[Show abstract][Hide abstract] ABSTRACT: We conducted a longitudinal study of 30 preschool children with autism spectrum disorders (ASDs) to evaluate the potential benefits of the Treatment and Education of Autistic and related Communication Handicapped Children (TEACCH). Fifteen children following a low intensity TEACCH program were assessed four times for autism severity, adaptive functioning, language skills, maladaptive behaviors and parental stress and compared with a control group of 15 children following a non-specific approach. Findings suggest that a low intensity home and school TEACCH program may provide benefits for children with ASD by reducing autistic symptoms and maladaptive behaviors. Furthermore, a decrease in parental stress indicates that parents' involvement in the rehabilitation program is a crucial factor and contributes greatly to treatment efficacy.
Full-text · Article · Aug 2013 · Journal of Autism and Developmental Disorders
[Show abstract][Hide abstract] ABSTRACT: Background:
A variety of naturalistic interventions aim to account for an increasing adult’s responsiveness to the child and the quality of social engagement with the therapist and parent. Anyhow, social isolation is one of the most enduring challenges facing children with autism spectrum disorders (ASD), experiencing complex social difficulties in school. It is suggested that without direct naturalistic behavior intervention in the school setting, any naturalistic behavior intervention neither professional nor parent-mediated at home may be sufficient to fully engage children in peer activities and as such include them into a social structure.
This study examined collateral effects of staff-and parent-mediated naturalistic interventions without direct milieu teaching in the class room setting on peer interactions and play engagement.
The Playground Observation of Peer Engagement (POPE) has been used to obtain information about the nature of child play behaviors and level of engagement of 16 low-functioning children with ASD in the course of 12 weeks. All 16 children followed staff- and parent-mediated naturalistic interventions that yielded remarkable decrease in autism symptom severity, and gains in mental developmental state as well as in early language skills and adaptive functioning. At baseline, and each 4 weeks (4 total measurement-points) children’s social play and peer engagement was observed and rated in free play conditions.
Results: Preliminary results give insight in the areas of play and social engagement that can be facilitated by naturalistic adult-mediated interventions, highlighting at the same time skills areas that are lacking benefit and focused peer-mediated intervention is demanded. Play and peer engagement observation show after three month of one-to-one intervention a decrease in non-play behaviors and an increase in play behaviors, with increased quality and duration of functional toy-play while adult prompts decrease. Children demonstrate significant decrease in challenging behaviors such as stereotypes and auto-stimulation during free play, as well as an increase in child initiated interactions and directed communication with functional use of mutual eye contact and response of joint attention initiations. Nevertheless, these increases in pro-social reciprocity are related to social engagement with adults. It was shown that without adult initiation of parallel or group play, children with ASD engage in functional play at a solitary level of engagement.
The preliminary results verify that adult-mediated naturalistic intervention without focused peer-intervention facilitates the child’s functional play and pro-social engagement with limitation to the presence of an adult. Similar, finding to peer engagement are lacking. Anyhow, further analysis will account for the examination of collateral effects of behavior changes resulting from one-to-one intervention on social engagement. We will examine which areas addressed in one-to-one intervention (e.g. communication, cognitive skills, adaptive functioning) leads to collateral changes in non-targeted social engagement skills. Results will be presented at the conference.
[Show abstract][Hide abstract] ABSTRACT: Background: The ability to learn visuomotor procedures is particularly important for children, as it underlies the capacity to acquire the complex movement sequences that characterize communication environments, such as gestures or writing abilities. Recent studies have shown altered learning of visuomotor procedures in children with autistic spectrum disorders (ASD), using different visually guided motor tasks (i.e. serial reaction time and pursuit rotor task), underscoring how this may influence the development of appropriate social communicative skills. However, a task aimed at learning of visuomotor procedures, similar to handwriting, in children with ASD and easily employable in educational or clinical environments was still lacking.
Objectives: Inspired by the recent literature, we designed a computer-based program that allows, with the aid of a digital tablet, to evaluate learning of visuomotor procedures, similar to the ones involved in handwriting. After extensive trials on children with typical development, we conducted a preliminary study to assess the effectiveness of this program in evaluating these abilities in children with ASD.
