed and thigmotaxis, yet no changes in avoidance behavior were seen. Exposure to 0.001?M chlorpyrifos did not only affect swimming, thigmotaxis, or avoidance behavior and exposure to 1?M chlorpyrifos induced behavioral defects, but also induced defects in larval morphology. Since thigmotaxis, a preference for the edge, is an anxiety-related behavior in zebrafish larvae, we propose that sub-chronic chlorpyrifos exposure interferes with the development of anxiety-related behaviors. The results of this study provide a good starting point for examination of the molecular, cellular, developmental, and neural mechanisms that are affected by environmentally relevant concentrations of organophosphate pesticides. A more detailed understanding of these mechanisms is important for the development of predictive models and refined health policies to prevent toxicant-induced neurobehavioral disorders.
PMID: 22579535 [PubMed - as supplied by publisher]
Treating ADHD: addressing the needs of college students.
Treating ADHD: addressing the needs of college students.
J Clin Psychiatry. 2012 Apr;73(4):e13
Authors: Culpepper L, King P
Abstract
College students with undiagnosed attention-deficit/hyperactivity disorder (ADHD) exhibit varying symptoms and may have trouble in class, be involved in driving accidents, be late to appointments, be disruptive, and abuse alcohol. Clinicians and others in a position to recognize and identify behaviors indicative of ADHD should either complete a thorough assessment for ADHD, including disorders that commonly co-occur with or are mistaken for the illness, or refer students to someone who can. For students with a comprehensive evaluation who are diagnosed with ADHD, special accommodations are available on campus. Clinicians can provide students with several strategies to manage their disorder and improve their chances of having a successful academic career.
PMID: 22579156 [PubMed - in process]
