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.

Linear and Nonlinear Effect of Years of Schooling, Sex, and Age on the CERAD-MX and Complementary Tasks in a Mexican Sample: A Cross-Sectional Study.

OBJECTIVE: Since evidence of adults' cognition decline is based on standardized testing, we developed regression-based continuous norms by linear regression (LR) and nonlinear quantile regression (NQR) with years of schooling (YoS), age, and sex as covariates on the Mexican adaptation of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD-MX) and complementary tasks. METHODS: 392 healthy, Spanish-speaking Mexican adults (50.25% women) aged 18-59 completed the 15 CERAD-MX cognitive tasks and complementary tasks. We used raw scores and examined YoS-related effects considering sex and age as covariates. For the NQR, we used calibrated scores for sex and age. While LR represents one line across the performance, NQR differentiated several nonlinear performance bands by quantiles. RESULTS: LR showed positive relationships between YoS and cognitive performance with a funnel variance pattern. Therefore, this relationship is better represented with NQR than LR. A small, but significant, negative effect of age was found for this age range (18-59 years). The band with fewer years of schooling (1-6) showed greater variability in the cognitive measures than those with more years of schooling (16-22). CONCLUSION: This study shows that NQR is useful for accurately positioning participants' performance relative to their peers. NQR accounts more than LR for the inconsistent variability of cognitive performance as a function of YoS by identifying the variability according to YoS (low, medium, high). Thus, NQR represents an appropriate way to construct norms for the cognitive performance of adults.

Attitudes about involvement in hypothetical clinical trial protocols in Mexican and Mexican-American at risk for autosomal dominant Alzheimer's disease.

BACKGROUND: The enrollment into clinical trials of persons at risk for autosomal dominant Alzheimer's disease (ADAD) in whom the onset of disease can be accurately predicted facilitates the interpretation of outcomes (e.g., biomarkers, treatment efficacy). Attitudes toward involvement in such studies are biased by intrinsic cultural and social characteristics. Our objective was to study how demographic factors such as country of residence, age, sex, schooling, parenthood, and urbanization affect attitudes towards participation in hypothetical clinical trials in Mexican families at risk for ADAD living either in Mexico or in the United States. METHODS: Participants were 74 members of different families known to harbor an ADAD mutation living in Mexico (n = 50) or in the United States (n = 24). Participants were asked, in a written questionnaire, their interest in participating in four hypothetical clinical trial scenarios of increasing perceived invasiveness. The questionnaire then asked about their willingness should there be a 50% chance of being assigned to a placebo group. The influences of demographic variables on decisions were performed using Wilcoxon rank-sum for continuous variables and Fisher's exact test for categorical variables. RESULTS: Participants who live in Mexico, who have or plan to have children, who do not attend or do not plan to attend school, and who live in rural areas gave more positive responses regarding their willingness to participate compared to those living in the U.S. The 50% chance of being in a placebo group increased the willingness to participate for family members living in Mexico. The main reason for participation was to help future generations, while the main reasons for refusal were not wanting to undergo genetic testing and consideration of adverse effects. CONCLUSIONS: We found a higher level of willingness to participate in clinical trials among persons living in rural Mexico and our data suggest that altruism towards future generations is a major motivation, though this was balanced against concerns regarding side effects. Our results emphasize the importance of sharing information and assessing its understanding in potential participants with diverse backgrounds in the nature of ADAD and regarding the design of clinical trials prior to their enrollment in such studies.

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.

Clustering of neuropsychological traits of preschoolers.

Neuropsychological tests (targeting cognitive, linguistic, motor, and executive abilities) are grouped in neuropsychological domains that are thought to be stable through adulthood. However, this assumption does not always hold true, particularly during young children's early developmental phase. Here, we explored how the neuropsychological profile of typical Spanish-speaking preschoolers varied and consolidated with age. We recruited 643 monolingual Latin-American children from Mexico, Colombia, and Guatemala, with ages spanning from 30 to 71 months of age, and applied a novel neuropsychological examination which combined a total of 52 tests covering five classical neuropsychological domains: receptive, expressive, attention/memory, processing, and executive functions. These tests' scores uncovered a correlational structure across neuropsychological functions that could not be explained by chance. Notably, these correlations' overall strength, but not their interdependence across domains, dramatically increased with age. Moreover, by applying conventional clustering techniques to classify the experimental data, we found a stable representation of two clusters of children with distinctive traits, with cultural factors contributing to this classification scheme. We also found that the tasks were well organized in a network of abilities, where nodes with highest highest interconnectedness were those that required multimodal processing. These results contribute to our understanding of children's 'normal' development and could help identify how failure in particular functions forecasts the emergence of neurodevelopmental disorders. Our analytic methods might become useful to characterize individual differences and improve educational practices and interventions.