Methods: Fourteen children participated to this pilot study: seven children with ASD (chronological age 7;7 ± 2.0; IQ 94.3 ± 19.0), seven children with typical development (TD, chronological age 7;4 ± 1.6; IQ 105.7 ± 12.7), matched on gender, chronological age and non-verbal cognitive level, evaluated using Raven’s Progressive Matrices. Overall visuomotor abilities of all children were also evaluated, using the VMI Test. The designed computer program required to track movements of a target presented on the computer screen using the digital pen and tablet. The program allowed to establish: overall time on target and overall distance from target, but it also allowed to reconstruct the movement strategies employed in the tracking process. Task trials were devised to evaluate effectiveness of the computer task in measuring: implicit visuomotor learning after practice, decrement in performance in presence of an altered stimulus, consolidation of acquired skills after a delay and specific strategies employed during learning.
Results: Showed that all children displayed implicit learning of the chosen visuomotor procedure, but children with ASD showed different performance, compared to children with TD, in presence of an altered stimulus, in relation to consolidation and in strategies adopted to track the moving target, therefore providing novel data on altered learning of visuomotor sequences in children with ASD.
Conclusions: Initial observations seem to indicate that this novel computer-based program may allow to gain a better understanding of specific aspects of visuomotor procedure learning, which are altered in children with ASD. Our future endeavor will be to better this tool in order to elaborate a program that may inform teachers and dedicated therapists on differential learning strategies adopted by children with ASD, while constructing a learning task that recruits abilities required during handwriting acquisition.
[Show abstract][Hide abstract] ABSTRACT: Background:
Research demonstrated that the inclusion of parents in treatment provision leads to lasting child behavior changes in children with ASD. Although it was shown that parent-treatment provision and parental stress are associated, there are considerable variability of its influence on child outcome. Findings vary from positive child outcome regardless treatment condition of a clinic- or parent-directed treatment, to increased parental stress due to high-intensive treatment provision, leading to reduced child outcomes. We did recently, extend previous research, and demonstrated that high parental stress interferes with professional decision making in treatment planning, leading to reduced behavior target difficulty regardless child’s skill level. Anyway, target choice due to parental stress rather than child pathology was shown to be dysfunctional, predicting an increase in child problem behaviors and decreased child performance on behavior targets. Research on parent treatment priorities, indicated that parent selected priorities had not yet been sufficiently effective addressed in treatment planning, with parents following mainly a deficit-based logic rather than a strength-based logic in selecting high priority areas.
The current study investigates (1) the association of parenting stress and selection of parent treatment priorities (2) how this association change in time, in a group of parents that followed a staff-and parent-mediated EIBI model for one year.
Children and their parents (N=40) followed a cross-setting staff- and parent-mediated EIBI treatment, following a 1 week center – 3 weeks home rhythm for 10 month. At treatment intake, after 5 month and at termination of treatment, parent identified their treatment priorities in relation to the child’s level of ability across a 8 domains of adaptive skills and problem behaviors, and indicated whether or not that skills was currently addressed in their child’s treatment program. The treatment priority survey was adapted from Pituch et al. (2011). Further, parents rated their level of parental stress on the Parenting Stress Index, Short Form. At 5 month and at the end of treatment parents rated their satisfaction with treatment on a survey adapted from Ingersoll and Dvortcsak (2006).
We do expect that parental distress is associated with selection of treatment priorities and respective unmet needs in treatment provision, influencing parent satisfaction with treatment. It is supposed that an increase in parenting stress is related to a deficit-based selection of treatment priorities and related amount of unaddressed skills in the child’s treatment program, whereas a decrease of parental stress is only achieved when the introduction of program targets are in accordance with parents indicated treatment needs.
Results offer insight in the relation of parental stress and the inclusion of parent-selected treatment priorities in treatment planning, deepen the current knowledge of a negative influence of parental stress on professional behavior target choice. Further analysis needs to examine a probable lack of concordance in selecting treatment priorities between staff and parent’s selection progress and how such lack of concordance counteract professional decision making in choosing appropriate treatment objectives.
[Show abstract][Hide abstract] ABSTRACT: The aim of this article was to explore the effect of duration of breastfeeding on neurocognitive development.
The long-term effect of breastfeeding on neurodevelopment was examined through a battery of neuropsychological tests in 1403 children (693 females, 710 males; mean age 11 y 9mo [SD 6mo], range: 10y 3mo-12y 8mo) who were originally recruited at 6 to 12 weeks of age for a clinical trial on acellular pertussis vaccines. An estimated IQ was obtained from scores of the vocabulary, similarities, block design, and coding tests. Breastfeeding data had been prospectively collected throughout the first year of life. Duration of exclusive breastfeeding was defined as the time during which children received breast milk without receiving any supplemental formula or food. Children were assessed at 10 to 12 years of age. We adjusted the analysis on test scores for multiple potential confounders.
