Pobreza, traumas tempranos, déficit atencional y deserción educacional: un círculo de daño. Lecciones aprendidas en el Programa Soymás, La Pintana / Poverty, early trauma, attention deficit and educational dropout: a circle of harm. Lessons learned in the Soymás Program, La Pintana

El antecedente de maltrato infantil y el Trastorno por Déficit de Atención e Hiperactividad (TDAH), son condiciones que tienen una alta prevalencia en los jóvenes de sectores vulnerables. Analizamos su relación con deserción escolar, que también es mayor en tales contextos. La deserción es un fenómeno multifactorial, influenciado por factores propios del estudiante, de la institución, del contexto familiar y del entorno social. Presentamos hallazgos en la Fundación Soymás, institución de formación para madres adolescentes, localizada en La Pintana, una de las comunas con mayor pobreza en Chile, donde la deserción en 2022 fue 45%. De acuerdo a la encuesta ACES de 10 eventos traumáticos en la niñez, 50% de las estudiantes sufrió 3 o más, y 21% 7 o más. Al menos un 40% de la población cumplía criterios de TDAH y un 30% adicional manifestaba síntomas sugerentes (versus 4,5% de TDAH reportado en adolescentes del país). Constatamos una asociación directa entre las tres variables: Maltrato, TDAH y Deserción. Estos hallazgos deberían ser considerados en políticas públicas, reforzando la necesidad de colaboración entre Salud y Educación.

A history of child abuse and Attention Deficit Hyperactivity Disorder (ADHD) are conditions that have a high prevalence in young people from vulnerable sectors. We analyze its relationship with school dropout, which is also higher in such contexts. Dropout is a multifactorial phenomenon, influenced by factors specific to the student, the institution, the family context, and the social environment. We present findings at the Soymás Foundation, a training institution for adolescent mothers, located in La Pintana, one of the counties with the highest poverty in Chile, where dropout in 2022 was 45%. According to the ACES survey of 10 traumatic events in childhood, 50% of the students suffered 3 or more, and 21% 7 or more. At least 40% of the population met the criteria for ADHD and an additional 30% manifested suggestive symptoms (versus 4.5% of ADHD reported in adolescents in the country). We found a direct association between the three variables: Abuse, ADHD and Desertion. These findings should be considered in public policies, reinforcing the need for collaboration between Health and Education.

Phenotypic variability of GLUT1 deficiency: When is necessary to suspect? / Variabilidad fenotípica del déficit de GLUT1: ¿Cuándo es necesario sospechar?

INTRODUCTION: Glucose Transporter Type 1 Deficiency Syndrome (GLUT1-DS) is caused by the SLC2A1 gene muta tion, which encodes the glucose transporter proteins to the brain Neurological manifestations occur in three main domains: seizures, abnormal movements, and cognitive disorders. The diagnosis is presumed upon the finding of low CSF glucose and confirmed by the gene molecular analysis. Ac curate diagnosis is important because it has a specific treatment, which is ketogenic diet. OBJECTIVE: To analyze two SD-GLUT1 pediatric patients with unusual phenotype. CLINICAL CASE: We present the case of two siblings who presented absence seizures and a paroxysmal movement disorder. Both patients were studied, finding low CSF glucose. The diagnosis of GLUT1-DS was confirmed with molecular analysis. Specific treatment with ketogenic diet achieved good response in both cases. Con clusions: We present their peculiar clinical characteristics that allowed us to suspect this wide phe notypic spectrum. Correct and timely diagnosis and treatment can significantly improve the quality of life of those affected.

Lateral Prefrontal Theta Oscillations Reflect Proactive Cognitive Control Impairment in Males With Attention Deficit Hyperactivity Disorder.

