Neurological subtle signs and cognitive development: a study in late childhood and adolescence.

INTRODUCTION AND AIM: Neurological subtle signs (NSS) are often observed during the neurological examination of children and tend to disappear with age. Their persistence into late adolescence or young adulthood has been related to psychiatric and neurocognitive disorders. To provide a better understanding of their functional basis, a longitudinal correlational study with neurocognitive measurements was performed. METHOD: We conducted multiple regression and correlation analyses of NSS with demographic and cognitive measures on a subset of 341 healthy children (56% males), taking part in a longitudinal dental study. Participants, whose ages ranged between 11-15 years, at first evaluation, undertook yearly, during 5 years, a 6-item NSS exam (producing a total score ranging between 0-18) and a comprehensive battery of neurocognitive tests. Effects of age, gender, IQ, and 7 neurocognitive factors on NSS were analyzed. RESULTS: Over the years, NSS scores correlated consistently with selective attention (Stroop test), motor speed (finger tapping), and visuomotor speed (pegboard speed). DISCUSSION: These results suggest that the disappearance of NSS in late childhood and adolescence occurs primarily in parallel with the development of motor and visuomotor functions and secondarily in relation to higher order functions such as selective attention (Stroop) and executive control (B-A Trails difference).

Neurocognitive correlates of positive and negative perfectionism.

The present study examined the neurocognitive correlates of positive and negative perfectionism. A clinical sample of 160 patients undergoing standard neuropsychological testing was administered the Positive and Negative Perfectionism Scale (PANPS), a 40-item questionnaire measure of positive and negative perfectionism. The main question addressed in the study was how individual differences in positive and negative perfectionism relate to differences in neurocognitive performance. The general hypotheses to be tested were that positive perfectionism would be associated primarily with tests that relied on mental and physical "effort," while negative perfectionism would be associated with tests involving both "speed and accuracy." The results of the study provided general support for these hypotheses. Implications for the perfectionism literature and sports psychology are briefly discussed.

The serial use of child neurocognitive tests: development versus practice effects.

When serial neurocognitive assessments are performed, 2 main factors are of importance: test-retest reliability and practice effects. With children, however, there is a third, developmental factor, which occurs as a result of maturation. Child tests recognize this factor through the provision of age-corrected scaled scores. Thus, a ready-made method for estimating the relative contribution of developmental versus practice effects is the comparison of raw (developmental and practice) and scaled (practice only) scores. Data from a pool of 507 Portuguese children enrolled in a study of dental amalgams (T. A. DeRouen, B. G. Leroux, et al., 2002; T. A. DeRouen, M. D. Martin, et al., 2006) showed that practice effects over a 5-year period varied on 8 neurocognitive tests. Simple regression equations are provided for calculating individual retest scores from initial test scores.

A longitudinal factor analytic study of children's neurocognitive abilities.

The neurocognitive abilities of 503 Portuguese children aged 8-11.9 years at onset of the study were assessed annually for 8 years in 3 functional domains: memory, motor and visual motor functions, and attention. A series of exploratory principal axis factor analyses, with varimax rotation, revealed seven factors: Divided Attention, Selective Attention, Verbal Learning and Recall, Visual Learning and Recall, Motor Speed, Visual-Motor Speed, and Working Memory. The same factors emerged across the 8-year period, suggesting that children's neurocognitive structures are articulated and stable throughout this period of development. From these exploratory analyses a small set of cost-effective neuropsychological tests were found to characterize children's functioning consistently throughout the 8-year period.

Repeat test scores on neurobehavioral measures over an eight-year period in a sample of Portuguese children.

Normative data were collected on a sample of 503 Portuguese children who were taking part in a dental study. At the outset, the children were aged 8-11.9 years, with an average of just over 10. A standard battery of neurobehavioral tests covering learning and memory, visual-motor function, and attention was administered at baseline and during seven subsequent years. Normative test data are presented separately by gender and by age at study inception (younger versus older). Results provide normative data for use in clinical settings, where dissociations in performance between cognitive domains need to be identified for diagnostic and therapeutic purposes.

The association of dental caries with blood lead in children when adjusted for IQ and neurobehavioral performance.

UNLABELLED: Associations between childhood lead exposures and dental caries in children have been reported for over 30 years, with widely varying findings and conclusions, and using measures of lead exposure which ranged from food sources and water to tooth, hair or blood lead concentrations. OBJECTIVES: This study examined the relationship of lead exposure and dental caries in a population of normatively healthy children. METHODS: This cross-sectional study used a population of 507 children aged 8-12 who were participating in a clinical trial of dental materials to examine the relationship between lead and caries. Blood lead concentrations and dental caries were examined for association in both primary and permanent teeth. Because it is possible that neurobehavioral status could be associated with both lead exposure and dental caries prevalence, we also examined neurobehavioral status of the subjects. RESULTS: A gender-specific association (males only) between lead exposure and dental caries was found in primary teeth only. Neurobehavioral measures and IQ were not associated with caries status in this population. CONCLUSIONS: This study did not support neurobehavioral status as mediating any association between lead exposure and caries in a normatively healthy population. A gender-specific association between lead and caries not previously reported was found in primary teeth, and no biological explanation for this has been suggested. We conclude that this study provides only weak evidence, if any, for an association of low-level lead exposure with dental caries.

Neurobehavioral effects of dental amalgam in children: a randomized clinical trial.

