A systematic review and meta-regression analysis of social functioning correlates in autism and typical development

Loneliness in daily life: A comparison between youths with autism spectrum disorders and 22q11.2 deletion syndrome (22q11DS)

Loneliness is a negative emotional experience that can stem from a gap between desires and the reality of social relationships. It is also a predictor of mental health. Loneliness is therefore important to investigate in neurodevelopmental populations known for having difficulties in the social sphere. This co-registered study involved 48 youths with autism spectrum disorders (ASD), 54 youths with 22q11.2 deletion syndrome (22q11DS) and 65 typically developing youths (TD) aged 12-30. State loneliness was assessed with an ecological momentary assessment. Paper-pencil questionnaires assessing attitude toward aloneness, trait loneliness, and mental health, were completed by the youths and their caregivers. A comparable level of state loneliness between clinical groups and TD were found, with greater loneliness when alone than in a social context. Clinical groups showed a greater intra-individual variability. Both individuals with ASD and 22q11DS revealed a greater affinity toward being alone than TD, but only individuals with ASD reported greater trait loneliness. However, no significant association was found between attitude toward aloneness, trait and state loneliness. Emotional reactivity to loneliness was different between the clinical groups. Self-reported mental health only was associated with loneliness in the clinical groups. These results provide new insights into the understanding of loneliness in these clinical populations and have an impact on clinical care by highlighting the need to remain vigilant when encountering youths who report feeling lonely, and that these youths need to be supported in developing their social network, which appears to be a protective factor against loneliness.

Distinct social behavior and inter-brain connectivity in Dyads with autistic individuals

Autism Spectrum Disorder (ASD) is defined by distinctive socio-cognitive behaviors that deviate from typical patterns. Notably, social imitation skills appear to be particularly impacted, manifesting early on in development. This paper compared the behavior and inter-brain dynamics of dyads made up of two typically developing (TD) participants with mixed dyads made up of ASD and TD participants during social imitation tasks. By combining kinematics and EEG-hyperscanning, we show that individuals with ASD exhibited a preference for the follower rather than the lead role in imitating scenarios. Moreover, the study revealed inter-brain synchrony differences, with low-alpha inter-brain synchrony differentiating control and mixed dyads. The study's findings suggest the importance of studying interpersonal phenomena in dynamic and ecological settings and using hyperscanning methods to capture inter-brain dynamics during actual social interactions.

Differences in Praxis Errors in Autism Spectrum Disorder Compared to Developmental Coordination Disorder

This study aimed to better understand how autism spectrum disorder (ASD) and developmental coordination disorder (DCD) differ in types of praxis errors made on the Florida Apraxia Battery Modified (FAB-M) and the potential relationships between praxis errors and social deficits in ASD. The ASD group made significantly more timing sequencing errors in imitation of meaningful gestures, as well as more body-part-for-tool errors during gesture-to-command compared to the other two groups. In the ASD group, increased temporal errors in meaningful imitation were significantly correlated with poorer affect recognition and less repetitive behaviors. Thus, in ASD, aspects of imitation ability are related to socioemotional skills and repetitive behaviors.

Linearly integrating speed and accuracy to measure individual differences in theory of mind: Evidence from autistic and neurotypical adults

It has long been theorised that there is a direct link between individual differences in social cognition and behaviour. One of the most popular tests of this theory has involved examination of Theory of Mind (ToM) difficulties in Autism Spectrum Disorder (ASD). However, evidence for associations between ToM and social behaviour is mixed, both when testing the ToM explanation of ASD and when investigating individual differences in ToM in the general population. We argue that this is due to methodological limitations of many ToM measures, such as a lack of variability in task performance, inappropriate non-ToM control tasks, and a failure to account for general mental ability. To overcome these issues, we designed a novel task, which probed individual differences in ToM fluency through mental state attribution in response to cartoons (Cartoons Theory of Mind [CarToM] task). This task, enabling the linear combination of speed and accuracy, was used to quantify ToM ability and its association with self-reported (a)typical social behaviour in adults with and without ASD. In a large sample (N = 237), we found that having an ASD diagnosis and higher autistic traits predicted lower ToM ability, even after accounting for performance on a well-matched non-ToM condition and general mental ability. Overall, our findings provide fresh support for the existence of a link between individual differences in social cognition (specifically, ToM) and behaviour (specifically, autism). This has implications for social-cognitive theory and research, allowing large-scale, online assessment of individual differences in ToM in clinical groups and the general population.