Attention Deficit Hyperactivity Disorder (ADHD) is a common neuropsychiatric disorder in which children present prefrontal cortex (PFC) related functions deficit. Proactive cognitive control is a process that anticipates the requirement of cognitive control and crucially depends on the maturity of the PFC. Since this process is important to ADHD symptomatology, we here test the hypothesis that children with ADHD have proactive cognitive control impairments and that these impairments are reflected in the PFC oscillatory activity. We recorded EEG signals from 29 male children with ADHD and 25 typically developing (TD) male children while they performed a Go-Nogo task, where the likelihood of a Nogo stimulus increased while a sequence of consecutive Go stimuli elapsed. TD children showed proactive cognitive control by increasing their reaction time (RT) concerning the number of preceding Go stimuli, whereas children with ADHD did not. This adaptation was related to modulations in both P3a potential and lateral prefrontal theta oscillation for TD children. Children with ADHD as a group did not demonstrate either P3a or theta modulation. But, individual variation in theta activity was correlated with the ADHD symptomatology. The results depict a neurobiological mechanism of proactive cognitive control impairments in children with ADHD.

Neurocognitive mechanisms underlying working memory encoding and retrieval in Attention-Deficit/Hyperactivity Disorder.

Working memory (WM) impairments in ADHD have been consistently reported along with deficits in attentional control. Yet, it is not clear which specific WM processes are affected in this condition. A deficient coupling between attention and WM has been reported. Nevertheless, most studies focus on the capacity to retain information rather than on the attention-dependent stages of encoding and retrieval. The current study uses a visual short-term memory binding task, measuring both behavioral and electrophysiological responses to characterize WM encoding, binding and retrieval comparing ADHD and non-ADHD matched adolescents. ADHD exhibited poorer accuracy and larger reaction times than non-ADHD on all conditions but especially when a change across encoding and test displays occurred. Binding manipulation affected equally both groups. Encoding P3 was larger in the non-ADHD group. Retrieval P3 discriminated change only in the non-ADHD group. Binding-dependent ERP modulations did not reveal group differences. Encoding and retrieval P3 were significantly correlated only in non-ADHD. These results suggest that while binding processes seem to be intact in ADHD, attention-related encoding and retrieval processes are compromised, resulting in a failure in the prioritization of relevant information. This new evidence can also inform recent theories of binding in visual WM.

Variabilidad fenotípica del déficit de GLUT1: ¿Cuándo es necesario sospechar? / Phenotypic variability of GLUT1 deficiency: when is necessary to suspect?

Resumen: Introducción: La deficiencia del transportador de glucosa tipo 1 constituye un síndrome (SD-GLUT1), provocado por la mutación del gen SLC2A1, que codifica la proteína transportadora de glucosa al encéfalo. Las manifestaciones neurológicas se dan en tres dominios principales: crisis epilépticas, movimientos anormales y alteraciones cognitivas. El diagnóstico se presume ante el hallazgo de hipoglucorraquia y se confirma mediante el análisis molecular del gen. La importancia de precisarlo radica en que tiene tratamiento específico, la dieta cetogénica. Objetivo: Analizar dos casos clínicos de SD-GLUT1 de presentación atípica, destacando la variabilidad del fenotipo. Caso Clínico: Presentamos el caso de dos hermanos cuyas manifestaciones fueron crisis epilépticas de tipo ausencias típicas, y un trastorno paroxístico del movimiento. Los pacientes fueron estudiados encontrándose hipoglucorraquia en ambos y se confirmó diagnóstico de SD-GLUT1 con estudio molecular. El tratamiento específico con dieta cetogénica logró buena respuesta. Conclusiones: Exponemos sus características clínicas peculiares que nos permitieron sospechar este cuadro, de espectro fenotípico amplio, cuyo diagnós tico y tratamiento, correcto y oportuno, puede mejorar significativamente la calidad de vida de los afectados.

