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Background: The efficacy of three dietary treatments for ADHD has been repeatedly tested in randomized controlled trials (RCTs). These interventions are restricted elimination diets (RED), artificial food colour elimination (AFCE) and supplementation with free fatty acids (SFFA). There have been three systematic reviews and associated meta-analyses of the RCTs for each of these treatments. Scope: The aim of this review is to critically appraise the studies on the dietary treatments of ADHD, to compare the various meta-analyses of their efficacy that have been published and to identify where the design of such RCTs could be improved and where further investigations are needed. Findings: The meta-analyses differ in the inclusion and exclusion criteria applied to potentially eligible studies. The range of average effect sizes in standard deviation units is RED (0.29-1.2), AFCE (0.18-0.42) and SFFA (0.17-0.31). The methodology of many of the trials on which the meta-analyses are based is weak. Conclusions: Nevertheless, there is evidence from well-conducted studies for a small effect of SFFA. Restricted elimination diets may be beneficial, but large-scale studies are needed on unselected children, using blind assessment and including assessment of long-term outcome. Artificial food colour elimination is a potentially valuable treatment but its effect size remains uncertain, as does the type of child for whom it is likely to be efficacious. There are additional dietary supplements that have been used with children with ADHD. A systematic search identified 11 RCTs that investigated the effects of these food supplements. Despite positive results for some individual trials, more studies are required before conclusions can be reached on the value in reducing ADHD symptoms of any of these additional supplements.

Anxiety and depression are linked to lower academic performance. It is proposed that academic performance is reduced in young people with high levels of anxiety or depression as a function of increased test-specific worry that impinges on working memory central executive processes. Participants were typically developing children (12 to 13-years-old) from two UK schools. The study investigated the relationship between negative affect, worry, working memory, and academic performance using self-report questionnaires, school administered academic test data, and a battery of computerized working memory tasks. Higher levels of anxiety and depression were associated with lower academic performance. There was support for a mediation hypothesis, where worry and central executive processes mediated the link between negative affect and academic performance. Further studies should test these hypotheses in larger longitudinal samples. Implications for school psychology practice and interventions in schools are discussed. (Contains 2 tables and 3 figures.)

Aim: To determine if the benefit of early confirmation of permanent childhood hearing impairment (PCHI) on children's receptive language development is associated with fewer behavioural problems. Method: Follow-up of a total population cohort of 120 children with PCHI of moderate or greater severity (greater than or equal to 40 decibels relative to hearing threshold level) (67 males, 53 females; mean age 7y 11mo, range 5y 5mo-11y 8mo) and 63 hearing children (37 males, 26 females; mean age 8y 1mo, range 6y 4mo-9y 10mo). The main outcome measures were the Strengths and Difficulties Questionnaire (SDQ) completed by teachers and parents and the Vineland Adaptive Behaviour Scales (VABS) which are completed on the basis of a parental interview. Results: Children with PCHI had lower standard scores than hearing children on the Daily Living Skills (p = 0.001) and the Socialisation (p = 0.001) scales of the VABS. They had significantly higher Total Behaviour Problem scores on the parent-rated (p = 0.002) and teacher-rated SDQ (p = 0.03). Children for whom PCHI was confirmed by 9 months did not have significantly fewer problems on the behavioural measures than those confirmed after that age (p = 0.635 and p = 0.196). Interpretation: Early confirmation has a beneficial effect on receptive language development but no significant impact in reducing behavioural problems in children with PCHI.

Background: There are well-replicated findings that link poor development on a range of communication skills with increased behavioural problems. This paper examines this relationship in children with hearing loss. Method: One hundred and twenty children with hearing loss (67 boys, 53 girls) and 63 hearing children (37 boys, 26 girls) with a mean age of 8 years from eight districts in Southern England were assessed for receptive and expressive language skills. The relationships between these measures and an aggregate of parent- and teacher-reported behaviour problems in the children were investigated. Results: Children with hearing loss had higher levels of behaviour problems compared to hearing children. Once the language abilities of children with hearing loss are taken into account, the negative effects of hearing loss on behaviour disappear. Conclusions: Behaviour problems are found more commonly in children with hearing loss and the level of behaviour problems is highest amongst those children with hearing loss with the least developed language capabilities.

Children born very prematurely are at risk of low average IQ and behaviour difficulties throughout childhood and adolescence. Associations among preterm birth, IQ and behaviour have been reported; however, the nature of the relationship among these outcomes is not fully understood. Some studies have proposed that the consequences of preterm birth, such as low average IQ, mediate the association between preterm birth and later behaviour difficulties. The aim of this study was to investigate the relationship among preterm birth, IQ and childhood behaviour problems, by testing mediation and moderation models. We assessed a UK sample of 69 very preterm (less than 32 weeks gestational age) and 70 term born children aged between 6 and 12 years on an abbreviated IQ test. Parental behaviour ratings were obtained using the Strengths and Difficulties Questionnaire. Mediation and moderation models were tested using hierarchical regression analyses. The findings indicate that IQ mediates the relationship between birth status and emotional behaviour problems. Furthermore, the results indicate that birth status moderates the relationship between IQ and behavioural difficulties, i.e., that the relationship between low IQ and behaviour problems is most pronounced for the preterm children. The findings highlight the importance of considering indirect effects in the study of outcome after very preterm birth.