Neural correlates of audiovisual narrative speech perception in children and adults on the autism spectrum: A functional magnetic resonance imaging study

Autistic individuals show substantially reduced benefit from observing visual articulations during audiovisual speech perception, a multisensory integration deficit that is particularly relevant to social communication. This has mostly been studied using simple syllabic or word-level stimuli and it remains unclear how altered lower-level multisensory integration translates to the processing of more complex natural multisensory stimulus environments in autism. Here, functional neuroimaging was used to examine neural correlates of audiovisual gain (AV-gain) in 41 autistic individuals to those of 41 age-matched non-autistic controls when presented with a complex audiovisual narrative. Participants were presented with continuous narration of a story in auditory-alone, visual-alone, and both synchronous and asynchronous audiovisual speech conditions. We hypothesized that previously identified differences in audiovisual speech processing in autism would be characterized by activation differences in brain regions well known to be associated with audiovisual enhancement in neurotypicals. However, our results did not provide evidence for altered processing of auditory alone, visual alone, audiovisual conditions or AV- gain in regions associated with the respective task when comparing activation patterns between groups. Instead, we found that autistic individuals responded with higher activations in mostly frontal regions where the activation to the experimental conditions was below baseline (de-activations) in the control group. These frontal effects were observed in both unisensory and audiovisual conditions, suggesting that these altered activations were not specific to multisensory processing but reflective of more general mechanisms such as an altered disengagement of Default Mode Network processes during the observation of the language stimulus across conditions.

Language acquisition can be truly atypical in autism: Beyond joint attention

Language profiles in autism are variable and atypical, with frequent speech onset delays, but also, in some cases, unusually steep growth of structural language skills. Joint attention is often seen as a major predictor of language in autism, even though low joint attention is a core characteristic of autism, independent of language levels. In this systematic review of 71 studies, we ask whether, in autism, joint attention predicts advanced or only early language skills, and whether it may be independent of language outcomes. We consider only conservative estimates, and flag studies that include heterogenous samples or no control for non-verbal cognition. Our review suggests that joint attention plays a pivotal role for the emergence of language, but is also consistent with the idea that some autistic children may acquire language independently of joint attention skills. We propose that language in autism should not necessarily be modelled as a quantitative or chronological deviation from typical language development, and outline directions to bring autistic individuals' atypicality within the focus of scientific inquiry.

Connectivity differences between inferior frontal gyrus and mentalizing network in autism as compared to developmental coordination disorder and non-autistic youth

Prior studies have compared neural connectivity during mentalizing tasks in autism (ASD) to non-autistic individuals and found reduced connectivity between the inferior frontal gyrus (IFG) and mentalizing regions. However, given that the IFG is involved in motor processing, and about 80% of autistic individuals have motor-related difficulties, it is necessary to explore if these differences are specific to ASD or instead similar across other developmental motor disorders, such as developmental coordination disorder (DCD). Participants (29 ASD, 20 DCD, 31 typically developing [TD]; ages 8-17) completed a mentalizing task in the fMRI scanner, where they were asked to think about why someone was performing an action. Results indicated that the ASD group, as compared to both TD and DCD groups, showed significant functional connectivity differences when mentalizing about other's actions. The left IFG seed revealed ASD connectivity differences with the: bilateral temporoparietal junction (TPJ), left insular cortex, and bilateral dorsolateral prefrontal cortex (DLPFC). Connectivity differences using the right IFG seed revealed ASD differences in the: left insula, and right DLPFC. These results indicate that connectivity differences between the IFG, mentalizing regions, emotion and motor processing regions are specific to ASD and not a result of potentially co-occurring motor differences.