Abstract: Introduction: Glucose Transporter Type 1 Deficiency Syndrome (GLUT1-DS) is caused by the SLC2A1 gene muta tion, which encodes the glucose transporter proteins to the brain Neurological manifestations occur in three main domains: seizures, abnormal movements, and cognitive disorders. The diagnosis is presumed upon the finding of low CSF glucose and confirmed by the gene molecular analysis. Ac curate diagnosis is important because it has a specific treatment, which is ketogenic diet. Objective: To analyze two SD-GLUT1 pediatric patients with unusual phenotype. Clinical Case: We present the case of two siblings who presented absence seizures and a paroxysmal movement disorder. Both patients were studied, finding low CSF glucose. The diagnosis of GLUT1-DS was confirmed with molecular analysis. Specific treatment with ketogenic diet achieved good response in both cases. Con clusions: We present their peculiar clinical characteristics that allowed us to suspect this wide phe notypic spectrum. Correct and timely diagnosis and treatment can significantly improve the quality of life of those affected.

A pupil size, eye-tracking and neuropsychological dataset from ADHD children during a cognitive task.

Attention Deficit/Hyperactive Disorder (ADHD) is diagnosed based on observed behavioral outcomes alone. Given that some brain attentional networks involve circuits that control the eye pupil, we monitored pupil size in ADHD- diagnosed children and also in control children during a visuospatial working memory task. We present here the full dataset, consisting of pupil size time series for each trial and subject. There are data from, 22 control, and 28 ADHD-diagnosed children. There are also data from a subset of 17 ADHD children that performed the task twice, on- and off-medication. In addition, our dataset also includes gaze position data from each trial and subject, and also scores from the Weschler Intelligence Scale for Children. In this context, the dataset can serve as a resource to analyze dynamic eye movement and pupil changes as a function of known behavioral changes and scores in neuropsychological tests, which reflect neurocognitive processing.

Diagnósticos diferenciales de trastorno del espectro autista y aporte de ADOS y ADIR-R como herramientas complementarias / Differentials diagnosis of autism spectrum disorders and contribution of ADOS and ADD-R as complementary tools

INTRODUCCIÓN: El diagnóstico de los Trastornos del Espectro Autista (TEA) es clínico y complejo por la dificultad de interpretar los síntomas, las frecuentes comorbilidades, la heterogeneidad clínica y la ausencia de indicadores específicos. Múltiples instrumentos se han desarrollado para su evaluación, destacando la Escala de Observación para el Diagnóstico del Autismo (ADOS) y la Entrevista para Diagnóstico de Autismo, versión revisada (ADI-R); la sensibilidad y especificidad de estos tests es alta, más aún si se utilizan en conjunto. OBJETIVO: Evaluar la utilidad de ADI-R y ADOS como herramientas complementarias para el diagnóstico de TEA, en particular cuando resultan discrepantes del diagnóstico clínico. METODOLOGÍA: Estudio retrospectivo, de revisión de registro clínico de 44 pacientes (36 varones), de edad promedio 6,7 años, por sospecha de TEA entre 6/2015-05/2017. Se aplicó ADI-R+ADOS-2, siendo ciega respecto a la hipótesis clínica inicial. El diagnóstico definitivo se plantea tras el seguimiento de largo plazo (6-58 meses). RESULTADOS: En 37 de 44 pacientes, el diagnóstico clínico inicial fue TEA; en los 7 restantes otros diagnósticos de trastornos del neurodesarrollo y psiquiátricos. ADI-R+ADOS-2 fueron concordantes con el diagnóstico clínico en 39(89%), en 7 descartando y en 32 confirmando el diagnóstico de TEA, añadiendo en estos últimos el grado de severidad. En 5 casos hubo discordancia entre el diagnóstico clínico inicial y los tests; en los 5 casos el especialista planteó TEA y los tests lo refutaron, comprobándose tras la evolución en largo plazo lo planteado por los test en 4 casos y por el clínico en 1 caso. Los más frecuentes diagnósticos diferenciales fueron Trastorno de Comunicación Social, Trastorno por déficit de atención e hiperactividad comórbido con Trastorno del desarrollo de lenguaje y Trastornos ansiosos. CONCLUSIONES: El diagnóstico de TEA debe ser clínico, hecho por un médico especialista que considere una multiplicidad de variables. ADI-R+ADOS2 resultaron herramientas complementarias útiles, particularmente en los casos en que descartaron TEA, instando al equipo tratante a la búsqueda de diagnósticos diferenciales.