Multivariate analysis showed a significant association between exclusive breastfeeding duration and test scores in the vocabulary (odds ratio [OR] 0.05; confidence interval [CI] 0.00-0.10; p=0.04) and similarities (OR 0.06; CI 0.01-0.11; p=0.03) tests. These associations have a negligible effect size, however. Scores on one writing praxis test subcategory decreased with increasing duration of both exclusive breastfeeding (OR -0.06; CI -0.11 to -0.01; p=0.03) and breastfeeding irrespective of consumption of other foods (OR -0.06; CI -0.11 to -0.01; p=0.03). A negative association was also found between one subcategory of the California verbal learning test and breastfeeding duration longer than 6 months (OR -0.21; CI -0.42 to -0.01; p=0.04).
Breastfed healthy children may perform better on neuropsychological tests in the language domain at 10 to 12 years of age. However, the effect of breast milk on neuropsychological performance in healthy children may have a limited clinical relevance and is confounded by parental education.
Full-text · Article · May 2012 · Developmental Medicine & Child Neurology
[Show abstract][Hide abstract] ABSTRACT: Although early intensive behavior interventions have been efficient in producing positive behavior outcome in young children with Autism Spectrum Disorder, there is a considerable variety in the children's progress. Research has suggested that parental and treatment factors are likely to affect children's response to treatment. The purpose of the current study was to examine the interrelating factors that impact children's progress, highlighting the influence of parent inclusion in treatment provision captured by parental stress, how faithfully the parents followed the treatment protocols and the intensity of treatment provided at home. Twenty-four children received cross-setting staff- and parent-mediated EIBI, including continuous parent training and supervision. A comparison group of 20 children received eclectic intervention. Standardized tests were carried out by independent examiners at intake and after six months. The intervention group outperformed the eclectic group in measures of autism severity, developmental and language skills. Parent training and constant parent-mediated treatment provision led to reduced challenging behaviors from the children, increased treatment fidelity and child direct behavior change as measured by performance in correct responding on behavior targets. Variables of treatment progress and potential predictors of child outcome were analyzed in detail and mapped with regard to their relationships drawn from multiple regression analysis. Particularly, the study highlights an association between parental stress and staff treatment fidelity that interferes with decision making in treatment planning and consequently with positive behavior outcome. Such results provide important scientific and clinical information on parental and treatment factors likely to affect a child's response to treatment.
Full-text · Article · Dec 2011 · Research in developmental disabilities
[Show abstract][Hide abstract] ABSTRACT: Background: Many authors have underscored impairment in intention understanding in autistic spectrum disorders (ASD), but only recently has research outlined in ASD the presence of specific impairments in intention understanding at the motor level during the observation of others’ actions. Motor intention understanding is an essential component of social cognition, as it allows to be efficiently attuned and to establish reciprocal communicative interactions with others. Two types of motor understanding are enrolled during the observation of others’ actions: understanding what specific motor act is being performed and understanding why an act is being performed. The first offers immediate perceptual information on the observed motor act, while the second foreshadows the other’s future actions and contributes to intention understanding. Neurophysiological data have shown that two different mechanisms underlie what and why comprehension and behavioral studies have highlighted how these two abilities follow specific developmental patterns in typical development (TD). Furthermore two different studies highlighted a specific impairment in why understanding in children with high-functioning autism and an impairment in what understanding in Williams syndrome (WS), a deficit also affecting social cognition and intention understanding.
Objectives: The main aim of this study was to better our understanding of what and why comprehension in ASD by comparing performance of younger children with low-functioning autism, children with WS and children with TD matched for mental age on a behavioral task. This would allow to evaluate whether impairment in motor intention understanding during the observation of simple motor acts: (a) proved to be different in ASD and in WS on comparable groups; (b) would present in ASD a similar developmental pattern to the one found in previous studies.
Methods: Participants (17 children with ASD, chronological age 8;7 ± 2.9, mental age 6;6 ± 1.4; 17 children with WS, chronological age 13;7 ± 6.9, mental age 6;6 ± 2.0; 18 children with TD, chronological age 6;2 ± 1.5, mental age 6;6 ± 1.9), were shown pictures depicting hand-object interactions (i.e. touching, grasping to use, grasping to put away) and where asked to indicate what action was being performed (i.e. touching or grasping) and why it was being performed (i.e. grasping to use or grasping to put away) in presence or in absence of contextual cues.
