Distraction by deviant sounds is modulated by the environmental context.

Evidence shows that participants performing a continuous visual categorization task respond slower following the presentation of a task-irrelevant sound deviating from an otherwise repetitive or predictable auditory context (deviant sound among standard sounds). Here, for the first time, we explored the role of the environmental context (instrumentalized as a task-irrelevant background picture) in this effect. In two experiments, participants categorized left/right arrows while ignoring irrelevant sounds and background pictures of forest and city scenes. While equiprobable across the task, sounds A and B were presented with probabilities of .882 and .118 in the forest context, respectively, and with the reversed probabilities in the city context. Hence, neither sound constituted a deviant sound at task-level, but each did within a specific context. In Experiment 1, where each environmental context (forest and city scene) consisted of a single picture each, participants were significantly slower in the visual task following the presentation of the sound that was unexpected within the current context (context-dependent distraction). Further analysis showed that the cognitive system reset its sensory predictions even for the first trial of a change in environmental context. In Experiment 2, the two contexts (forest and city) were implemented using sets of 32 pictures each, with the background picture changing on every trial. Here too, context-dependent deviance distraction was observed. However, participants took a trial to fully reset their sensory predictions upon a change in context. We conclude that irrelevant sounds are incidentally processed in association with the environmental context (even though these stimuli belong to different sensory modalities) and that sensory predictions are context-dependent.

Distraction by violation of sensory predictions: Functional distinction between deviant sounds and unexpected silences.

It has been established that participants performing a continuous categorization task respond significantly slower following the presentation of unexpected, task-irrelevant, auditory stimuli, compared to a repetitive (standard) sound. Evidence indicates that such distraction emerges because of the violation of sensory predictions. This has typically been studied by measuring the impact of replacing the repeated sound by a different sound on rare and unpredictable trials. Here, we examine the impact of a different type of violation: the mere omission of the standard sound. Capitalizing upon the recent finding that deviant sounds exert distinct effects on response times as a function of whether participants produced or withheld a response on the previous trial, we present the results of an experiment seeking to disentangle two potential effects of sound omission: deviance distraction and the removal of an unspecific warning signal. The results indicate that deviant sound and the unexpected omission of the standard sound impact response times through, at least partially, distinct mechanisms. Deviant sounds affect performance by triggering the orienting of attention towards a new sensory input. Sound omissions, in contrast, appear to affect performance in part because responses no longer benefit from an unspecific warning signal to prepare for action.

Cognitive control modulates the expression of implicit sequence learning: Congruency sequence and oddball-dependent sequence effects.

Implicit sequence learning represents an established paradigm to investigate incidental skill acquisition in a laboratory environment. During a covert task, participants respond to the location of a target appearing over a series of locations according to a complex sequence, which gets violated in a reduced set of control trials. Even though participants are not fully aware of the sequence, they respond faster and more accurately to trials following it, thus expressing sequence knowledge. Recent evidence has challenged the view that such knowledge is applied rigidly and affects performance independently from control influences. Jiménez et al. (2009) highlighted that its expression gets reduced immediately after trials not conforming with the learned sequence-an effect that resembles the congruency sequence effect (CSE) commonly observed in interference tasks. However, such effects can also be alternatively explained in associative terms. In this experimental series we took advantage of the well-known attentional properties of oddball sounds and introduced them as an orthogonal variable with respect to the learning process. We found that oddball sounds also hindered the automatic expression of sequence learning, highlighting an oddball-dependent sequence effect similar to the CSE, but most clearly triggered by cognitive control. Moreover, as illustrated through a simulation with a simple recurrent network (SRN), we showed that the CSE reported in this article under noisier conditions is harder to expect from associative processes. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Aging Increases Cross-Modal Distraction by Unexpected Sounds: Controlling for Response Speed.

