دانلود رایگان ترجمه مقاله سنتز و متاآنالیز هماهنگی حرکتی در اختلالات طیف اوتیسم (نشریه اسپرینگر 2010)

هماهنگی حرکتی در اختلالات طیف اوتیسم: یک سنتز و متاانالیز

Motor Coordination in Autism Spectrum Disorders: A Synthesis and Meta-Analysis

Abstract

Are motor coordination deficits an underlying cardinal feature of Autism Spectrum Disorders (ASD)? Database searches identified 83 ASD studies focused on motor coordination, arm movements, gait, or postural stability deficits. Data extraction involved between-group comparisons for ASD and typically developing controls (N = 51). Rigorous meta-analysis techniques including random effects models, forest and funnel plots, I 2 , publication bias, fail-safe analysis, and moderator variable analyses determined a significant standardized mean difference effect equal to 1.20 (SE = 0.144; p\0.0001; Z = 10.49). This large effect indicated substantial motor coordination deficits in the ASD groups across a wide range of behaviors. The current overall findings portray motor coordination deficits as pervasive across diagnoses, thus, a cardinal feature of ASD.

1 Introduction

Autism Spectrum Disorders (ASD) is an inclusive term for a group of neurodevelopmental disorders sharing similar impairments in communication, reciprocal social interaction, and restricted, repetitive behavior. While similar in nature, ASD includes the following distinct diagnoses: autism, Asperger’s Syndrome, and Pervasive Developmental Disorder-Not Otherwise Specified (DSM-IV 2000; Tanguay et al. 1998). Recent epidemiological studies provide prevalence estimates in the 60–70/10,000 range, making ASD one of the most frequently observed childhood neurodevelopmental disorders (Fombonne 2009). Although current improvements in diagnostic criteria and refined methodologies may be contributors, the prevalence appears to have increased in recent surveys (Bertoglio and Hendren 2009; Fombonne 2009; Lenoir et al. 2009). Given the frequency reports, not surprisingly, both the lay and scientific communities have rapidly increased their attention to the diagnostic and cardinal features of ASD.

One ASD associated feature requiring more elucidation is disturbances in motor behavior. The literature focusing on gross motor behavior and development in ASD is plagued by inconsistent findings. Early views stressed that children with ASD may have similar motor development (Hallett et al. 1993; Mayes and Calhoun 2003) or perhaps even more advanced motor skills than their peers (Johnson and Myers 2007; Rimland 1964). However, more frequently reported, ASD is associated with greater clumsiness, motor coordination abnormalities, postural instability, and poor performance on standardized tests of motor functioning (Bauman 1992; Ghaziuddin and Butler 1998; Jones and Prior 1985; Kohen-Raz et al. 1992; Molloy et al. 2003; Rapin 1997; Rogers et al. 1996; Vilensky et al. 1981). Further complicating our understanding of the underlying motor features is that several studies failed to detect differences between children with ASD and those with learning disabilities or mental retardation (Morin and Reid 1985), general developmental delay (Provost et al. 2007b), and language disorders (Noterdaeme et al. 2002) across reflexive, intentional, fine and gross motor tasks. These observations challenge whether disturbed motor performances in ASD are because of alterations in the motor circuits, gross brain dysfunction, or a behavioral byproduct of the interaction between motor function and other core features of ASD. Thus, while these cross-sectional studies provide critical information regarding the types of motor impairments seen in ASD, the specific patterns and sources of motor deficits in this population remain unclear (Noterdaeme et al. 2002).

Other approaches to elucidating motor components of ASD include neural signaling. Abnormal transmission in the serotonergic, dopaminergic, and GABAergic systems, frequently observed in ASD, may potentially affect motor performance (Cook et al. 1997; DeLorey et al. 1998; Nelson et al. 2001). Further, imaging studies have identified significant anomalies within seminal structures controlling motor behavior in individuals with ASD. Indeed, structural imaging studies suggest that individuals with ASD have larger total brain, cerebellar and caudate nucleus volumes; however, the area of the corpus callosum is reduced (for recent reviews see: Hrdlicka 2008; Stanfield et al. 2008). Functional MRI studies have also identified differential activation in brain areas related to motor performances in children with ASD, suggesting a reliance on alternative pathways (Verhoeven et al. 2010). Thus, there appears to be neurobiological underpinning for the clinically observed motor deficits in ASD.

Novel attempts to relate motor impairments in infancy to the onset characteristics of ASD have produced intriguing findings (Teitelbaum et al. 1998). Indeed, several related studies in which motor behavior was evaluated using home videos of children later diagnosed with ASD compared to typically developing children demonstrated motor differences within the first 2 years of age (Adrien et al. 1993; Baranek 1999; Teitelbaum et al. 2004). Though, Ozonoff et al. (2007) failed to replicate these findings. Taken together, this evidence suggests that motor deficits may be present even before communicative or social deficits, implying that impaired motor behavior may underlie an apparent ASD core characteristic (Leary and Hill 1996; Nayate et al. 2005). Certainly, impaired perceptual-motor difficulties can exacerbate other core symptoms by limiting interaction with the physical and social world during critical developmental periods.

Consequently, the delayed onset of motor capabilities and coordination deficits with a distinct association to ASD are of fundamental importance. However, the literature is overflowing with conflicting results, methodological insufficiencies, and highly variable ASD participants and comparison groups across studies. Further, observed results may be biased by the influence of moderating variables such as age and intelligence quotient. Each of these concerns severely obscures our understanding of motor impairments in this population. Thus, an appealing alternative approach that aptly integrates the varied literature and findings is a robust, systematic review and meta-analysis. Conducting a meta-analysis on ASD is an objective and quantitative technique for summarizing the presence of motor control impairments and determining summary effect sizes as well as gaining fundamental insight. Therefore, using the metaanalytic technique, we asked two critical questions:

(1) Do motor control capabilities and/or impairments distinguish children and adults with ASD when compared to neurologically, typically developing normal age-matched controls? (2) Do upper or lower extremities motor control impairments distinguish children and adults within ASD?