Attention deficit hyperactivity disorder: focus on genetics

BACKGROUND: Leuconostoc spp. are gram-positive coccobacilli, catalase and oxidase negative, vancomycin resistant, with a not clearly defined role in human infectious. Cases of infection have been reported previously but it has not been described confirmed infective endocarditis due to Leuconostoc mesenteroides. METHODS: We describe a case of prosthetic valve endocarditis in a 72-years-old woman with a long previous history of cardiac disease but without other immunological disorders. She developed a heart failure because of prosthetic aortic valve dysfunction. CONCLUSIONS: Leuconostoc mesenteroides should be considered as a potential cause of infective endocarditis and listed in the group of vancomycin-resistant microorganism.     

Attention deficit hyperactivity disorder: Clinical presentation and correlates in a South African sample.

The clinical presentation of attention deficit hyperactivity disorder (ADHD), its relationship to other developmental delays, and its association with socioeconomic variables were explored in a multicultural, South African clinical sample. Results indicate that, for this sample, ADHD is manifested by hyperactivity, attention deficits, disciplinary problems, social impairment, aggression, and impulsiveness and that these components cohere in the manner of a unidimensional syndrome. ADHD was found to be most frequently associated with behavior disorders followed by learning disabilities and speech delays. No relationship with socioeconomic variables was found. The findings have implications for the reconstruction of mental health structures in South Africa. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comprehensive evaluation of attention deficit disorder with and without hyperactivity as defined by research criteria.

Children with attention deficit disorder with hyperactivity (ADD+H; N?=?48) were compared with those without hyperactivity (ADD-H; N?=?42), as well as with learning disabled and control children, on an extensive battery of interviews, behavior ratings, tests, and direct observations. ADD+H children had more externalizing and internalizing symptoms by parent and teacher report; were more off task during vigilance testing; and had more substance abuse, ADD+H, and aggression among their relatives than did the other groups. ADD-H children were more daydreamy and lethargic by teacher report, more impaired in perceptual–motor speed, and had more anxiety disorders among their relatives than did ADD+H children. Results indicate that these 2 types of ADD may be separate, distinct childhood disorders than subtypes of a common attention deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention deficit hyperactivity disorder: advances in cognitive, neurobiological, and genetic research

Conceptual and technological advances in cognitive neuroscience and molecular genetics have the potential to identify the pathogenesis of psychiatric disorders. This article reviews the application of these technologies to the scientific study of attention deficit hyperactivity disorder. It begins with a summary of shifts in conceptualization and scientific study of this common condition. This is followed by a critical review of findings from recent cognitive, neuroimaging, and genetic studies. The available data do not yet permit an integration across these different levels of enquiry, but implicate problems in response inhibition, dysfunction of frontostriatal networks, and genetic factors in the pathogenesis of this complex behavioral phenotype. The review closes with suggestions for future interdisciplinary research.     

Divided attention in youth-onset psychosis and attention deficit/hyperactivity disorder.

The authors used pupillary dilations to test whether divided attention deficits in youth-onset psychosis and attention deficit/hyperactivity disorder (ADHD) were because of limitations in recruitment of cognitive resources or abnormalities in attention allocation. Eight- to 19-year-olds with youth-onset psychosis or ADHD were administered a divided attention test consisting of an auditory digit span (DS) task and a simple visual response time (RT) task. In 4 conditions, participants performed neither (no task), 1 (DS or RT only), or both tasks (dual). Dependent variables were DS accuracy, RT, and pupillary dilation to digits as an estimate of recruitment of cognitive resources. The authors found no evidence for an abnormal attention strategy in either disorder. Instead, results were consistent with the hypothesis that both clinical groups have limitations in resource recruitment. These limitations were more severe in psychosis than in ADHD. Findings indicate that both clinical groups had difficulties in regulating physiological arousal on a moment-to-moment basis in accordance with task demands. Findings also demonstrate the importance of taking into account difficulties that constrain performance on simple tasks before interpreting impairments on complex tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention deficit hyperactivity disorder and anxiety: is there an association with neurodevelopmental deficits?

OBJECTIVE: The co-occurrence of attention deficit hyperactivity disorder (ADHD) and anxiety is a well-established clinical observation. However, its status as a clinical construct is debated. We review the prevalence of 'ADHD and anxiety', its definitions, and its clinical correlates and we hypothesise that neurodevelopmental deficits may be increased in 'ADHD and anxiety'. METHOD: The authors identified empirical studies in the psychiatric and psychological literature. The search categories included hyperactivity, attention deficit hyperactivity disorder, attention deficit disorder and anxiety. RESULTS: 'ADHD and anxiety' is considerably more common in clinical than epidemiological samples. There are a range of definitions which address the situational variation in both ADHD and anxiety symptoms and the use of categorical and continuous variables to define them. Yet the nature of the anxiety is still unclear. It is associated with a poor response to psychostimulant medication treatment, and alternative pharmacotherapy approaches have been suggested. There is a controversy about whether neurodevelopmental deficits are associated with hyperactivity alone, or anxiety, or both. CONCLUSIONS: 'ADHD and anxiety' is important clinically because it is common and less responsive to psychostimulant medication. Important research issues include its heterogeneity which necessitates the collection of parent, teacher, and child self-reports of symptoms' presence or absence and the hypothesis that neurodevelopmental deficits may be increased in this group of children.     