It is well-established that task-irrelevant sounds deviating from an otherwise predictable auditory sequence capture attention and disrupt ongoing performance by delaying responses in the ongoing task. In visual tasks, larger distraction by unexpected sounds (deviance distraction) has been reported in older than in young adults. However, past studies based this conclusion on the comparisons of absolute response times (RT) and did not control for the general slowing typically observed in older adults. Hence, it remains unclear whether this difference in deviance distraction between the two age groups reflects a genuine effect of aging or a proportional effect of similar size in both groups. We addressed this issue by using a proportional measure of distraction (PMD) to reanalyze the data from four past studies and used Bayesian estimation to generate credible estimates of the age-related difference in deviance distraction and its effect size. The results were unambiguous: older adults exhibited greater deviance distraction than young adults when controlling for baseline response speed (in each individual study and in the combined data set). Bayesian estimation revealed a proportional lengthening of RT by unexpected sounds that was about twice as large in older than in young adults (corresponding to a large statistical effect size). A similar analysis was carried out on the proportion of correct responses (PC) and produced converging results. Finally, an additional Bayesian analysis comparing data from cross-modal and uni-modal studies confirmed the selective effect of aging on distraction in the first and not the second. Overall, our study shows that older adults performing a visual categorization task do exhibit greater distraction by unexpected sounds than young adults and that this effect is not explicable by age-related general slowing.

The causal role of DLPFC top-down control on the acquisition and the automatic expression of implicit learning: State of the art.

Implicit learning refers to the incidental acquisition and expression of knowledge that is not accompanied by full awareness of its contents. Implicit sequence learning (ISL) represents one of the most useful paradigms to investigate these processes. In this paradigm, participants are usually instructed to respond to the location of a target that moves regularly through a set of possible locations. Although participants are not informed about the existence of a sequence, they eventually learn it implicitly, as attested by the costs observed when this sequence is violated in a reduced set of control trials. Interestingly, the expression of this learning decreases immediately after a control trial, in a way that resembles the adjustments triggered in response to incongruent trials in interference tasks. These effects have been attributed to a control network involving dorsolateral prefrontal cortex (DLPFC) and cingulate (ACC) structures. In the present work, we reviewed a group of recent studies which had inhibited DLPFC top-down control by means of non-invasive brain stimulation to increase the acquisition of ISL. In addition, as no previous study has investigated the effect of inhibiting top-down control on releasing the automatic expression of ISL, we present a pre-registered - yet exploratory - study in which an inhibitory continuous theta burst stimulation protocol was applied over an anterior-ventral portion of the dorsolateral prefrontal cortex (DLPFC) highly interconnected with the ACC, and whose activity has been specifically linked to motor control (i.e., Right DLPFC, n = 10 or the Left DLPFC, n = 10), compared to active Vertex stimulation (n = 10). Contrary to our hypotheses, the results did not show evidence for the involvement of such region in the expression of ISL. We discussed the results in the context of the set of contradictory findings reported in the systematic review.

Distraction by deviant sounds: disgusting and neutral words capture attention to the same extent.

Several studies have argued that words evoking negative emotions, such as disgust, grab attention more than neutral words, and leave traces in memory that are more persistent. However, these conclusions are typically based on tasks requiring participants to process the semantic content of these words in a voluntarily manner. We sought to compare the involuntary attention grabbing power of disgusting and neutral words using them as rare and unexpected auditory distractors in a cross-modal oddball task, and then probing the participants' memory for these stimuli in a surprise recognition task. Frequentist and Bayesian analyses converged to show that, compared to a standard tone, disgusting and neutral auditory words produced significant but equivalent levels of distraction in a visual categorization task, that they elicited comparable levels of memory discriminability in the incidental recognition task, and that the participants' individual sensitivity to disgust did not influence the results. Our results suggest that distraction by unexpected words is not modulated by their emotional valence, at least when these words are task-irrelevant and are temporally and perceptually decoupled from the target stimuli.

Continuation versus discontinuation of treatment for severe dementia: randomized, pragmatic, open-label, clinical trial to evaluate the efficacy of continuing drug treatment in patients with severe dementia (STOP-DEM).