INTRODUCTION: The diagnosis of the autism spectrum disorders (ASD) is clinically and complex because of the difficulty of interpreting symptoms, frequent comorbidities, the clinical heterogeneity and the lack of specific indicators. Many instruments have been developed for evaluation, of which we highlight the scale of observation for the diagnosis of autism (ADOS) and the interview for diagnosis of autism, revised (ADI-R); the sensitivity and specificity of these tests is high, even more when they are used together. OBJECTIVE: To evaluate the usefulness of ADI-R and ADOS as complementary tools for the diagnosis of ASD, particularly when they are discrepant from the clinical diagnosis. METHODS: This is a retrospective study, a review of the clinical records of 44 patients (36 male), average age 6.7 years, with a suspicion of ASD between June 2015- May 2017. ADIR+ADOS-2 were applied blindly to the initial clinical hypothesis. The definitive diagnosis is certified after a long-term follow-up (6-58 months). RESULTS: In 37 of 44 patients the initial clinical diagnosis was ASD; in the remaining 7 other psychiatric and neurodevelopmental disorders were diagnosed. ADI-R+ADOS-2 were concordant with the clinical diagnosis in 39 (89%), excluding 7 and in 32 confirming the diagnosis of ASD, adding the degree of severity in the latter. In 5 cases there was discrepancy between the initial clinical diagnosis and tests; in these 5 cases the specialist suspected ASD and the tests disproved it; after the long-term follow-up the test's diagnosis was confirmed in 4 of the 5 cases, and in the remaining case the clinical diagnosis was confirmed. The most frequent differential diagnoses were social communication disorder, attention deficit hyperactivity disorder comorbid with language development disorder, and anxious disorders. CONCLUSIONS: The diagnosis of ASD should be clinical and made by a medical specialist who considers a multiplicity of variables. ADI-R+ADOS2 were complementary tools, particularly in cases in which ASD was rejected, urging the treating team to search for differential diagnosis.

Theta and Alpha Oscillation Impairments in Autistic Spectrum Disorder Reflect Working Memory Deficit.

A dysfunction in the excitatory-inhibitory (E/I) coordination in neuronal assembly has been proposed as a possible neurobiological mechanism of Autistic Spectrum Disorder (ASD). However, the potential impact of this mechanism in cognitive performance is not fully explored. Since the main consequence of E/I dysfunction is an impairment in oscillatory activity and its underlying cognitive computations, we assessed the electroencephalographic activity of ASD and typically developing (TD) subjects during a working-memory task. We found that ASD subjects committed more errors than TD subjects. Moreover, TD subjects demonstrated a parametric modulation in the power of alpha and theta band while ASD subjects did not demonstrate significant modulations. The preceding leads to significant differences between the groups in both the alpha power placed on the occipital cortex and the theta power placed on the left premotor and the right prefrontal cortex. The impaired theta modulation correlated with autistic symptoms. The results indicated that ASD may present an alteration in the recruitment of the oscillatory activity during working-memory, and this alteration could be related to the physiopathology of the disorder.

Lateral prefrontal activity as a compensatory strategy for deficits of cortical processing in Attention Deficit Hyperactivity Disorder.

Attention Deficit Hyperactivity Disorder (ADHD) is the most common neuropsychiatric disorder in childhood and is characterized by a delay of cortical maturation in frontal regions. In order to investigate interference control, which is a key function of frontal areas, a functional MRI study was conducted on 17 ADHD boys and 17 typically developing (TD) boys, while solving the multi source interference task (MSIT). This task consists of two conditions, a "congruent condition" and an "incongruent condition". The latter requires to inhibit information that interferes with task-relevant stimuli. Behavioral results showed that ADHD subjects committed more errors than TD children. In addition, TD children presented a larger MSIT effect -a greater difference in reaction times between the incongruent and the congruent conditions- than ADHD children. Associated to the MSIT effect, neuroimaging results showed a significant enhancement in the activation of the right lateral prefrontal cortex (rlPFC) in ADHD than in TD subjects. Finally, ADHD subjects presented greater functional connectivity between rlPFC and bilateral orbitofrontal cortex than the TD group. This difference in connectivity correlated with worse performance in both groups. Our results could reflect a compensatory strategy of ADHD children resulting from their effort to maintain an adequate performance during MSIT.