Theory of Mind Predicts Social Interaction in Children with Autism Spectrum Disorder: A Two-Year Follow-Up Study

This two-year follow-up study examined the predictive relationships of theory of mind (ToM) to social interaction by reciprocal social behaviors (RSBs) and social functioning (SF) in 106 children with ASD. The results of the path analysis showed that the earlier ToM predicted children's current component RSBs (B = 3.53, SE = 1.86, p = 0.039) and the current SF (B = 1.79-1.87, SE = 0.03-0.34, p < 0.001). The aloof and passive social interaction styles predicted fewer turn-taking of RSBs (B =  - 48.77 to - 111.17, p < 0.001) and fewer components of RSBs (B =  - 36.30 to - 81.41, p < 0.001). This finding provides empirical evidence that ToM predicts social interaction in children with ASD.

The transition to college: lived experiences of academically talented students with autism

The experiences of autistic college students have become an increasing focus of research over the past 10 years. As a part of a larger research project, 40 successful autistic college students were interviewed about their experiences transitioning from high school to college. Participants reported being active participants in selecting colleges, but not receiving robust transition services during high school. They reported wanting additional opportunities in high school to develop executive function skills and to have more social opportunities. Further, they stressed the importance of developing greater independence while in high school.

Guidance for Increasing Primary Study Inclusion and the Usability of Data in Meta-Analysis: A Reporting Tutorial

Meta-analyses can be used to comprehensively summarize the state of a given literature base, understand development and relations between constructs, and synthesize intervention effects to identify "what works for whom," all of which can directly inform research, practice, and policy. In this tutorial, we first argue that data reporting in primary studies can meaningfully affect the results of meta-analyses and, most importantly, the subsequent interpretations and use of the findings in research, practice, and policy in speech, language, and hearing sciences. Though reporting guidelines have been well established for the results of meta-analyses, there is limited focus on the essentials for primary study reporting that allow for inclusion in meta-analyses. To this end, we provide guidance for primary study authors to ensure their studies can maximize their contributions to research syntheses and, specifically, to meta-analyses. We discuss current and ongoing issues related to reporting, provide data-based examples of instances where lack of reporting or transparency has rendered a study ineligible from inclusion in a meta-analysis, encourage editorial teams and peer reviewers to be flexible in the inclusion of supplemental data reporting based on journal requirements and limits, and suggest being explicit and earnest about why these requests are important to advancing the field. Supplemental Material: https://doi.org/10.23641/asha.23117996.

Friendship quality among autistic and non-autistic (pre-) adolescents: Protective or risk factor for mental health?

Autistic young people are often misunderstood by non-autistic young people, and this can lead to difficulties in their friendships. We know that friendship is very important for our mental health. For non-autistic young people, having good friendships is linked to better mental health and having problems in friendship can cause mental health problems. This study aimed to compare the positive and negative features of friendship that autistic non-autistic young people experience. The study also aimed to understand if having positive or negative friendship features is related to signs of mental health problems (anxiety and depression). 306 young people aged 9-16 took part in this study. These were 86 autistic boys, 18 autistic girls, 91 non-autistic boys and 111 non-autistic girls. The findings of this study showed that autistic young people have less positive friendship features than non-autistic young people. For all young people in the study, having more positive friendship features was related to fewer signs of depression, while having more negative friendship features was related to more signs of depression. Just for autistic girls, having more positive friendship features was related to more signs of anxiety. These findings show that support is needed to help autistic young people have more positive friendships. For example, by teaching non-autistic young people how to be supportive friends to their autistic peers.