BACKGROUND: Previous observational studies and clinical trials have shown that cholinesterase inhibitors (with or without memantine) provide benefit for patients with mild-to-moderate Alzheimer's disease. However, the impact of treatment continuation after progression to severe disease is unknown. The main aim of this study is to evaluate the effect and safety of continuing treatment with ChEIs (with or without memantine) for patients with severe dementia. METHODS: This randomized, pragmatic, open-label clinical trial with blinded evaluators will evaluate the efficacy of continuing drug treatment in patients with advanced dementia. A total of 302 community-dwelling patients with severe dementia, Alzheimer's disease, with or without a coexisting diagnosis of vascular dementia, and a score of 10 or less on the Mini-Mental State Examination who received previous treatment with a cholinesterase inhibitor (with or without memantine) for at least 3 months, will be randomized to continue or discontinue drug treatment. Follow-up will be 12 months or until the primary endpoint is achieved. The primary endpoint is entry into institutional care and progression of disability, defined as a loss of 2 of 4 basic functions, or 6 of 11 instrumental functions, according to the Bristol Activities of Daily Living Scale at 12 months. The secondary outcomes are patient changes in functional and cognitive state, quality of life, and caregiver burden. DISCUSSION: We expect that the results of our study will allow to identify if there is clinical relevant impact for patients and caregivers between maintaining or halting pharmacological treatment. TRIAL REGISTRATION: The study was prospectively registered in the REec (2017-000042-22) on May 11 2017 and ID ISRCTN12134230 on February 25 2019.

The role of age, working memory, and response inhibition in deviance distraction: A cross-sectional study.

Sounds deviating from an otherwise repeated or structured sequence capture attention and affect performance in an ongoing visual task negatively, testament to the balance between selective attention and change detection. Although deviance distraction has been the object of much research, its modulation across the life span has been more scarcely addressed. Recent findings suggest possible connections with working memory and response inhibition. In this study we measured the performance of children and young and older adults in a cross-modal oddball task (deviance distraction), a working memory task (working memory capacity), and a response inhibition task (ability to voluntarily inhibit an already planned action) with the aim to establish the contribution of the latter 2 to the first. Older adults exhibited significantly more deviance distraction than children and young adults (who did not differ from each other). Working memory capacity mediated deviance distraction in children and older adults (though in opposite directions) but not in young adults. Response inhibition capacities did not mediate deviance distraction in any of the age groups. Altogether the results suggest that although the increase in deviance distraction observed in old age may partly reflect the relative impairment of working memory mechanisms, there is no straightforward and stable relation between working memory capacity and deviance distraction across the life span. Furthermore, our results indicate that deviance distraction is unlikely to reflect the temporary inhibition of responses. (PsycINFO Database Record

Reorienting the mind: The impact of novel sounds on go/no-go performance.

The present study explores the link between attentional reorienting and response inhibition. Recent behavioral and neuroscience work indicates that both might rely on similar cognitive and neural mechanisms. We tested 2 popular accounts of the overlap: The "circuit breaker" account, which assumes that unexpected events produce global suppression of motor output, and the "stimulus detection" account, which assumes that attention is reoriented to unexpected events. In Experiment 1, we presented standard and (unexpected) novel sounds in a go/no-go task. Consistent with the stimulus detection account, we found longer reaction times on go trials and higher rates of commission errors on no-go trials when these were preceded by a novel sound compared with a standard sound. In Experiment 2, novel and standard sounds acted as no-go signals. In this experiment, the novel sounds produced an improvement on no-go trials. This further highlights the importance of stimulus detection for response inhibition. Combined, the 2 experiments support the idea that attention is oriented to novel or unexpected events, impairing no-go performance if these events are irrelevant but enhancing no-go performance when they are relevant. Our findings also indicate that the popular circuit breaker account of the overlap between response inhibition and attentional reorienting needs some revision.

When aging does not increase distraction: Evidence from pure auditory and visual oddball tasks.