[Heritability and genetic comorbidity of attention deficit disorder with hyperactivity]. / Déficit atencional con hiperactividad: trastorno multicausal de la conducta, con heredabilidad y comorbilidad genética moderadas.

This review aims to summarize information about the genetic etiology of attention deficit disorder with hyperactivity (ADHD), with particular reference to the contributions of our research group. We also discuss the genetic comorbidity estimated from genome-wide single nucleotide polymorphisms (SNP´s) between ADHD and major psychiatric disorders such as schizophrenia (E), major depressive disorder (MDD), bipolar disorder (BD) and autism spectrum disorders (ASD). A high genetic comorbidity was found between E and BD (46%), a moderate comorbidity between MDD and E, MDD and BD and MDD and ADHD (18%, 22% and 10% respectively) and a low comorbidity between E and ASD (2.5%). Furthermore, we show evidence concerning the genetic determination of psychiatric diseases, which is significantly lower when it is estimated from genome-wide SNP´s rather than using traditional quantitative genetic methodology (ADHD = E = 23%, BD = 25%, MDD = 21% and ASD = 17%). From an evolutionary perspective, we suggest that behavioral traits such as hyperactivity, inattention and impulsivity, which play a role in ADHD and perhaps also other hereditary traits which are part of major psychiatric disorders, could have had a high adaptive value during the early stages of the evolution of Homo sapiens. However, they became progressively less adaptive and definitively disadvantageous, to the extreme that they are involved in frequently diagnosed major psychiatric disorders.

Déficit atencional con hiperactividad: trastorno multicausal de la conducta, con heredabilidad y comorbilidad genética moderadas / Heritability and genetic comorbidity of attention deficit disorder with hyperactivity

This review aims to summarize information about the genetic etiology of attention deficit disorder with hyperactivity (ADHD), with particular reference to the contributions of our research group. We also discuss the genetic comorbidity estimated from genome-wide single nucleotide polymorphisms (SNP´s) between ADHD and major psychiatric disorders such as schizophrenia (E), major depressive disorder (MDD), bipolar disorder (BD) and autism spectrum disorders (ASD). A high genetic comorbidity was found between E and BD (46%), a moderate comorbidity between MDD and E, MDD and BD and MDD and ADHD (18%, 22% and 10% respectively) and a low comorbidity between E and ASD (2.5%). Furthermore, we show evidence concerning the genetic determination of psychiatric diseases, which is significantly lower when it is estimated from genome-wide SNP´s rather than using traditional quantitative genetic methodology (ADHD = E = 23%, BD = 25%, MDD = 21% and ASD = 17%). From an evolutionary perspective, we suggest that behavioral traits such as hyperactivity, inattention and impulsivity, which play a role in ADHD and perhaps also other hereditary traits which are part of major psychiatric disorders, could have had a high adaptive value during the early stages of the evolution of Homo sapiens. However, they became progressively less adaptive and definitively disadvantageous, to the extreme that they are involved in frequently diagnosed major psychiatric disorders.

Irrelevant stimulus processing in ADHD: catecholamine dynamics and attentional networks.