Results: Results showed (a) differential impairment in ASD and WS, i.e. a significant difference emerged between the ASD and WS groups on error rate when perticipants were required to indicate what action was being performed, WS group performing significantly worse than both ASD and TD groups; (b) differing developmental pattern in ASD, especially considering performance when participants were required to answer why the action was being performed in relation to previous studies on TD.
Conclusions: Behavioral data highlight a differential developmental pattern in the ability to understand others’ intentions at the level of simple motor actions in ASD, underscoring the importance of the distinction between what and why comprehension when considering understanding of specific differences in social skills present in ASD and WS.
[Show abstract][Hide abstract] ABSTRACT: Background:
Comprehensive treatment that start early and bases on the principles of ABA substantially improve outcomes in children with autism spectrum disorders. Research suggest that EIBI need to be delivered in many of the child’s daily environments to provide differential learning opportunities. Therefore, one of the most critical elements of including natural environments is the generalization of skills across settings and persons (Matson & Smith, 2008).
The current study investigated the effect of EIBI in preschoolers with ASD on standardized tests of severity in autism core symptoms (ADOS), developmental performance (GMDS-ER 2-8), adaptive behavior (VABS-II), language skills (CDI) and change in child’s problem behaviors.
12 children with ASD (10M:2F), range 26-71 month (M = 46.6 month, SD = 16.4), received a complementary staff- and parent-mediated EIBI treatment based on ABA-VB principles of 25 h/week in centre-based one-to-one (structured) and play room sessions (quasi naturalistic) and 14 h/week in home (naturalistic) (ABA-VB-group). Cross-setting treatment has been done in a 1 week centre – 3 weeks home rhythm for 12 month with a initial 3 week parent training period, to accomplish maintenance and generalization of skills acquired at the clinical setting in a natural environment of the children (Fava & Strauss, 2011). The ABA-VB group was compared with 10 children with ASD (9M:1F), range 28-66 month (M = 43.7 month, SD = 12.5) that received Eclectic interventions for 16 h/week (psicomotricity, speech therapy, music therapy and uncontrolled in-home ABA). All children followed initial 6 month of the full 12 month treatment. Statistical analysis have been performed using R software. Mean scores before and after the therapy have been compared using paired T-tests.
After the initial 6 month, a independent examination of a child psychiatrist revealed that there was a significant decrease in ADOS scores in the ABA-VB-group (total: p<.001; communication: p<.05, social interaction: p<.01) and GMDS-ER 2-8 scores show a significant improvement of developmental state (QS: p<.01) as well as the CDI language skills scores (comprehension: p.<01, speaks: p.<05) while the eclectic group did not show any significant change. VABS-II scores increased significantly in both the ABA-VB-group (p<.01) and the eclectic group (p<.01). Furthermore, within the ABA-VB group problem behaviors decreased significantly (aggressive behavior p<.001, stereotypes p<.001 and dysfunctional behavior p<.0001).
Our results point to effectiveness of a staff- and parent mediated EIBI program based on ABA-VB for children with ASD for reducing symptom severity and problem behaviors as well as improving the development state, adaptive behaviors and language skills. These finding highlight the importance of generalization across setting and persons and focalize the attention on verbal behavior and incidental teaching for improving functional behavior in various environments that result in reduced problem behaviors and increased language skills. As adaptive behaviors do significantly improve in both study groups, the results will be discussed to specify potential factors that facilitate the generalization of such skills and to help professionals and parents in their program application to maximize EIBI efforts.
[Show abstract][Hide abstract] ABSTRACT: Background: The social impairment, communicative, attentive and play skills shared reduce opportunities for children with Autism and Pervasive Developmental Disorder (PDD) to take advantage of natural experiences of everyday interaction. The development of socio-communicative skills in PDD was, in fact, the goal of many research from which they originated many types of therapeutic intervention.
Objectives: Among the treatments currently used in our contribution concerns a model of Therapy Mediated by Parents (TMG) experienced at the outset, at the UOC Neuropsychiatry Unit of “Bambino Gesù” Children's Hospital in Rome. This model aims to enhance mutual communication and social interaction in a setting starring children and their parents. They become mediators of the proposed therapy in the clinical setting, proposing it to the child in his daily environment.
Methods: We created a detailed manual of the TMG’s steps which each operator is required to follow. In order to standardize the treatment all therapists had one meeting per month (6 monthly meetings) before and after the treatment verifying the adherence to the manuals. The sample consisted of 26 children with DGS who followed a cognitive-behavioral therapy by up to 6 months. The subjects belonging to the two groups were matched 1:1 for age, sex and diagnosis according to DSM IV.