Attention deficit hyperactivity disorder (ADHD) is associated with early onset substance use disorders

We evaluated the association between attention deficit hyperactivity disorder (ADHD) and the age of onset of psychoactive substance use disorders (PSUD) in adults with ADHD. We hypothesized that ADHD and psychiatric comorbidity would be risk factors for early onset PSUD. We compared 120 referred adults having a clinical diagnosis of childhood-onset ADHD with 268 non-ADHD adults. All diagnoses were obtained using DSM-III-R based structured psychiatric interviews. We used group comparisons of age at onset and Cox proportional hazard models to examine the development of PSUD over time. ADHD was associated with earlier onset of PSUD independently of psychiatric comorbidity. Conduct and juvenile bipolar disorders conferred a significantly increased risk for early onset PSUD independently of ADHD. Psychiatric disorders commonly emerged before the onset of PSUD in both groups. Persistent ADHD with and without psychiatric comorbidity was associated with adolescent onset PSUD. In addition, comorbidity with conduct and juvenile bipolar disorders predicted very early onset PSUD in both ADHD and non-ADHD individuals. These findings confirm and extend previous findings documenting important associations between PSUD and psychiatric comorbidity including persistent ADHD.     

Diversity and attention deficit hyperactivity disorder

Smooth muscle contraction is regulated primarily by the reversible phosphorylation of myosin triggered by an increase in sarcoplasmic free Ca2+ concentration ([Ca2+]i). Contraction can, however, be modulated by other signal transduction pathways, one of which involves the thin filament-associated protein calponin. The h1 (basic) isoform of calponin binds to actin with high affinity and is expressed specifically in smooth muscle at a molar ratio to actin of 1:7. Calponin inhibits (i) the actin-activated MgATPase activity of smooth muscle myosin (the cross-bridge cycling rate) via its interaction with actin, (ii) the movement of actin filaments over immobilized myosin in the in vitro motility assay, and (iii) force development or shortening velocity in permeabilized smooth muscle strips and single cells. These inhibitory effects of calponin can be alleviated by protein kinase C (PKC)-catalysed phosphorylation and restored following dephosphorylation by a type 2A phosphatase. Three physiological roles of calponin can be considered based on its in vitro functional properties: (i) maintenance of relaxation at resting [Ca2+]i, (ii) energy conservation during prolonged contractions, and (iii) Ca(2+)-independent contraction mediated by phosphorylation of calponin by PKC epsilon, a Ca(2+)-independent isoenzyme of PKC.     

Advancing the spontaneous hypertensive rat model of attention deficit/hyperactivity disorder.

To advance the spontaneous hypertensive rat (SHR) model of attention deficit/hyperactivity disorder (ADHD), experiments examined the SHR in tasks recognized to assess functioning of the prefrontal cortex or dorsal striatal. Tasks included odor-delayed win-shift (nonspatial working and reference memory), win-stay (habit learning), and attentional set-shifting (attention and behavioral flexibility). In Experiment 1, the SHR strain was compared with Wistar-Kyoto (WKY) and Wistar-Kyoto Hypertensive (WKHT) strains on the first 2 tasks. In Experiment 2, oral methylphenidate (1.5 mg/kg) and vehicle (water) were evaluated on all 3 tasks in SHR and WKY strains. Results demonstrated that the SHR made significantly more errors in the odor-delayed win-shift, win-stay, and attentional set-shifting tasks compared with the WKY. Similar performances in the WKY and WKHT indicated that deficits observed in the SHR were not related solely to hypertension. Treating the SHR with methylphenidate eliminated strain differences in all 3 tasks. These findings provide evidence that the SHR is a valid model for studying ADHD-associated neurocognitive deficits. Moreover, the current behavioral approach is appropriate to assess novel medications developed to target ADHD-associated neurocognitive deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of chronic nicotine and methylphenidate in adults with attention deficit/hyperactivity disorder.

Acute nicotine treatment has been found to reduce symptoms of attention deficit/hyperactivity disorder in adults (E. D. Levin, C. K. Conners, et al., 1996). In this study, chronic nicotine effects were compared with placebo and methylphenidate. Acute and chronic nicotine treatment significantly attenuated the rise in hit reaction time standard error over session blocks on the Conners Continuous Performance Test (C. K. Conners et al., 1996). Acute nicotine significantly reduced severity of clinical symptoms on the Clinical Global Impressions scale (National Institute of Mental Health, 1985). Nicotine caused a significant decrease in self-report of depressive mood as measured by the Profile of Mood States test (D. M. McNair, M. Lorr, & L. F. Droppleman, 1981). This small study (40 participants) provided evidence that nicotine treatment can reduce severity of attentional deficit symptoms and produce improvement on an objective computerized attention task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropsychological functioning in nonreferred siblings of children with attention deficit/hyperactivity disorder.