A cardinal symptom of attention deficit and hyperactivity disorder (ADHD) is a general distractibility where children and adults shift their attentional focus to stimuli that are irrelevant to the ongoing behavior. This has been attributed to a deficit in dopaminergic signaling in cortico-striatal networks that regulate goal-directed behavior. Furthermore, recent imaging evidence points to an impairment of large scale, antagonistic brain networks that normally contribute to attentional engagement and disengagement, such as the task-positive networks and the default mode network (DMN). Related networks are the ventral attentional network (VAN) involved in attentional shifting, and the salience network (SN) related to task expectancy. Here we discuss the tonic-phasic dynamics of catecholaminergic signaling in the brain, and attempt to provide a link between this and the activities of the large-scale cortical networks that regulate behavior. More specifically, we propose that a disbalance of tonic catecholamine levels during task performance produces an emphasis of phasic signaling and increased excitability of the VAN, yielding distractibility symptoms. Likewise, immaturity of the SN may relate to abnormal tonic signaling and an incapacity to build up a proper executive system during task performance. We discuss different lines of evidence including pharmacology, brain imaging and electrophysiology, that are consistent with our proposal. Finally, restoring the pharmacodynamics of catecholaminergic signaling seems crucial to alleviate ADHD symptoms; however, the possibility is open to explore cognitive rehabilitation strategies to top-down modulate network dynamics compensating the pharmacological deficits.

Temporal constraints of behavioral inhibition: relevance of inter-stimulus interval in a Go-Nogo task.

The capacity to inhibit prepotent and automatic responses is crucial for proper cognitive and social development, and inhibitory impairments have been considered to be key for some neuropsychiatric conditions. One of the most used paradigms to analyze inhibitory processes is the Go-Nogo task (GNG). This task has been widely used in psychophysical and cognitive EEG studies, and more recently in paradigms using fMRI. However, a technical limitation is that the time resolution of fMRI is poorer than that of the EEG technique. In order to compensate for these temporal constraints, it has become common practice in the fMRI field to use longer inter-stimulus intervals (ISI) than those used in EEG protocols. Despite the noticeable temporal differences between these two techniques, it is currently assumed that both approaches assess similar inhibitory processes. We performed an EEG study using a GNG task with both short ISI (fast-condition, FC, as in EEG protocols) and long ISI (slow-condition, SC, as in fMRI protocols). We found that in the FC there was a stronger Nogo-N2 effect than in the SC. Moreover, in the FC, but not in the SC, the number of preceding Go trials correlated positively with the Nogo-P3 amplitude and with the Go trial reaction time; and negatively with commission errors. In addition, we found significant topographical differences for the Go-P3 elicited in FC and SC, which is interpreted in terms of different neurotransmitter dynamics. Taken together, our results provide evidence that frequency of stimulus presentation in the GNG task strongly modulates the behavioral response and the evoked EEG activity. Therefore, it is likely that short-ISI EEG protocols and long-ISI fMRI protocols do not assess equivalent inhibitory processes.

Exogenous orienting of visual-spatial attention in ADHD children.

Visual spatial orienting of attention towards exogenous cues has been one of the attentional functions considered to be spared in ADHD. Here we present a design in which 60 (30 ADHD) children, age: 10.9±1.4, were asked to covertly orient their attention to one or two (out of four) cued locations, and search for a target stimulus in one of these locations, while recording behavioral responses and EEG/ERP. In all conditions, ADHD children showed delayed reaction times and poorer behavioral performance. They also exhibited larger cue-elicited P2 but reduced CNV in the preparation stage. Larger amplitude of CNV predicted better performance in the task. Target-elicited N1 and selection negativity were also reduced in the ADHD group compared to non-ADHD. Groups also differed in the early and late P3 time-windows. The present results suggest that exogenous orienting of attention could be dysfunctional in ADHD under certain conditions. This limitation is not necessarily caused by an impairment of the orienting process itself, but instead by a difficulty in maintaining the relevant information acquired during the early preparation stage through the target processing stage, when it is really needed.

Trastorno por déficit de atención e hiperactividad en niños aymara: primera aproximación clínica / Attention deficit hyperactivity disorder in Aymara children

