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Introduction: Most behavior checklists for attention problems or attention deficit/hyperactivity disorder (ADHD) such as the Child Behavior Checklist (CBCL) have a narrow range of scores, focusing on the extent to which problems are present. It has been proposed that measuring attention on a continuum, from positive attention skills to attention problems, will add value to our understanding of ADHD and related problems. The Strengths and Weaknesses of ADHD symptoms and Normal behavior scale (SWAN) is such a scale. Items of the SWAN are scored on a seven-point scale, with in the middle ‘average behavior’ and on the extremes ‘far below average’ and ‘far above average’. Method: The SWAN and the CBCL were completed by mothers of respectively 560 and 469 12-year-old twin pairs. The SWAN consists of nine DSM-IV items for Attention Deficit (AD) and nine DSM-IV items for Hyperactivity/Impulsivity (HI). The CBCL Attention Problem (AP) scale consists of 11 items, which are rated on a three-point scale. Results: Children who had a score of zero on the CBCL AP scale can be further differentiated using the SWAN, with variation seen between the average behavior and far above average range. In addition, SWAN scores were normally distributed, rather than kurtotic or skewed as is often seen with other behavioral checklists. The CBCL AP scale and the SWAN-HI and AD scale were strongly influenced by genetic factors (73%, 90% and 82%, respectively). However, there were striking differences in genetic architecture: variation in CBCL AP scores is in large part explained by non-additive genetic influences. Variation in SWAN scores is explained by additive genetic influences only. Conclusion: Ratings on the SWAN cover the continuum from positive attention skills to attention and hyperactivity problems that define ADHD. Instruments such as the SWAN offer clinicians and researchers the opportunity to examine variation in both strengths and weaknesses in attention skills. [ABSTRACT FROM AUTHOR]

Background: Activity level is an important component of children's temperament, as well as being part of the core symptom domain of hyperactivity-impulsivity within attention deficit hyperactivity disorder (ADHD). Yet it is poorly understood, due partly to limitations on parent and teacher ratings, which are typically used as measurements of these symptoms. Methods: We aimed to study the etiology of objectively-measured activity level across two situations, using actigraphs. A population-based sample of 463 7–9-year-old twin pairs were assessed individually both when apart undergoing laboratory-based cognitive testing and when together during a break in testing. Results: Heritability of activity level was estimated as 24% during the test session and at 30% during the break in testing. Shared environmental influences accounted for 27% of the variance in activity level during the test session and 42% of activity level measured during the break. A genetic correlation of 1.0 indicated that the same genes influenced activity level across the two situations, justifying the use of a composite measure of the two situations. This produced a heritability estimate of 36%. Conclusions: Objectively-measured activity level shows a moderate degree of genetic influence, with a common set of genes influencing activity level across situations. This supports the use of actigraphs as an additional source of information in studies that aim to improve phenotype definition for molecular genetic studies of activity level and ADHD. [ABSTRACT FROM AUTHOR]

Strategies are discussed for locating and interviewing a community-based sample of 492 adults, approximately half of whom were diagnosed in 1974 with ADHD. Completion rates, reasons for attrition, and amount of time and intensity of effort associated with subject location are reported. We found that 81% of the original sample had been located after 28 months, and that the reconstituted sample closely resembled the original larger childhood sample in background characteristics. Findings confirm that staff persistence was an important factor in containing attrition, and that longer contact intervals are likely to be a necessary feature of follow-up with socially and behaviorally disordered samples. [ABSTRACT FROM AUTHOR]

