Preliminary Evidence for a Positive Relation Between the COMT rs4680 Met/Met Genotype and Math Achievement.

To identify if COMT polymorphisms interact with executive functions as predictors of math skills, we assessed 38 adolescents (mean age = 16.4 ± 0.80 years, IQ > 80) from a larger study of high-school students screened for their mathematical abilities. Adolescents were genotyped for the COMT Val158Met polymorphism (grouped as Met/Met or Val-carriers) and completed the WRAT math achievement test, working-memory, inhibitory-control, and shifting tasks. Met/Met-carriers achieved higher WRAT scores than the Val-carriers (W = 229, p = .009). Genotype group was a moderate-to-strong predictor of WRAT scores (ß = 0.56 to 0.74). No genotype/executive-function interaction was detected. Our findings suggest that the rs4680 Met/Met genotype is positively associated with math achievement.

Utility for Clinical Practice of a Bifactor ADHD Model in an Elementary School Population in Mexico.

We assessed the appropriateness of the bifactor model for a Mexican ADHD symptom questionnaire (BMQ-ADHD) applied to parents and teachers of elementary school children. With a sample of 765 reports of children's behavior (48.7% with ADHD A1 criteria, 42.6% girls, mean age 8.5 years [± 1.6 sd]), we examined construct validity, measurement invariance, differences for gender and school level, and the appropriateness of using summed scores. The BMQ-ADHD questionnaire was characterized by good construct validity for the bifactor model for parents' and teachers' reports. For both corpora, we detected invariance for gender and school level. There were differences in ADHD symptoms by gender, but not by school year. The summed scores may represent the factors accurately for females but may present difficulty for males in the parents' questionnaires. The present study revealed good BMQ-ADHD psychometric properties for a unidimensional-hierarchical ADHD scale segregated by gender for parents' and teachers' reports.

The Eyes Have It: A Meta-analysis of Oculomotor Inhibition in Attention-Deficit/Hyperactivity Disorder.

BACKGROUND: Diminished inhibitory control is one of the main characteristics of attention-deficit/hyperactivity disorder (ADHD), and impairments in oculomotor inhibition have been proposed as a potential biomarker of the disorder. The present meta-analysis summarizes the effects reported in studies comparing oculomotor inhibition in ADHD patients and healthy control subjects. METHODS: Inhibitory outcomes were derived from oculomotor experimental paradigms including the antisaccade (AS), memory-guided saccade, and prolonged fixation tasks. Temporal and spatial measures were also extracted from these tasks and from visually guided saccade tasks as secondary outcomes. Data were available from k = 31 studies (N = 1567 participants). Summary effect sizes were computed using random-effects models and a restricted maximum-likelihood estimator. RESULTS: Among inhibitory outcomes, direction errors in AS, after correcting for publication bias, showed a moderate effect and large between-study heterogeneity (k = 18, n = 739, g = 0.57, 95% confidence interval [CI] [0.27, 0.88], I2= 74%); anticipatory saccades in memory-guided saccade showed a large effect and low heterogeneity (k = 11, n = 487; g = 0.86, 95% CI [0.64, 1.08], I2 = 17.7%); and saccades during prolonged fixation evidenced large effect size and heterogeneity (k = 6, n = 325 g = 1.11, 95% CI [0.56, 1.65], I2 = 79.1%) partially related to age. Among secondary outcomes, saccadic reaction time in AS (k = 22, n = 932, g = 0.34, 95% CI [0.06, 0.63], I2 = 53.12%) and coefficient of variability in visually guided saccade (k = 5, n = 282, g = 0.53, 95% CI [0.28, 0.78], I2 = 0.01%) indicated significant effects with small to moderate effects sizes. CONCLUSIONS: ADHD groups commit more oculomotor inhibition failures than control groups. The substantial effects support the conclusion that oculomotor disinhibition is a relevant ADHD-related mechanism. Moderate effects observed in saccadic reaction time variability suggest that fluctuant performance in oculomotor tasks is another relevant characteristic of ADHD.

Parietal and hippocampal hyper-connectivity is associated with low math achievement in adolescence - A preliminary study.