Background: The assessment of Attentional Deficit Hyperactivity Disorder (ADHD) among ethnic groups may reveal environmental or cultural variables that influence the appearance of this disorder. Aim: To assess the presence and characteristics of ADHD in two communities of the inland Arica valleys (Azapa and Lluta), where the Aymara population predominates. Material and Methods: Startingfrom a screening based on the Conner's test, we evaluated 79 children aged 8 to 13 years. Sixty children were of Aymara origin and 19 children were of non-Aymara origin. Twenty Aymara and 9 non-Aymara children had ADHD. They were compared with a group of patients from Santiago, Chile (110 children) that were previously assessed. Results: Patientsfrom Azapa/Lluta displayed similar characteristics to those from Santiago. However the former had significantly less psychiatric comorbidities than the latter. On the other hand, the non-Aymara subgroup of Azapa/ Lluta displayed an increased rate of comorbidities and was exclusively of the combined subtype, although their sample size is too small to draw strong conclusions. Conclusions: Although we cannot dismiss biological variables, the importance of family values and the respect to authorities may be protective factors for ADHD, associated to Aymara culture. Our findings suggest that the clinical characteristics of ADHD are not uniform among ethnic groups and cultures. The relative contribution of environmental and genetic factors in this variability remain to be determined.

[Attention deficit hyperactivity disorder in Aymara children]. / Trastorno por déficit de atención e hiperactividad en niños aymara: primera aproximación clínica.

BACKGROUND: The assessment of Attentional Deficit Hyperactivity Disorder (ADHD) among ethnic groups may reveal environmental or cultural variables that influence the appearance of this disorder. AIM: To assess the presence and characteristics of ADHD in two communities of the inland Arica valleys (Azapa and Lluta), where the Aymara population predominates. MATERIAL AND METHODS: Starting from a screening based on the Conner's test, we evaluated 79 children aged 8 to 13 years. Sixty children were of Aymara origin and 19 children were of non-Aymara origin. Twenty Aymara and 9 non-Aymara children had ADHD. They were compared with a group of patients from Santiago, Chile (110 children) that were previously assessed. RESULTS: Patients from Azapa/Lluta displayed similar characteristics to those from Santiago. However the former had significantly less psychiatric comorbidities than the latter. On the other hand, the non-Aymara subgroup of Azapa/Lluta displayed an increased rate of comorbidities and was exclusively of the combined subtype, although their sample size is too small to draw strong conclusions. CONCLUSIONS: Although we cannot dismiss biological variables, the importance of family values and the respect to authorities may be protective factors for ADHD, associated to Aymara culture. Our findings suggest that the clinical characteristics of ADHD are not uniform among ethnic groups and cultures. The relative contribution of environmental and genetic factors in this variability remain to be determined.

[Risk of attention deficit/hyperactivity disorder in Aymara and Rapa-Nui school children: association with dopaminergic system polymorphisms]. / Riesgo de déficit atencional/hiperactividad en escolares Aymara, Rapa-Nui y de Santiago de Chile: Posible contribución de polimorfismos genéticos del sistema dopaminérgico.

BACKGROUND: Attention deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurobiological disorder of childhood onset, characterized by hyperactivity, impulsiveness or inattentiveness. AIM: To search for differences in risk for ADHD and its components among Chilean native and mixed populations and to look forpossible associations with dopamine receptor D4 (DRD4) and dopamine transporter 1 (DAT1) polymorphisms. MATERIAL AND METHODS: School teachers were requested to complete the Conners test, which uses DSM-IV criteria, to screen for ADHD risk among Aymara and Rapa-Nui students. RESULTS: Rapa-Nui children from Easter Island had the highest risk of hyperactivity/impulsiveness. Aymara children from the Arica-Parinacota Region had lower scores. Although inattentiveness scores had lower differences between groups, overall ADHD score differences among studied populations were highly significant. DRD4 and DAT1 alleles had a heterogeneous distribution. Easter islanders had more divergent frequencies, mostprobably as a result of separate migration routes utilized at different timeperiods during the colonization of America and Polynesia. CONCLUSIONS: The comparison of ADHD risk parameters between Rapa-Nui and Aymara children showed marked differences. Allele distri-bution of dopamine polymorphisms in Easter Island was also significantly different from northern Chile, due probably to different colonization histories. These findings suggest that higher ADHD risk scores in Easter Island children may be linked to the presence of different DRD4 alleles.