Effects of the Age, Sex, and Maternal Education of Monolingual Spanish-Speaking Preschool Children on Oral Narrative Production.

Purpose The aim of the present cross-sectional study was to determine the effects of age, sex, and maternal education of monolingual Spanish-speaking preschoolers on both macrostructural (oral narrative quality) and microstructural measures (number of different words, communication units, mean length of utterance in both words and morphemes, and number of conjunctions) of their oral narrative production. Method A total of 277 monolingual Spanish-speaking Mexican children aged 2;06-5;11 (years;months) and divided into four age groups (ages 2, 3, 4, and 5 years) were asked to retell a fictional story from the oral narrative ability task of the Evaluación Neuropsicológica Infantil-Preescolar. Results Appropriate internal consistency and interrater reliability were demonstrated. Pearson correlations between macro- and microstructural measures showed a positive association. A multivariate analysis of variance revealed a main effect for age, but not for sex, maternal education, or between-variables interactions. Partial eta-squared showed that age had a medium effect size on oral narrative quality and the number of different words and conjunctions, with a small effect size on communication units and mean length of utterance in words and morphemes. Hierarchical multiple regression analyses indicated that age explained the largest percentage of variance across the oral narrative measures. Conclusions The measures found to be most sensitive to the effect of age (number of different words, oral narrative quality, communication units, conjunctions) are also those most easily assessed by clinicians with limited training in linguistics. Results obtained for the number of different words and communication units were similar to those reported previously for English-speaking children.

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.

Efecto de la deficiencia de hierro sobre el desarrollo neuropsicológico en lactantes / Effect of iron deficiency on neuropsychological development in infants

Resumen La deficiencia de hierro (DFe) es la patología nutrimental infantil de mayor prevalencia en el mundo y afecta la maduración cerebral y el consiguiente desarrollo cognitivo, lingüístico, motor y comportamental de quienes la padecen. El informe que se presenta tuvo como objetivo estudiar, en profundidad, literatura acerca del efecto de la DFe sobre el desarrollo neuropsicológico en lactantes. Para ello, se analizaron 51 estudios originales realizados en humanos, 49 de los cuales fueron obtenidos a través de Pubmed y 2, de Scielo. Cabe resaltar que, con el fin de discutir los hallazgos de estos artículos, se incluyeron investigaciones sobre el efecto de la DFe que utilizan modelo animal, así como estudios en humanos con desarrollo típico. Esta búsqueda se realizó a conveniencia. El reconocimiento de sus implicaciones facilitaría el trabajo terapéutico, así como la inclusión de programas de estimulación temprana junto con el manejo de la deficiencia nutrimental.