Mathematical cognition requires coordinated activity across multiple brain regions, leading to the emergence of resting-state functional connectivity as a method for studying the neural basis of differences in mathematical achievement. Hyper-connectivity of the intraparietal sulcus (IPS), a key locus of mathematical and numerical processing, has been associated with poor mathematical skills in childhood, whereas greater connectivity has been related to better performance in adulthood. No studies to date have considered its role in adolescence. Further, hippocampal connectivity can predict mathematical learning, yet no studies have considered its contributions to contemporaneous measures of math achievement. Here, we used seed-based resting-state fMRI analyses to examine IPS and hippocampal intrinsic functional connectivity relations to math achievement in a group of 31 adolescents (mean age = 16.42 years, range 15-17), whose math performance spanned the 1% to 99% percentile. After controlling for IQ, IPS connectivity was negatively related to math achievement, akin to findings in children. However, the specific temporo-occipital regions were more akin to the posterior loci implicated in adults. Hippocampal connectivity with frontal regions was also negatively correlated with concurrent math measures, which contrasts with results from learning studies. Finally, hyper-connectivity was not a global feature of low math performance, as math performance did not modulate connectivity of Heschl's gyrus, a control seed not involved in math cognition. Our results provide preliminary evidence that adolescence is a transitional stage in which patterns found in childhood and adulthood can be observed; most notably, hyper-connectivity continues to be related to low math ability into this period.

Do Teachers Confirm Parent's Ratings of ADHD DSM-IV Criteria? A Study of a Mexican Population.

BACKGROUND AND OBJECTIVE: Collecting information from different raters is important for diagnosing ADHD, but several factors can lead to gathering discrepant information. Our aim was to determine the agreement between parent and teacher's when rating the list of ADHD symptoms (criterion A, DSM-IV) in a sample of Mexican school-age children. We explored whether inter-rater agreement varied by children's age and sex, and each symptom of inattention, hyperactivity, and impulsivity. METHODS: A total of 789 children (335 girls) from six elementary school grades grouped as G1 [grades 1-2], G2 [grades 3-4], and G3 [grades 5-6]) were rated by their parents and teachers. We identified inter-rater reliability by using Cohen's kappa coefficient by school level, sex, and ADHD symptoms. We explored the presence of symptoms considering parents' and teachers' ratings, individually and collapsed, using the AND/OR rules. RESULTS: Low inter-rater agreement was observed. Moderate levels were observed in G1, but not in G2 or G3. Both groups of informants reported that more boys than girls met these criteria, but agreement by sex was still low, as were the results of the analyses by individual symptoms. Among the children that met the ADHD criteria, an inattention symptom was the one most frequently reported by both raters, whereas among non-ADHD children, a hyperactive symptom was the one most often reported. DISCUSSION: The exclusive use of questionnaires fails to provide convergent information between raters. We highlight the importance of conducting comprehensive clinical histories when diagnosing ADHD in order to explore what these discrepancies show about the relationship symptoms/context.

Anticipatory oculomotor responses in parents of children with attention deficit hyperactivity disorder.

OBJECTIVE: Diminished inhibitory control has been proposed as a core characteristic and potential endophenotype of attention deficit hyperactivity disorder (ADHD). If this is the case, one would expect to find this trait among first-degree relatives of individuals with ADHD. The aim of this study, therefore, was to determine whether the oculomotor measures typically related to inhibitory control failures in individuals with ADHD are also observed among those relatives. METHODS: Using prosaccadic and antisaccadic tasks in gap and overlap conditions, we assessed a group of unaffected parents of children with ADHD symptoms and compared them to a group of unaffected parents of children with typical development. Direction errors, anticipatory errors and saccadic reaction times were analyzed. We also determined the presence of ADHD behaviors (in adulthood and childhood) in all participants. RESULTS: No between-group differences were observed for the antisaccadic measures, but the group of parents of children with ADHD made more anticipatory responses on the prosaccadic-gap task than the parents of controls. A moderate association between these anticipatory errors and dimensional inattention scores was also found. CONCLUSIONS: Saccadic performance differed between the two groups of parents, as those with children with ADHD showed a failure to withhold the initiation of responses in the absence of external control references (gap condition) on tasks with low cognitive load (prosaccadic). These anticipatory responses were related to inattention traits. Our results support the familial compound of ADHD as a multifactorial disorder.