Past research indicates that age increases deviance distraction in cross-modal oddball tasks, but results are few and less conclusive in purely auditory oddball tasks, with 3 studies not reporting age-related increase in deviance distraction against 1 that did (d = 1.04). This study aimed to (a) examine the effect of age on deviance distraction using the largest sample size to date to ensure adequate statistical power and (b) extend the study of same-modality deviance distraction to the visual modality. We compared 42 young and 42 older adults in auditory and visual duration discrimination tasks in which stimuli were presented with rare and unexpected task-irrelevant changes in pitch (in the auditory task) or location (in the visual task). The statistical power of our experiment to detect an effect size (d) of 1.04 was .999. Our results showed deviance distraction (longer response times for deviant stimuli than for standard stimuli) in both modalities. Importantly, these effects did not vary with age. Strong support for the absence of age-related variation in deviance distraction was further demonstrated by Bayes factor analysis. We conclude that aging does not appear to increase behavioral distraction by deviant stimuli in same-modality oddball tasks.

Distraction by deviance: comparing the effects of auditory and visual deviant stimuli on auditory and visual target processing.

We report the results of oddball experiments in which an irrelevant stimulus (standard, deviant) was presented before a target stimulus and the modality of these stimuli was manipulated orthogonally (visual/auditory). Experiment 1 showed that auditory deviants yielded distraction irrespective of the target's modality while visual deviants did not impact on performance. When participants were forced to attend the distractors in order to detect a rare target ("target-distractor"), auditory deviants yielded distraction irrespective of the target's modality and visual deviants yielded a small distraction effect when targets were auditory (Experiments 2 & 3). Visual deviants only produced distraction for visual targets when deviant stimuli were not visually distinct from the other distractors (Experiment 4). Our results indicate that while auditory deviants yield distraction irrespective of the targets' modality, visual deviants only do so when attended and under selective conditions, at least when irrelevant and target stimuli are temporally and perceptually decoupled.

Aging increases distraction by auditory oddballs in visual, but not auditory tasks.

Aging is typically considered to bring a reduction of the ability to resist distraction by task-irrelevant stimuli. Yet recent work suggests that this conclusion must be qualified and that the effect of aging is mitigated by whether irrelevant and target stimuli emanate from the same modalities or from distinct ones. Some studies suggest that aging is especially sensitive to distraction within-modality while others suggest it is greater across modalities. Here we report the first study to measure the effect of aging on deviance distraction in cross-modal (auditory-visual) and uni-modal (auditory-auditory) oddball tasks. Young and older adults were asked to judge the parity of target digits (auditory or visual in distinct blocks of trials), each preceded by a task-irrelevant sound (the same tone on most trials-the standard sound-or, on rare and unpredictable trials, a burst of white noise-the deviant sound). Deviant sounds yielded distraction (longer response times relative to standard sounds) in both tasks and age groups. However, an age-related increase in distraction was observed in the cross-modal task and not in the uni-modal task. We argue that aging might affect processes involved in the switching of attention across modalities and speculate that this may due to the slowing of this type of attentional shift or a reduction in cognitive control required to re-orient attention toward the target's modality.

The informational constraints of behavioral distraction by unexpected sounds: the role of event information.

Sounds deviating from an otherwise repeated stream of task-irrelevant auditory stimuli (deviant sounds among standard sounds) are known to capture attention and impact negatively on ongoing behavioral performance (behavioral oddball distraction). Traditional views consider such distraction as the ineluctable consequence of the deviant sounds' low probability of occurrence relative to that of the standard. Contrary to this contention, recent evidence demonstrates that distraction by deviant sounds is not obligatory and occurs only when sounds (standards and deviants), though to be ignored, act as useful warning cues by providing information as to whether and when a target stimulus is to be presented (Parmentier, Elsley, & Ljungberg, 2010). The present study aimed to extend this finding by disentangling the roles of event information (target's probability of occurrence) and temporal information (target's time of occurrence). Comparing performance in a cross-modal oddball task where standard and deviant sounds provided temporal information, event information, both, or none, we found that distraction by deviant sounds emerged when sounds conveyed event information. These results suggest that unexpected changes in a stream of sounds yield behavioral distraction to the extent that standards and deviants carry relevant goal-directed information, specifically, the likelihood of occurrence of an upcoming target.