Abstract Iron is involved in various aspects related to brain function, including oxygen transport, neurotransmitters metabolism, DNA synthesis, ATP production, dendritic growth, axonal development and transport, myelin production, glial development, in plasticity markers such as the brain-derived growth factor, and in synaptic plasticity. Human development (biological, cognitive, social) is associated with a bidirectional and dynamic interaction between gene activity, neural activity and environment. An environmental variable is nutrition, and it is known that the central nervous system is extremely vulnerable to nutritional deficiencies during pregnancy and in the first two years of life, period in which an accelerated maturational dynamism occurs. Therefore, a disturbance of these by an iron deficiency would result in neuropsychological alterations, with varied expressions depending on the age at which it occurs and the severity and duration of the nutritional disease. Iron deficiency is defined as the depletion of iron reserves in the body by various factors (nutritional, physiological, pathological, etc.). Three stages of the illness have been established: iron depletion, iron deficiency without anemia and iron deficiency anemia. The first is associated with a decrease in iron reserves without reaching the deficiency; it may be due to a reduction in iron intake and or absorption, excessive loss or an increase in iron requirements. At this stage, there are no functional consequences in the organism. The second stage, is characterized by biochemical changes that reflect a pathologically reduced concentration of serum ferritin with a normal hemoglobin concentration. Finally, iron deficiency anemia is defined by the combination of low concentration of serum ferritin and hemoglobin. Given that iron deficiency is the most prevalent childhood nutritional disorder in the world (affecting 43 % of children aged 6-59 months) and that it impacts brain maturation and the consequent cognitive, linguistic, motor and behavioral development of those who suffer from it, in this paper, the literature on the effect of iron deficiency on neuropsychological development in infants is analyzed in depth. The review was performed considering the short, medium and long lasting effects of iron deficiency without anemia, iron deficiency anemia, chronic iron deficiency during the first two years of life and the presence of treatment. To contextualize, the analysis of the relationship between iron and brain functioning is included and the variables that modulate the expression of its effect are addressed. To carry out the search of literature regarding the effect of iron deficiency on neuropsychological development in infants, Pubmed and SciELO were consulted. No date or language restriction was established. Different combinations of terms were used: "iron deficiency infant", "iron deficiency fetal", "iron deficiency neonatal", "iron deficiency long lasting". The analyzed reports fulfilled the following inclusion criteria: a) primary sources, b) establish a value of hemoglobin and at least one of iron (i.e, serum ferritin, mean corpuscular volume, free erythrocyte, protoporphyrin, transferrin saturation) to define the children of each group, c) human sample, d) description of the measures used for the evaluation, e) studies examined after this stage, had to determine that the sample evaluated presented iron deficiency during the first two years of life. In this paper, 51 original articles conducted in humans were analyzed, of which 49 were obtained through Pubmed and 2 from SciELO. It should be noted that, in order to discuss the findings of these reports, literature was included on the effect of iron deficiency using animal models, as well as studies in humans with typical development. The search for these was done at convenience. The recognition of its implications would facilitate the therapeutic work, as well as the inclusion of early stimulation programs together with the management of nutritional deficiency.

A mixed-methods study of cultural beliefs about dementia and genetic testing among Mexicans and Mexican-Americans at-risk for autosomal dominant Alzheimer's disease.

Trials to prevent autosomal dominantly inherited Alzheimer's disease (ADAD) are critical and timely. However, cultural beliefs about AD and genetic testing may preclude informed consent and participation, especially among racial/ethnic minorities. This mixed-methods study examines cultural beliefs about AD and genetic screening among at-risk populations of Mexican heritage. We surveyed 86 Mexican and 37 Mexican-American family members of patients with ADAD and interviewed 18 respondents in Mexico to explore perceptions and knowledge regarding AD and genetic testing. While most respondents understood that AD is inherited in their families, they also had limited understanding of the genetic mechanisms behind AD. Many believed that AD is a normal part of aging or that it is a mental illness caused by bad habits. However, beliefs that AD is caused by a curse or God's will were uncommon. The interviews demonstrated that very few at-risk respondents understood their own risk for harboring the mutation causing AD in their family. Once informed, most expressed a strong interest in genetic testing, largely motivated by the desire to be better prepared for the development of AD. Health professionals treating and investigators enrolling members from families with ADAD cannot assume that they fully understand the nature of the illness; therefore, providers should provide comprehensive information about ADAD and genetic testing.

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.

Relación entre lenguaje expresivo y receptivo y habilidades prelectoras / Relationship between expressive and receptive and pre-reading skills

Resumen El objetivo de este estudio fue establecer las relaciones entre habilidades de lenguaje expresivo y receptivo y habilidades prelectoras en niños en edad preescolar. Usando un diseño metodológico empírico observacional de corte transversal se evaluaron las habilidades de lenguaje oral y habilidades fonológicas a un total de 106 preescolares. Los modelos de regresión multivariante señalan que las habilidades expresivas explican una mayor varianza de habilidades fonológicas implicadas en la detección de rimas y sonidos iniciales de las palabras, precursores importantes para el aprendizaje posterior de la lectoescritura.