Results: The comparison between the two groups after treatment showed a significant difference in the communications’ scales for the group that followed the TMG.
Conclusions: A first analysis of data shows a statistically significant difference between the experimental group and control groups in the areas of communication, measured by ADOS and percentage of children who become verbal (use of more than 5 words). In order to further verify the effectiveness of the treatment we propose to increase the sample, systematically measure and carry out follow up at 6 months and a year.
[Show abstract][Hide abstract] ABSTRACT: Background:
Research indicates that parental stress counteract the effectiveness of EIBI programs. Recent results suggest both, that stress decreases when parents provide intervention as well as that involvement increases stress. Less research focused on factors interfering with changes in parent’s stress over time during implementing interventions and its relation to treatment outcomes. It is supposed that stress does not directly impact the child’s outcome, rather than it is mediated by a function of intense inclusion and parental stress.
To determine how parental stress change during a 6 month period out of a 1 year program and if parent stress affect the child’s outcome. Further, to determine how parent’s involvement and treatment fidelity interfere the relationship between parental stress levels and child outcomes.
12 children with ASD (10M:2F; Mage= 46.6 month, SD = 16.4), received a staff- and parent-mediated EIBI treatment based on ABA-VB in centre-based one-to-one, play room and home sessions (ABA-VB-group). Treatment followed a 1 week centre – 3 weeks home rhythm for 12 month to accomplish maintenance and generalization of skills. Initial 3 weeks parent training included intensive theoretical and practical training. Outcomes of the ABA-VB group was compared with 10 children (9M:1F; Mage= 43.7 month, SD = 12.5) that received eclectic interventions (psicomotricity, speech therapy, uncontrolled in-home ABA). Repeated measures have been calculated using paired T-tests, influences on outcomes using linear regressions.
After 6 month, parental stress decreased significantly in the eclectic group (p.<.05) while remained stable in the ABA-VB group with having significantly more stress (p<.01). While decreased stress positively impact the eclectic group in language (CDI comprehension p<.001, CDI speaks p<.001) and developmental state (GMDS-ER QS p<.001), such effect does not appear in the ABA-VB group. Findings are incoherent since the ABA-VB group showed better outcome for ADOS (total: p<.001), GMDS-ER 2-8 (QS: p<.01), and CDI language skills (comprehension: p.<01, speaks: p.<05) while the eclectic group did not significantly change. Consistent with our focus on parent inclusion, in average 174 targets have been worked on (SD=75.5, range 55-343) with an average of 60% introduced, mastered and generalized by the parent (SD=15.9; range 29.5%-81.6%). The treatment fidelity of parents increased in data collection (p<.001), facilitated play (p.<01), training of new targets (p<.01) and mastered targets (p<.01). Intensity of treatment application and treatment fidelity of parents does not interfere neither with parental stress nor with child’s outcome.
Parental stress, treatment fidelity and intensity does not directly interfere child’s outcome nor parental stress directly derived by parents treatment fidelity or effort to provide treatment. A detailed evaluation of the child’s treatment progress has been followed controlling weekly the mastery and generalization of introduced targets, providing variables such as speed of learning and change of acquisition rates over time, appropriateness of targets chosen by the supervisor and effectiveness of the parent-supervisor relation in controlling and forwarding child’s progress. A progress model is aimed to include those variables and is charged to explain how our treatment effects are mediated. Results will be presented at the conference.
[Show abstract][Hide abstract] ABSTRACT: TITLE:
Emotional and behavioral problems in prescholars children with autism and PDD NOS: prevalence and risk factor
Children with autism spectrum disorders (ASD) often exhibit behaviour and emotional problems that negatively impact everyday activities. Maladaptive behaviours can also interfere with intervention efforts and thereby impact the long-term prognosis of children with ASD.
The purpose of this study is to identify:
(1) the prevalence of Clinically Significant maladaptive behaviours through parent report on the CBCL of 101 children diagnosed with AD and PDD NOS aged 2.2 to 5.11 years and determine the similarities or dissimilarities;
(2) subject characteristic risk factors for maladaptive behaviours (such gender, age, expressive language, severity of autistic behaviours, adaptive behaviour and regression of language or social skills);
(3) parent-factors, such age, cultural and socioeconomic differences, family characteristic, influenced parent ratings of maladaptive behaviours.