Ansiedad competitiva y clima motivacional en jóvenes futbolistas de competición, en relación con las habilidades y el rendimiento percibido por sus entrenadores / Performance anxiety and motivational climate in young competitive soccer players in relation to performance and skills perceived by their coaches

En este estudio se analizan las relaciones existentes entre la ansiedad competitiva (en sus facetas cognitiva y somática) y el clima motivacional percibido (de ego y de maestría) en una población de 54 jóvenes futbolistas de competición de edad media de 9,45 años, respecto de la percepción de sus habilidades y rendimiento deportivos por parte de sus 4 entrenadores, que también participaron en el estudio. Para ello se les administró las versiones españolas del SAS-2 (Sport Anxiety Scale-2, Smith, Smoll, Cumming y Grossbard, 2006) y el MCSYS (Motivational Climate Scale for Youth Sports, Smith, Cumming y Smoll, 2008), así como dos escalas ad hoc para evaluar la percepción de su habilidad y rendimiento. Los resultados muestran, por una parte, que los jóvenes futbolistas perciben y discriminan claramente los climas motivacionales, que se distribuyen casi al 50% entre ego y maestría; por otra, que aparece ansiedad competitiva, aunque más cognitiva que somática, y que no existe relación significativa con las percepciones de habilidad y rendimiento por parte de los entrenadores. Finalmente, estos resultados se discuten y se comparan con otros similares en poblaciones preadolescentes (AU)

This study analysed the relationships between competitive anxiety (both cognitive and somatic) and perceived motivational climate (ego and mastery) in 54 young competitive soccer players (mean age: 9.45 years), related to their four coaches’ perceptions of the soccer players’ skills and performance. We administered the Spanish versions of the SAS-2 (Sport Anxiety Scale-2, Smith, Smoll, Cumming and Grossbard, 2006) and the MCSYS (Motivational Climate Scale for Youth Sports, Smith, Cumming and Smoll, 2008), along with two ad hoc scales to evaluate perceived skills and performance. The results show that 1) young players perceived and discriminated clearly between motivational climates (which were more or less equally distributed between ego and mastery orientations), 2) some performance-related anxiety (mostly cognitive rather than somatic) appeared and 3) no significant relationships were found between their coaches’ perceptions of their skills and their performance. Lastly, the results are discussed and compared with similar results from preadolescent players (AU)

[Reference values for inspiratory capacity in healthy nonsmokers over age 50 years]. / Valores de referencia de la capacidad inspiratoria en sujetos sanos no fumadores mayores de 50 años.

OBJECTIVE: The role of dynamic hyperinflation in triggering dyspnea and limiting exercise capacity in patients with chronic obstructive pulmonary disease has been recognized in recent years. The degree of dynamic hyperinflation can be assessed by measuring reduction in inspiratory capacity (IC). The aim of this study was to establish reference values for IC in healthy individuals of both sexes between the ages of 50 and 87 years, as such data are scarce in the literature. SUBJECTS AND METHODS: We studied 155 healthy volunteers (93 women) with normal spirometry. None had a prior history of respiratory, cardiovascular, or systemic diseases that might alter lung function. All were never-smokers. IC was measured during a normal, unforced inspiration to total lung capacity starting from functional residual capacity. The highest value of 6 satisfactory maneuvers was recorded. Sex, height, age, and weight were included in the regression equations. One thousand bootstrap samples for each sex were also analyzed. RESULTS: For each sex, we found that a model including age, height, and weight produced IC prediction equations with a coefficient of determination (r2) of 0.414 for women and 0.447 for men. The mean (SD) intrasubject coefficient of variation was 4.3% (2%) for IC measured during a single session and 5.1% (0.4%) for measurements from 5 weekly sessions. CONCLUSIONS: Our results provide reference equations for IC that are valid for a healthy population over 50 years of age. Predicted values were similar to those recently obtained in an Italian population aged between 65 and 85 years.