Abstract The objective of this study was to establish the relationship of receptive and expressive language abilities with pre-reading skills in preschoolers. An observational and cross-sectional study was carried out by evaluating oral language abilities and phonological skills in a total sample of 106 children. Multivariate regression models pointed out that expressive abilities significantly explain the variance of the phonological skills implied in the detection of rhymes and initial phonemes, which are important precursors for the subsequent literacy learning.

"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.

Development of early numerical abilities of Spanish-speaking Mexican preschoolers: A new assessment tool.

This article presents a tool for assessing the early numerical abilities of Spanish-speaking Mexican preschoolers. The Numerical Abilities Test, from the Evaluación Neuropsicológica Infantil-Preescolar (ENI-P), evaluates four core abilities of number development: magnitude comparison, counting, subitizing, and basic calculation. We evaluated 307 Spanish-speaking Mexican children aged 2 years 6 months to 4 years 11 months. Appropriate internal consistency and test-retest reliability were demonstrated. We also investigated the effect of age, children's school attendance, maternal education, and sex on children's numerical scores. The results showed that the four subtests captured development across ages. Critically, maternal education had an impact on children's performance in three out of the four subtests, but there was no effect associated with children's school attendance or sex. These results suggest that the Numerical Abilities Test is a reliable instrument for Spanish-speaking preschoolers. We discuss the implications of our outcomes for numerical development.

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.

Differential Improvement of Executive Functions During Abstinence in Cocaine-Dependent Patients: A Longitudinal Study.

BACKGROUND: In substance abusers, deficits in executive functioning (EF) are relevant to understanding the behavioral regulation of substance consumption and the failure to remain abstinent. OBJECTIVE: To determine the course of EF impairment, measured with traditional and ecological instruments, after 1 and 3 months of abstinence in patients with cocaine dependence. METHODS: 26 cocaine-only-dependent in-patients (cocaine-dependent group, CDG) and 24 nondependent controls (control group, CG) recruited from a typical population were assessed using several EF tests and questionnaires [Stroop, verbal and graphic fluency, Wisconsin Card-Sorting Test (WCST), Tower of London (TOL), and Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A)] after three periods of abstinence: 1 week, 1 month, and 3 months. RESULTS: At 1 week (baseline), CDG underperformed CG on most EF measures (WCST categories completed; TOL-total number of moves, execution time, and rule violations; and various BRIEF-A subscales). At 1 month, CDG moderately improved its performance on several measures, meanwhile the improvement in the 12 patients who would eventually complete the 3-month abstinence proved particularly significant when compared to their baseline values. In the a posteriori comparison of the baseline values of noncompleters versus completers, scores for the former were lower on the EF tasks, but higher on the BRIEF-A. Both groups, showed significantly worse scores than CG on both instruments. CONCLUSIONS/IMPORTANCE: Cocaine-dependent patients showed marked difficulties in the EF associated mainly with adaptive behavior to their environment. Cocaine-dependent patients with better EF at baseline improved significantly during abstinence and had better treatment adherence. Results suggest that executive improvement and treatment adherence in cocaine abusers in abstinence is related to intrinsic cognitive characteristics of patients.

The relationship between cognitive reserve and the clinical stage of HIV infection.

The objective of this study was to determine whether the effect of cognitive reserve (CR) on neuropsychological functioning differs according to the clinical stage of HIV infection. A sample of 34 HIV-positive individuals aged 23-49, with a minimum of 9 years of formal education, was assessed. Participants were grouped according to the Centers for Disease Control and Prevention's (CDC) clinical stages (A = 10, B = 16, C = 8). CR was calculated for each clinical stage group in accordance with estimates of premorbid IQ, years of education, and occupational attainment. The sum of these three variables was then transformed into z-scores. Individuals above the median were classified as having "High" CR (HCR), those below the median were classified as "Low" CR (LCR). Participants completed an evaluation of cognitive and executive functions based on selected, modified tasks from the HIV University of Miami Annotated Neuropsychological test in Spanish (HUMANS). Assessment included the following domains: attention, memory (visual, verbal, and working memory), executive functions (cognitive flexibility, switching), language (naming), and visual constructive skills (block design). HCR outperformed LCR in all cognitive domains. Comparison of HCR and LCR in each clinical stage revealed that the effect of CR was stronger in stage B than in stages A and C, suggesting that this effect does indeed vary among stages.