101 children, aged 2.2 to 5.11 years, were recruited consecutively at the Children’s Hospital Bambino Gesù in Rome between May 2009 and July 2010 and diagnosed with PDD (Pervasive Developmental Disorders) based on criteria of DSM-IV TR.
Parents completed the Child Behavior Checklist for ages 1.5 through 5 years (CBCL, Achenbach & Rescorla 2000) and the short form Italian version of the MacArthur Communicative Development Invertories (PVB, Caselli et al. 2007); they also participated in the Vineland Adaptive Behaviour Scales, Interview Form (VABS, Sparrow et al. 2005) and the Autism Diagnostic Interview-Revised (ADI-R, Lord et al. 2000).
Children were individually administered the Autism Diagnostic Observation Schedule-Generic (ADOS-G, Lord et al. 2000) by licensed professionals.
One-third of young children with ASD (AD and PDD NOS) had a CBCL Total Problems score in the Clinically Significant range. The highest percentage of Clinically Significant scores were in the Withdrawal, Attention, and Somatic Complaints CBCL syndrome scales.
We performed univariate logistics to estimate association between each single CBCL subscale and groups (AD or PDD-NOS): only one univariate logistic was statistically significant, and show that AD group have 80% lower probability than PDD-NOS group to have affective problems
We have also identified several subject and parent characteristic risk factors for maladaptive behaviours: children’s age, expressive language and severity of autistic behaviours, and mother’s education and occupation.
An investigation of the subject characteristic correlates of maladaptive behaviours in young children with ASD is needed to identify at-risk subgroups. This research must be extented to which parent-factors, such as cultural and socioeconomic differences, influenced parent ratings of maladaptive behaviours.
[Show abstract][Hide abstract] ABSTRACT: The aim of the study was to analyse the characteristics of domestic violence by comparing a sample of children who witnessed abuse against a sample of children who suffered from it, and to outline how the traumatic experience could influence the child's emotional, cognitive and psychopathological development. Thirty-three school-age children (14 girls and 19 boys) aged between 6 and 11 years of age were studied; 17 out of 33 were witnesses of violence (WA; age Mean (M) 8.8; Standard Deviation (SD) 1.4), and 16 out of 33 suffered from sexual abuse or physical maltreatment (SPA; age M 8.7; DS 1.4). All children have been assessed by the K-SADS-PL (Schedule for Affective Disorders and Schizophrenia for School-age Children – Present and Lifetime Version) interview, the projective test of Duss Fables and the Promea battery of tests, which investigate the cognitive function of memory. The presence of behavioural disorders (WA > SPA), post-traumatic stress disorder (WA < SPA) and also anxiety disorders (WA = SPA) emerged from the study. The Duss Fables method highlighted areas of conflict. The Promea test draws attention to the performance of all abused children being average, but different learning styles emerged from implicit learning (WA > SPA) and implicit and explicit visual learning (WA > SPA). The comparison between the two samples has shed light on areas of specific vulnerability concerning psychopathological, emotional and cognitive aspects of development.
Full-text · Article · Dec 2009 · Paediatrics and Child Health
[Show abstract][Hide abstract] ABSTRACT: Thimerosal, a mercury compound used as a preservative in vaccines administered during infancy, has been suspected to affect neuropsychological development. We compared the neuropsychological performance, 10 years after vaccination, of 2 groups of children exposed randomly to different amounts of thimerosal through immunization.
Children who were enrolled in an efficacy trial of pertussis vaccines in 1992-1993 were contacted in 2003. Two groups of children were identified, according to thimerosal content in vaccines assigned randomly in the first year of life (cumulative ethylmercury intake of 62.5 or 137.5 microg), and were compared with respect to neuropsychological outcomes. Eleven standardized neuropsychological tests, for a total of 24 outcomes, were administered to children during school hours. Mean scores of neuropsychological tests in the domains of memory and learning, attention, executive functions, visuospatial functions, language, and motor skills were compared according to thimerosal exposure and gender. Standard regression coefficients obtained through multivariate linear regression analyses were used as a measure of effect.
Nearly 70% of the invited subjects participated in the neuropsychological assessment (N = 1403). Among the 24 neuropsychological outcomes that were evaluated, only 2 were significantly associated with thimerosal exposure. Girls with higher thimerosal intake had lower mean scores in the finger-tapping test with the dominant hand and in the Boston Naming Test.
Given the large number of statistical comparisons performed, the few associations found between thimerosal exposure and neuropsychological development might be attributable to chance. The associations found, although statistically significant, were based on small differences in mean test scores, and their clinical relevance remains to be determined.