Valores de referencia de la capacidad inspiratoria en sujetos sanos no fumadores mayores de 50 años / Reference values for inspiratory capacity in healthy nonsmokers over age 50 years

Objetivo: En los últimos años se ha reconocido la importancia de la hiperinflación dinámica en la génesis de la disnea y de la limitación al ejercicio en la enfermedad pulmonar obstructiva crónica (EPOC), y que su magnitud puede evaluarse a través de la reducción de la capacidad inspiratoria (CI). Nuestro objetivo ha sido establecer valores de referencia de la CI en individuos sanos de ambos sexos, de entre 50 y 87 años de edad, debido a que en la literatura médica disponible prácticamente no se ofrecen tales datos. Sujetos y métodos: Estudiamos a 155 voluntarios sanos (93 mujeres), que nunca habían fumado ni presentaban antecedentes de enfermedades respiratorias, cardiovasculares o sistémicas que pudieran alterar la función pulmonar, y cuya espirometría era normal. La CI se midió durante una inspiración no forzada hasta la capacidad pulmonar total a partir del valor en reposo espiratorio, y para los resultados se empleó el valor más alto de 6 maniobras satisfactorias. En las ecuaciones de regresión se incluyeron el sexo, la talla, la edad y el peso. Se empleó además el método de bootstrapping de 1.000 muestras para cada sexo como procedimiento de análisis. Resultados: Encontramos para cada sexo que un mode-lo que incorporó la edad, la talla y el peso produjo ecuaciones predictivas de CI con un coeficiente de determinación r2 = 0,414 y 0,447 para mujeres y varones, respectivamente. El coeficiente de variación intrasujeto en una misma sesión fue (media ± desviación estándar) del 4,3 ± 2%, y en 5 sesiones separadas por una semana fue del 5,1 ± 0,4%. Conclusiones: Nuestros resultados proporcionan ecuaciones de referencia para CI válidas en población sana mayor de 50 años. Los valores predichos son semejantes a los recientemente obtenidos en población italiana de 65-85 años de edad

Objective: The role of dynamic hyperinflation in triggering dyspnea and limiting exercise capacity in patients with chronic obstructive pulmonary disease has been recognized in recent years. The degree of dynamic hyperinflation can be assessed by measuring reduction in inspiratory capacity (IC). The aim of this study was to establish reference values for IC in healthy individuals of both sexes between the ages of 50 and 87 years, as such data are scarce in the literature. Subjects and Methods: We studied 155 healthy volunteers (93 women) with normal spirometry. None had a prior history of respiratory, cardiovascular, or systemic diseases that might alter lung function. All were never-smokers. IC was measured during a normal, unforced inspiration to total lung capacity starting from functional residual capacity. The highest value of 6 satisfactory maneuvers was recorded. Sex, height, age, and weight were included in the regression equations. One thousand bootstrap samples for each sex were also analyzed. Results: For each sex, we found that a model including age, height, and weight produced IC prediction equations with a coefficient of determination (r2) of 0.414 for women and 0.447 for men. The mean (SD) intrasubject coefficient of variation was 4.3% (2%) for IC measured during a single session and 5.1% (0.4%) for measurements from 5 weekly sessions. Conclusions: Our results provide reference equations for IC that are valid for a healthy population over 50 years of age. Predicted values were similar to those recently obtained in an Italian population aged between 65 and 85 years

Adaptación de la prueba de caminata en 6 minutos en corredor a cinta rodante en pacientes con enfermedad pulmonar obstructiva crónica / Adaptation of six minute walk test in a hallway to a treadmill in patients with chronic obstructive pulmonary disease

El objetivo de este estudio fue evaluar si es posible reproducir la prueba de caminata en 6 minutos (C6M) realizada en un corredor con la obtenida en cinta rodante (CR) en pacientes con enfermedad pulmonar obstructiva crónica (EPOC). Se estudió 27 pacientes con EPOC estable, edad 68 ± 8 años y VEF1 54 ± 16 por ciento teórico (X ± DE). La C6M se realizó en un corredor registrándose distintas variables fisiológicas. Para la aplicación en la CR se consideró la velocidad promedio de tres pruebas de caminata en el corredor. La distancia recorrida fue semejante en ambas situaciones. El grado de disnea y la SpO2 al final de la prueba también fue similar en las doscondiciones. En cambio la FC y el grado de fatiga fueron significativamente mayores. Estos resultados demuestran que la prueba de C6M puede ser reproducida en la CR, permitiendo medir la respuesta ventilatoria durante la prueba.