The Influence of Empathy Trait and Gender on Empathic Responses. A Study With Dynamic Emotional Stimulus and Eye Movement Recordings.

Previous studies have suggested that empathic process involve several components such as cognitive empathy, affective empathy, and prosocial concern. It has also been reported that gender and empathy trait can influence empathic responses such as emotional recognition, which requires an appropriate scanning of faces. However, the degree to which these factors influence the empathic responses, which include emotion recognition, affective empathy, and cognitive empathy, has not yet been specified. Aim: The aim of the present study was to identify the differences between individuals with high and low level of empathy trait, as well as differences between men and women, in an explicit task in order to evaluate the empathic responses. Methods: With this goal in mind, we recorded eye movements during the presentation of dynamic emotional stimuli (joy, anger, fear, and neutral videos). After watching each video, participants had to rate the valence and arousal dimensions of emotional content and explicit empathy responses were assessed. Thirty participants (15 women) were included in a High Empathy group (HE; mean age = 21.0) and 30 participants (16 women) in the Low Empathy group (LE; mean age = 21.2), according to their scores in the Interpersonal Reactivity Index (IRI) scale. Results: As expected, the HE group showed higher scores than the LE group in the explicit empathy responses. These differences, based on global scores, were mainly explained by affective empathy and cognitive empathy responses but not by emotional recognition one. No differences were observed by gender in these measures. Regarding eye movements in the dynamic emotional stimuli, HE group had longer fixation duration on the eyes area than LE group. In addition, women spent more time on the eyes area in comparison to men. Discussion: Our findings suggest that both men and women with high empathy trait are more accurate to empathizing but not on the basis of the emotional recognition response. The fact that women spent more time on the eyes area did not seem to affect the empathic responses to the dynamic emotional stimulus. Overall, empathic responses of both men and women are modulated by their empathic trait. In addition, empathic trait and gender seem to impact strategies to deal with emotional facial information.

The contributions of executive functions to mathematical learning difficulties and mathematical talent during adolescence.

Are mathematical learning difficulties caused by impairment of the abilities that underlie mathematical talent? Or are mathematical difficulties and talent qualitatively different? The main goal of this study was to determine whether mathematical learning difficulties are explained by the same executive functions as mathematical talent. We screened a pool of 2,682 first-year high school students and selected 48 for evaluation, dividing them into three groups: those with mathematical learning difficulties (n = 16), those with typical performance (n = 16), and those with mathematical talent (n = 16). Adolescents from the learning difficulties and talented groups had age, reading skills, and verbal and non-verbal intelligence that were similar to those of the typical performance group. Participants were administered a suite of tasks to evaluate verbal and visual short-term memory and executive functions of inhibition, shifting, and updating. Different executive functions showed different contributions at the two ends of the math ability continuum: lower levels of performance in updating visual information were related to mathematical learning difficulties, while greater shifting abilities were related to mathematical talent. Effect sizes for the differences in performance between groups were large (Hedges' g > 0.8). These results suggest that different executive functions are associated with mathematical learning difficulties and mathematical talent. We discuss how these differences in executive functions could be related to the different types of mathematical abilities that distinguish the three groups.

"Like parent, like child": Attention deficit hyperactivity disorder-like characteristics in parents of ADHD cases.

The objective of this study was to characterize an attention deficit hyperactivity disorder (ADHD) endophenotype in non-affected parents of adolescents with a history of ADHD, based on the relationship between performance on a sustained attention test (continuous performance task, or CPT) and polymorphisms of the DRD4 gene. In a sample of 25 non-affected parents of adolescents with ADHD history obtained from a longitudinal study of a nonclinical population, and 25 non-affected parents of adolescents with no ADHD history, four groups were evaluated with respect to the presence or absence of the long allele polymorphism of the DRD4 gene (i.e., over seven repeats). Comparisons of CPT performance among the four study groups included the number of commission errors, the number of omission errors, mean reaction time on correct responses (MRT), and reaction time (RT) variability (mean standard deviation of RT in each block [SDRT, as variability], and the sigma and tau components of the ex-Gaussian approach). The group of non-affected parents of adolescents with ADHD history and at least one long allele of the DRD4 gene showed greater RT variability (measured by SDRT), which is best explained by the greater frequency of abnormally slow responses (measured by tau). An association between the presence of the long allele of the DRD4 gene polymorphism and ADHD-like failure in CPT performance was evident in the non-affected parents of adolescents with ADHD in childhood. These findings suggest that certain traits of CPT performance could be considered an ADHD endophenotype.