Riesgo de déficit atencional/hiperactividad en escolares Aymara, Rapa-Nui y de Santiago de Chile: Posible contribución de polimorfismos genéticos del sistema dopaminérgico / Risk of attention deficit/hyperactivity disorder in Aymara and Rapa-Nui school children: Association with dopaminergic system polymorphisms

Background: Attention deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurobiological disorder of childhood onset, characterized by hyperactivity, impulsiveness or inattentiveness. Aim: To search for differences in risk for ADHD and its components among Chilean native and mixed populations and to look forpossible associations with dopamine receptor D4 (DRD4) and dopamine transporter 1 (DAT1) polymorphisms. Material and Methods: School teachers were requested to complete the Conners test, which uses DSM-IV criteria, to screen for ADHD risk among Aymara and Rapa-Nui students. Results: Rapa-Nui children from Easter Island had the highest risk of hyperactivity/impulsiveness. Aymara children from the Arica-Parinacota Region had lower scores. Although inattentiveness scores had lower differences between groups, overall ADHD score differences among studied populations were highly significant. DRD4 and DAT1 alleles had a heterogeneous distribution. Easter islanders had more divergent frequencies, mostprobably as a result of separate migration routes utilized at different timeperiods during the colonization of America and Polynesia. Conclusions: The comparison of ADHD risk parameters between Rapa-Nui and Aymara children showed marked differences. Allele distri-bution of dopamine polymorphisms in Easter Island was also significantly different from northern Chile, due probably to different colonization histories. These findings suggest that higher ADHD risk scores in Easter Island children may be linked to the presence of different DRD4 alleles.

Plasticity in primary somatosensory cortex resulting from environmentally enriched stimulation and sensory discrimination training

We studied primary-somatosensory cortical plasticity due to selective stimulation of the sensory periphery by two procedures of active exploration in adult rats. Subjects, left with only three adjacent whiskers, were trained in a roughness discrimination task or maintained in a tactile enriched environment. Either training or enrichment produced 3-fold increases in the barrel cortex areas of behaviorally-engaged whisker representations, in their zones of overlap. While the overall areas of representation expanded dramatically, the domains of exclusive principal whisker responses were virtually identical in enriched vs normal rats and were significantly smaller than either group in roughness discrimination-trained rats. When animals were trained or exposed to enriched environments with the three whiskers arrayed in an are or row, very equivalent overlaps in representations were recorded across their greatly-enlarged whisker representation zones. This equivalence in distortion in these behavioral preparations is in contradistinction to the normal rat, where overlap is strongly biased only along rows, probably reflecting the establishment of different relations with the neighboring cortical columns. Overall, plasticity phenomena are argued to be consistent with the predictions of competitive Hebbian network plasticity.

Non-homogeneous spatial configuration of vibrissae cortical representation in layer IV of the barrel somatosensory cortex

In the present experiments we studied exclusive and overlapping cortical representational areas of the vibrissae in layer IV cells, across the entire barrel subfield of the rat somatosensory cortex, looking for evidences that would challenge the present assumptions of homogeneity and symmetry among cortical columns in this sensorial system. Our main findings were that in layer IV of the rat barrel cortex: A) Size of vibrissae cortical representational areas (X=0.4174mm²; SD=0.025) was not homo geneous, vibrissae in dorsal rows (A-B) had significantly smaller areas than those in ventral rows (D-E), a pattern that repeated itself in arcs 1-4. B) This difference arises from vibrissal representational overlap, and not from variations in exclusive zones, which are surprisingly homogeneous in size across the barrel cortex (X=0.079mm²; SD=0.0075); C) The extent of overlapping cortical areas varied systematically, with intra-row overlapping areas having a predominant bias (71.4 percent of total overlapping) independent of area sizes. Accordingly, vibrissae shared receptive fields with an average of 1.15 vibrissae in the same row and 0.38 in the same are. Barrel cortex has been viewed operationally as a conglomerate of essentially homogenous cortical columns that interact equivalently in the are and row dimensions. Our simple but global cortical reconstructions show that this predominant view should be revised. We postulate that the vibrissae/barrels spatial disposition in rows and ares has a relevant functional meaning, related to different sensory capabilities.