Un índice del tamaño pulmonar mejora la predicción de valores de referencia de PC20 metacolina en un grupo de niños y adultos normales chilenos / A index of lung volume improves the prediction of reference values of methacholine PC20 in normal chilean children and adults

Con el propósito de examinar la validez del límite inferior de lo normal de 8 mg/ml para la PC20 metacolina en individuos normales chilenos, estudiamos 79 sujetos, 39 hombres y 40 mujeres, con edades entre 6 y 75 años. Se excluyeron los sujetos con condiciones capaces de alterar la respuesta a metacolina. En todos se efectuó una espirometría y una prueba de provocación con metacolina hasta llegar a concentraciones de 256 mg/ml, obtener un plateau o una caída del VEF, de 40 por ciento o más respecto del valor basal La PC20 se calculó por interpelación. También se efectuó un prick test con 9 alergenos comunes, clasificando como atópicos a aquellos que reaccionaron con uno o más alergenos. Se obtuvo PC20 en 35 individuos (44 por ciento), 11 de los cuales (13,9 por ciento) presentaron PC20 por debajo de 8 mg/ml. Hubo mayor prevalencia de PC20 en mujeres que en hombres (51,1 por ciento vs 31,6 por ciento, p < 0,05). No hubo diferencias de PC20 entre atópicos y no atópicos. Los individuos en los que se obtuvo PC20 fueron signifícativamente menores (25,6 ñ 18,8 vs 41,4 ñ 18,6 años, p < 0,01) y tuvieron menores valores absolutos de CVF (3.232 ñ 1.017 vs 4.038 ñ 1.245 ml, p <.0,025) y VEF, (2.793 ñ 920 vs 3.405 ñ 1.073 ml, p < 0,05). El log PC20 se correlacionó significativamente con CVF, VEF, y talla. En una correlación múltiple paso a paso sólo CVF entró al modelo de predicción de PC20. Los niños más pequeños e individuos mayores, con menores CVF, tuvieron PC20 más bajas. Concluimos que el límite inferior de lo normal de 8 mg/ml es inadecuado para los individuos con CVF pequeña, independientemente de la edad, por lo que una predicción de PC20 que considere este factor mejorará la sensibilidad y la especificidad en el diagnóstico de hiperreactividad bronquial

Curva dosis-respuesta a metacolina en niños normales hijos de asmáticos / Dose-response curves to methacholine in son of asthmatics normal children

Entre los parientes en primer grado de los enfermos conasma bronquial se ha demostrado una mayor prevalencia de esta enfermedad, la que crecería gradualmente hasta alcanzar cifras del orden de 43 por ciento a los 65 años. Con el propósito de establecer si los hijos de padres asmáticos(HPA) presentan alteraciones en la forma y posición de su curva dosis respuesta a metacolina, estudiamos 16 HPA y 16 controles sin antecedentes familiares de asma, escogidos por presentar edad (8,07 + - 0,45 años de edad, X + - ES)y hábito tabáquico familiar (3,8+ - 1,3 vs 2,9 + - 1,22 cigarrillos diarios)similares al grupo HPA. Ninguno de los niños presentaba enfermedades cardiorrespiratorias crónicas ni agudas durante los dos meses previos al estudio. Se efectuó una prueba de provocación administrando metacolina desde 0,03 hasta máxima (M), la posiciónde la curva a través de la dosis acumulativa que causa un 50 por ciento de M (ED50)y la PC20. No se observó diferencias significativas en M(39,8 promedio 3,89 vs 33,6 promedio 3,84 por ciento VEF1), enlogED50 (-1,29 + - 0,18 vs -1,22 + - 0,17mg)ni el logPC20(0,70 + - 0,22 vs 0,71 + - 0,22 mg/ml) al compararlas con su curva dosis-respuesta a metacolina respecto a niños sin antecedentes familiares de asma, lo que sugiere que la capacidad cantráctil de su músculo liso, las cargas que éste debe vencer y los factores que amplifican la respuesta de sus vías aéreas sonnormales en el estudio preasmático y que las alteraciones observadas en asmáticos serían adquiridas, probablemente por influencias ambientales