State and trait anxiety define different aspects of anxiety, and may represent environmentally and genetically mediated components of this phenotype. Furthermore their relationship, where trait anxiety is expressed through levels of state anxiety under threatening circumstances, may represent a process of interplay between a genetic vulnerability factor and an environmental stressor. To test these hypotheses, we explored genetic and environmental influences on measures of state and trait anxiety in a sample of 1058 twins (521 males and 537 females) aged 8-16. The results were consistent with these hypotheses. State anxiety is largely influenced by environmental factors in males and females whereas trait anxiety shows moderate genetic effects and substantial non-shared environment effects. Their association was accounted for by non-shared environmental effects, with modest genetic and shared environmental inputs. The implications of these results for vulnerability mechanisms involving stress reactivity on anxiety are discussed.

This study investigated the effect of individual differences in state anxiety on tasks tapping the central executive, phonological, and visuo-spatial components of working memory (WM). It was designed to test Eysenck and Calvo's processing efficiency theory (PET) which suggests that the phonological and executive components of WM may be important in understanding learning outcomes in anxiety. Typically-developing children aged 9-10 years were split into high and low state anxiety groups. They performed three WM tasks--forward and backward digit span (assumed to measure phonological and central executive components of WM respectively) and a spatial working memory task (measuring the visuo-spatial component of WM). Measurements of task accuracy were taken as an indicator of performance outcome or effectiveness. Time taken to complete tasks and a subjective rating of mental effort were taken as measurements of performance efficiency. No differences were found between high and low state anxiety groups in task accuracy for any measure. Children in the high state anxiety group, however, took longer to complete the backward digit span task and reported increased mental effort in the forward digit span task, indicating some effect of anxiety on measures of performance efficiency.

The genetic study of ADHD has made considerable progress. Further developments in the field will be reliant in part on identifying the most appropriate phenotypes for genetic analysis. The use of both categorical and dimensional measures of symptoms related to ADHD has been productive. The use of multiple reporters is a valuable feature of the characterization of psychopathology in children. It is argued that the use of aggregated measures to characterize the ADHD phenotype, particularly to establish its pervasiveness, is desirable. The recognition of the multiple comorbidities of ADHD can help to isolate more specific genetic influences. In relation to both reading disability and conduct disorder there is evidence that genes may be involved in the comorbid condition that are different from pure ADHD. To date, progress with the investigation of endophenotypes for ADHD has been disappointing. It is suggested that extending such studies beyond cognitive underpinnings to include physiological and metabolic markers might facilitate progress.

Background: Dissociation--a pattern of general disruption in memory and consciousness--has been found to be an important cognitive component of children's and adults' coping with severe trauma. Dissociative experiences include amnesia, identity disturbance, age regression, difficulty with concentration, and trance states. Stable individual differences in dissociative behaviors may represent a dissociative tendency trait that varies in the population independent of the influence of trauma. Method: In the current study, we examined genetic and environmental sources of variance in some of these behaviors by comparing 86 pairs of adoptive siblings and 102 pairs of full siblings from the Colorado Adoption Project (parents' and teachers' ratings), and 218 pairs of identical and 173 pairs of same-sex fraternal twins from the British Register for Child Twins (parents' ratings). The study used a dissociation scale comprised of six CBCL items. Results: Developmentally, there was no change in mean dissociation scores across middle childhood and adolescence, and individual differences were moderately stable. Both parents' and teachers' ratings showed moderate to substantial amounts of genetic and nonshared environmental variance and negligible shared environmental variance, and most of the parent-teacher agreement in their ratings was accounted for by overlapping genetic variance. Conclusions: The results support further research into possible genetic and environmental factors that contribute to dissociative tendencies in children and adolescents.

At 3 points in time over a 12-month period, this short-term longitudinal study examined 67 preschoolers' syllable, rime, and phoneme awareness; speech and language skills; and letter knowledge. Findings indicated that rime skills developed earlier than phoneme skills. Structural equation models showed that articulatory skills and syllable and rime awareness predicted later phoneme awareness. (Author/KB)

Examined infant verbal and nonverbal cognitive development for 1,937 pairs of same-sex 2-year-old twins. Found that verbal and nonverbal development correlated .42. Genetic factors were responsible for less than half of this phenotypic correlation. The genetic correlation between verbal and nonverbal abilities was only .30, suggesting that genetic effects on verbal and nonverbal abilities are largely independent in infancy. (Author/KB)

Parents of Swedish twin pairs ages 7 to 9 years and of British twin pairs ages 8 to 16 years completed the Child Behavior Checklist. Found that genetic factors influenced aggressive antisocial behavior to a greater extent than nonaggressive antisocial behavior, which was also significantly influenced by the shared environment. There was a significant sex difference in the etiology of nonaggressive antisocial behavior. (Author/KB)

Examined the etiology of individual differences in literacy, phonological awareness, and language ability in monozygotic and dizygotic twins. Found that there was no genetic link between phonological awareness and literacy independent of general language ability. Individual differences in literacy ability were substantially influenced by genetics factors, some of which also act on phonological awareness and general language ability. (Author/KB)

Finds no evidence to counter the assumption that reading begins with a logographic stage; teaching method had a significant impact on children's reading strategies; and several children taught using the whole word technique appeared to exhibit letter-by-letter reading. Suggests that letter-by-letter dyslexia might be an extreme form of a strategy used by normal readers. (RS)

Examines consequences of using alternative definitions for prevalence, sex ratio and heritability. Demonstrates that the characteristics of reading-disabled children vary with the way disability is defined. Concludes that the use of regression-based procedures for identifying reading disability is desirable. Suggests insufficient evidence exists to justify adoption of separate regression procedures for the two sexes. (RS)

Investigates genetic influences on reading in a sample of 285, 13-year-old twins. Finds the heritability of disability for reading recognition to be nonsignificant but that spelling had a substantial genetic contribution to all levels of disability. Suggests two possible independent aspects of phonological ability, each influenced by genetic factors. (RS)