The goal of this study was to assess neuropsychological functioning in nonreferred siblings of children with attention deficit/hyperactivity disorder (ADHD). Participants were 156 siblings of ADHD probands with (N?=?40) and without (N?=?116) ADHD (according to criteria of the Diagnostic and Statistical Manual of Mental Disorders [3rd edition, revised; American Psychiatric Association, 1987]) and 118 siblings of non-ADHD normal controls of similar age, IQ, and grade level. Information on attention, executive, and memory functions was obtained in a standardized manner without knowledge of clinical status. Compared with siblings of controls, siblings with ADHD were significantly impaired on the Stroop test and on verbal learning and memory. In contrast, siblings without ADHD were similar to controls on virtually all measures. These data suggest that some executive, attention, and verbal learning deficits are found in nonreferred individuals with ADHD but that neuropsychological deficits are unlikely to constitute an endophenotype to ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comprehension of televised stories in boys with attention deficit/hyperactivity disorder and nonreferred boys.

Two studies compared comprehension of televised stories by 7- to 12-year-old boys with attention deficit/hyperactivity disorder (ADHD) and nonreferred comparison boys. Boys watched one show with toys present and one with toys absent. Visual attention was continuously recorded, and recall was tested after each show. Across studies, visual attention was high with toys absent but decreased sharply with toys present for boys with ADHD. Groups showed similar levels of cued recall of discrete units of information regardless of differences in attention. When recall tasks and television story structure required knowledge of relations among events, the reduced attention of boys with ADHD interfered with recall. Although visual attention of comparison boys also decreased to some extent with toys present, there was no such decrement in recall. Implications of the difficulties children with ADHD have in integrated story comprehension are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of methylphenidate on discounting of delayed rewards in attention deficit/hyperactivity disorder.

Impulsivity is a central component of attention deficit/hyperactivity disorder (ADHD). Delay discounting, or a preference for smaller, immediate rewards over larger, delayed rewards, is considered an important aspect of impulsivity, and delay-related impulsivity has been emphasized in etiological models of ADHD. In this study, we examined whether stimulant medication, an effective treatment for ADHD, reduced discounting of delayed experiential and hypothetical rewards among 49 children (ages 9–12 years) with ADHD. After a practice day, participants completed a 3-day double-blind placebo-controlled acute medication assessment. Active doses were long-acting methylphenidate (Concerta), with the nearest equivalents of 0.3 and 0.6 mg/kg TID immediate-release methylphenidate. On each testing day, participants completed experiential (real-world money in real time) and hypothetical discounting tasks. Relative to placebo, methylphenidate reduced discounting of delayed experiential rewards but not hypothetical rewards. Broadly consistent with etiological models that emphasize delay-related impulsivity among children with ADHD, these findings provide initial evidence that stimulant medication reduces delay discounting among those with the disorder. The results also draw attention to task parameters that may influence the sensitivity of various delay discounting measures to medication effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment and diagnosis of attention deficit/hyperactivity disorder in pediatric general practice

Thorough assessment is a critical first step in the treatment of any psychiatric disorder. The need for rigorous assessment procedures is underscored for those disorders, such as Attention Deficit/Hyperactivity Disorder (ADHD) of childhood, that have a high comorbidity with other common psychiatric disorders, including childhood depression and anxiety. Extensive research regarding diagnostic procedures for ADHD has demonstrated the importance of obtaining assessment data from multiple informants and in multiple modalities as a way of confirming ADHD diagnoses. This article describes how a physician in general pediatric practice might execute a thorough initial and follow-up assessment of a child's ADHD symptomology.     

Injury risk factors in children with attention deficit hyperactivity disorder.

Processes related to injury in children with Attention Deficit Hyperactivity Disorder (ADHD) were examined. Two groups of 7–11-year-old boys (14 ADHD and 16 controls) watched a videotape simulating play activities in order for them to identify risky behaviors and then answered questions about risky scenes. Groups did not differ in ability to identify hazards, but children with ADHD anticipated less severe consequences following risky behavior and reported fewer active methods of preventing injury than did controls. Cognitive factors, including lower expectations of personal risk in hazardous situations and less ability to generate prevention strategies and safety rules, may contribute to increased injury liability in boys with ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Executive function in children with Tourette syndrome and/or attention deficit hyperactivity disorder

Tourette Syndrome (TS) in children is associated with various neurobehavioral disorders including attention deficit hyperactivity disorder (ADHD). Children with TS and ADHD show some difficulties with neuropsychological tasks, but we do not know if children with TS alone have neuropsychological deficits. To assess specific cognitive differences among children with TS and/or ADHD, we administered a battery of neuropsychological tests, including 10 tasks related to executive function (EF), to 10 children with TS-only, 48 with ADHD-only, and 32 with TS + ADHD. Children in all groups could not efficiently produce output on a timed continuous performance task [Test of Variables of Attention (TOVA) mean reaction time and reaction time variability]. Children with TS-only appeared to have fewer EF impairments and significantly higher perceptual organization scores than children with TS + ADHD or ADHD-only. These findings suggest that deficiencies in choice reaction time and consistency of timed responses are common to all three groups, but children with TS-only have relatively less EF impairment than children with TS + ADHD or ADHD-only.