Educational and Cognitive Predictors of Pro- and Antisaccadic Performance.

Voluntary gaze control allows people to direct their attention toward selected targets while avoiding distractors. Failure in this ability could be related to dysfunctions in the neural circuits underlying executive functions. Interestingly, recent evidence suggests that factors such as years of schooling and literacy may positively influence goal-directed behavior and inhibitory control. However, we do not yet know whether these factors also have a significant impact on the inhibitory control of oculomotor responses. Using pro- and antisaccadic tasks to assess the behavioral responses of healthy adults, we tested the contribution of years of schooling and reading proficiency to their oculomotor control, while simultaneously analyzing the effects of other individual characteristics related to demographic, cognitive and motor profiles. This approach allowed us to test the hypothesis that schooling factors are closely related to oculomotor performance. Indeed, a regression analysis revealed important contributions of reading speed and intellectual functioning to the choices on both pro- and antisaccadic tasks, while years of schooling, age and block sequence emerged as important predictors of the kinematic properties of eye movements on antisaccadic tasks. Thus, our findings show that years of schooling and reading speed had a strong predictive influence on the oculomotor measures, although age and order of presentation also influenced saccadic performance, as previously reported. Unexpectedly, we found that an indirect measure of intellectual ability also proved to be a good predictor of the control of saccadic movements. The methods and findings of this study will be useful for identifying and breaking down the cognitive and educational components involved in assessing voluntary and automatic responses.

Características del trastorno por déficit de atención e hiperactividad en escolares mexicanos de acuerdo con la percepción de los padres / Attention deficit-hyperactivity disorder traits among Mexican school-age children according to parents perception

El trastorno por déficit de atención e hiperactividad (TDAH) es uno de los trastornos del neurodesarrollo que más se detectan en la infancia. El objetivo del presente estudio fue estimar la prevalencia del TDAH en una muestra de niños mexicanos de edad escolar. Se estudiaron 6639 alumnosde escuelas públicas de Guadalajara, Jalisco, México, a los que se les levantó una encuesta con el informe de los padres en un cuestionario diseñado bajo los criterios que el DSM-IV considera para el diagnóstico de TDAH. Se re cuperaron y analizaron 4399 cuestionarios. De acuerdo con el informe de los padres, el 8.9% de los niños tienen un perfil de conductas compatibles con los criterios del DSM-IV para el diagnóstico de TDAH. La proporción masculino: femenino fue de 2:1. La distribución por subtipos fue: 147 escolares con tipo combinado, 132 inatento y 114 del tipo hiperactivo-impulsivo. La prevalencia fue mayor del primero al tercer grado que del cuarto al sexto. La prevalencia de TDAH calculada se encuentra dentro del rango informado en otros países. Los estudios realizados en grandes muestras son útiles para diseñar estrategias de intervención acordes a la población en cuestión.

Attention deficit with hyperactivity disorder (ADHD) is one of the most frequent neuro developmental disorders identified in children. The aim of this study was to estimate the prevalence of ADHD behaviour in a sample of Mexican school-aged children. Data were obtained from 6639 pupils enrolled in public elementary schools in Guadalajara, Jalisco, Mexico. Prevalence was based on parental reports collected using the full DSM-IV criteria. A total of 4399 questionnaires were received and analysed. According to the parents, 8.9% of the children met the DSM-IV ADHD criteria. The male: female ratio was 2:1. Distribution by subtypes was as follows: 147 children with combined type, 132 inattentive children, and 114 with the hyperactive-impulsive type. Prevalence was higher from first grade to third grade than it was from fourth to sixth grade. The calculated ADHD prevalence is consistent with the range reported by other countries. Studies conducted with large samples are useful in the design of intervention strategies in accordance with the target population.