CONTEXT: Dental (silver) amalgam is a widely used restorative material containing 50% elemental mercury that emits small amounts of mercury vapor. No randomized clinical trials have determined whether there are significant health risks associated with this low-level mercury exposure. OBJECTIVE: To assess the safety of dental amalgam restorations in children. DESIGN: A randomized clinical trial in which children requiring dental restorative treatment were randomized to either amalgam for posterior restorations or resin composite instead of amalgam. Enrollment commenced February 1997, with annual follow-up for 7 years concluding in July 2005. SETTING AND PARTICIPANTS: A total of 507 children in Lisbon, Portugal, aged 8 to 10 years with at least 1 carious lesion on a permanent tooth, no previous exposure to amalgam, urinary mercury level <10 microg/L, blood lead level <15 microg/dL, Comprehensive Test of Nonverbal Intelligence IQ > or =67, and with no interfering health conditions. INTERVENTION: Routine, standard-of-care dental treatment, with one group receiving amalgam restorations for posterior lesions (n = 253) and the other group receiving resin composite restorations instead of amalgam (n = 254). MAIN OUTCOME MEASURES: Neurobehavioral assessments of memory, attention/concentration, and motor/visuomotor domains, as well as nerve conduction velocities. RESULTS: During the 7-year trial period, children had a mean of 18.7 tooth surfaces (median, 16) restored in the amalgam group and 21.3 (median, 18) restored in the composite group. Baseline mean creatinine-adjusted urinary mercury levels were 1.8 microg/g in the amalgam group and 1.9 microg/g in the composite group, but during follow-up were 1.0 to 1.5 microg/g higher in the amalgam group than in the composite group (P<.001). There were no statistically significant differences in measures of memory, attention, visuomotor function, or nerve conduction velocities (average z scores were very similar, near zero) for the amalgam and composite groups over all 7 years of follow-up, with no statistically significant differences observed at any time point (P values from .29 to .91). Starting at 5 years after initial treatment, the need for additional restorative treatment was approximately 50% higher in the composite group. CONCLUSIONS: In this study, children who received dental restorative treatment with amalgam did not, on average, have statistically significant differences in neurobehavioral assessments or in nerve conduction velocity when compared with children who received resin composite materials without amalgam. These findings, combined with the trend of higher treatment need later among those receiving composite, suggest that amalgam should remain a viable dental restorative option for children. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00066118.

The consequences of idiopathic partial epilepsies in relation to neuropsychological functioning: a closer look at the associated mathematical disability.

Although the seizure prognosis is mostly favorable in idiopathic partial epilepsies, there is some empirical evidence showing that subtle neuropsychological impairments, with a consequent risk of academic underachievement, are not rare. We investigated neuropsychological functioning including attention, memory, visuomotor ability, and executive functioning with a closer look at the associated mathematical ability in patients with idiopathic partial epilepsies. A battery of age-appropriate, neuropsychological and mathematics achievement tests was administered to 30 participants with idiopathic partial epilepsy [13 children with benign epilepsy with centrotemporal spikes (BECTS), 17 children with idiopathic childhood occipital epilepsies (ICOE)], and to 30 healthy participants matched for age, sex, handedness, and socioeconomic status. Results did not support any impairment in overall neuropsychological functioning in participants with idiopathic partial epilepsies, whereas, isolated deficits did exist. The mean performance of the IPE group was significantly lower than the control group in six out of 12, neuropsychological measures: drawing (p < 0.01), digit span (p < 0.05), verbal learning (p < 0.01), object assembly (p < 0.01), similarities (p < 0.05), and vocabulary (p < 0.001). Results suggested that one should be cautious regarding neuropsychological and academic prognosis in the so-called benign idiopathic partial epilepsies of childhood.

Age and sex differences in neurobehavioral performance: a study of Portuguese elementary school children.

In this study normative data were obtained on measures of IQ, visual/motor, motor and memory functions among Portuguese elementary school children. Subjects were 228 females and 275 males, 8.0 to 11.9 years of age, in grades 2 through 4, who participated in a dental study. Performance on all tests improved with increasing age. Females performed better in rote verbal learning, psychomotor speed, and speed of information processing. Males had higher scores on tests of visual learning, visual memory, and fine motor speed and coordination. Nonverbal IQ had a significant impact on all tests except motor speed and coordination. Results represent an initial attempt to evaluate Portuguese children in educational and medical settings.

Issues in design and analysis of a randomized clinical trial to assess the safety of dental amalgam restorations in children.

The Casa Pia Study of the Health Effects of Dental Amalgams in Children is a randomized clinical trial designed to assess the safety of low-level mercury exposure from dental amalgam restorations in children. It is being carried out in 507 students (8 to 12 years of age at enrollment) of the Casa Pia school system in Lisbon, Portugal, by an interdisciplinary collaborative research team from the University of Washington (Seattle) and the University of Lisbon, with funding from the National Institute of Dental and Craniofacial Research. Since the goal of the trial is to assess the safety of a treatment currently in use, rather than the efficacy of an experimental treatment, unique design issues come into play. The requirements to identify as participants children who have extensive unmet dental treatment needs and who can be followed for 7 years after initial treatment are somewhat in conflict, since those with the most treatment needs are usually in lower socioeconomic categories and more difficult to track. The identification of a primary study outcome measure around which to design the trial is problematic, since there is little evidence to indicate how health effects from such low-level exposure would be manifested. The solution involves the use of multiple outcomes. Since there are concerns about safety, multiple interim comparisons over time between treatment groups are called for which, in conjunction with the use of multiple outcomes, require an extension of statistical methodology to meet this requirement. Ethical questions that have to be addressed include whether assent of the children participating is required or appropriate, and whether the director of the school system, who is the legal guardian for approximately 20% of the students who are wards of the state and live in school residences, should provide consent for such a large number of children. Approaches taken to address these and other design issues are described.