A random population sample of 1479 Chinese boys from Hong Kong was screened and diagnosed in a two-stage epidemiological study. Four groups, age 7-8, were distinguished: (1) a pure hyperactive group (HA), (2) a mixed hyperactive/conduct-disordered group (HA + CD), (3) a pure conduct-disordered group (CD), and (4) a normal control group (N). On a visual search task, only the HA children showed a specific processing deficit in performance. This confirms the diagnostic value of such a deficit for hyperactivity, differentiating it from conduct disorder. The failure to find a similar deficit in the HA + CD group raises questions concerning the clinical identity of these children. Each group showed a performance decrement over time in the visual search task but the decrement did not differ between the four groups. This observation is not congruent with the reports of a short attention span in hyperactive children; explanations of this apparent contradiction are considered. [ABSTRACT FROM AUTHOR]

A general model for describing the structure of multiple trait measures reported by multiple sources and observed at multiple times is developed. This model is applied to data on conduct disorder/oppositional behaviour, attention deficit and anxiety/withdrawal reported by three sources (child, mother, teacher) at three ages (8, 10 and 12 years) for a birth cohort of 1265 New Zealand children. This model was shown to fit the observed data adequately. The major conclusions of the analysis were: (a) reports of child behaviour derived from a specific source at a given time were of limited validity as measures of the child's behavioural tendencies; (b) reports of child behaviour derived from the same source were subject to correlated errors of measurement; (c) there was evidence of strong correlations ( r=.80-.85) between conduct disorder/oppositional behaviour and attention deficit and weaker correlations ( r=.30) between externalising traits and anxiety/withdrawal; and (d) when due allowance was made for errors of measurement in the report data, conduct disorder/oppositional behaviour, attention deficit and anxiety/withdrawal emerged as having very high stability across measurement periods. The implications of the results for a range of issues relating to the validity of report data, the interpretation of inter-informant correlations, the correlation/comorbidity of child behaviour problems and the stability of behaviour are discussed. [ABSTRACT FROM AUTHOR]

While a number of studies have reported associations between lead levels and cognitive development and behaviour in cross-sectionally studied child samples, there have been relatively few studies of the long term effects of early lead exposure. This issue was studied in a birth cohort of 1265 New Zealand children who were assessed with respect to: (a) dentine lead levels at ages 6-8 years; (b) cognitive and behavioural outcomes at 12, 13 years: (c) various confounding factors. The results of the analysis show: (a) the presence of small but consistent bivariate associations (ranging in absolute size from r=.08 to.20) between early lead levels and later school performance and behaviour; (b) after adjustment fur both errors of measurement in test scores and lead levels and adjustment for confounding factors these correlations reduced to between 07 and 14. Nonetheless these correlations remained statistically significant. The evidence is consistent with the view that early mildly elevated lead levels are associated with small but relatively long term deficits in cognitive ability and attentional behaviours. [ABSTRACT FROM AUTHOR]

A model for estimating possible reciprocal relationships between attention deficit and reading achievement is proposed. This model is fitted to data for a birth cohort of New Zealand children studied at 10 and 12 years on measures of attention deficit and reading achievement. Model estimates suggest that at the age of 12 years the predominant direction of causality is that attention deficits influence reading achievement and there is no evidence to suggest that reading achievement influenced attention deficit levels. The implications of these findings are discussed. [ABSTRACT FROM AUTHOR]

The paper presents four alternative confirmatory factor models to represent the structure of measures of attention deficit and conduct disorder obtained from multiple sources. These models range in complexity from a simple one-factor model with no method effects to a two-factor model with method effects. These models were fitted to data gathered on maternal, teacher and self-report of attention deficit and conduct disorder for a sample of New Zealand children studied at ages 9 and 10 years. The analysis strongly suggests that the best representation of the data was a two-factor model in which there were distinct factors of attention deficit and conduct disorder with these factors being highly correlated ( r= 0.87 - 0.88). It is suggested that the most suitable clinical nomenclature may be to describe conduct disorder and attention deficit generically as externalizing disorders, subscripting this classification with clauses which describe the relative contributions of conduct disorder and attention deficit. The implications of this finding for the measurement, classification and explanation of conduct disorder and attention deficit disorder are discussed. [ABSTRACT FROM AUTHOR]