Face-to-face learning enhances the social transmission of information

Learning from others provides the foundation for culture and the advancement of knowledge. Learning a new visuospatial skill from others represents a specific challenge-overcoming differences in perspective so that we understand what someone is doing and why they are doing it. The "what" of visuospatial learning is thought to be easiest from a shared 0° first-person perspective and most difficult from a 180° third-person perspective. However, the visual disparity at 180° promotes face-to-face interaction, which may enhance learning by scaffolding social perspective taking, the "why" of visuospatial learning. We tested these potentially conflicting hypotheses in child and young adult learners. Thirty-six children (4-6 years) and 57 young adults (18-27 years) observed a live model open a puzzle box from a first-person (0°) or third-person (90° or 180°) perspective. The puzzle box had multiple solutions, only one of which was modelled, which allowed for the assessment of imitation and goal emulation. Participants had three attempts to open the puzzle box from the model's perspective. While first-person (0°) observation increased imitation relative to a 180° third-person perspective, the 180° observers opened the puzzle box most readily (i.e., fastest). Although both age groups were excellent imitators and able to take the model's perspective, adults were more faithful imitators, and children were more likely to innovate a new solution. A shared visual perspective increased imitation, but a shared mental perspective promoted goal achievement and the social transmission of innovation. "Perfection of means and confusion of goals-in my opinion-seem to characterize our age" Einstein (1973) pg 337, Ideas and Opinions.

Imbalanced Gamma-band Functional Brain Networks of Autism Spectrum Disorders

Resting gamma-band brain networks are known as an inhibitory component in functional brain networks. Although autism spectrum disorder (ASD) is considered as with imbalanced brain networks, the inhibitory component remains not fully explored. The study reported 10 children with ASD and 10 typically-developing (TD) controls. The power spectral density analysis of the gamma-band signal in the cerebral cortex was performed at the source level. The normalized phase transfer entropy values (nPTEs) were calculated to construct brain connectivity. Gamma-band activity of the ASD group was lower than the TD children. The significantly inhibited brain regions were mainly distributed in the bilateral frontal and temporal lobes. Connectivity analysis showed alterations in the connections from key nodes of the social brain network. The behavior assessments in the ASD group revealed a significantly positive correlation between the total score of Childhood Autism Rating Scale and the regional nPTEs of the right transverse temporal gyrus. Our results provide strong evidence that the gamma-band brain networks of ASD children have a lower level of brain activities and different distribution of information flows. Clinical meanings of such imbalances of both activity and connectivity were also worthy of further explorations.

Heterogeneity thwarts autism explanatory power: A proposal for endophenotypes

Many researchers now believe that autism heterogeneity is likely to include many disorders, but most research is based on samples defined by the DSM-5 Autism Spectrum Disorder (ASD) criteria. However, individuals diagnosed with autism have complex and varied biological causes for their symptoms. Therefore, autism is not a unitary biological entity. And although autism is significantly different from typical development, autism is not a unitary clinical disorder because diagnosed individuals vary in symptom patterns, comorbidities, biomarkers, and gene variants. The DSM-5 ASD criteria were designed to reduce heterogeneity, and there have been many other efforts to reduce autism heterogeneity including using more stringent clinical criteria, dividing autism into low and high functioning groups, creating subgroups, and by studying larger samples. However, to date these efforts have not been successful. Heterogeneity is extensive and remains unexplained, and no autism pathophysiology has been discovered. Most importantly, heterogeneity has hindered the explanatory power of the autism diagnosis to discover drug regimens and effective behavioral treatments. The paper proposes that possible transdiagnostic endophenotypes may reduce autism heterogeneity. Searching for transdiagnostic endophenotypes requires exploring autism symptoms outside of the framework of the DSM-5 autism diagnosis. This paper proposes that researchers relax diagnostic criteria to increase the range of phenotypes to support the search for transdiagnostic endophenotypes. The paper proposes possible candidates for transdiagnostic endophenotypes. These candidates are taken from DSM-5 ASD criteria, from concepts that have resulted from researched theories, and from symptoms that are the result of subtyping. The paper then sketches a possible basis for a future transdiagnostic endophenotypes screening tool that includes symptoms of autism and other neurodevelopmental disorders.

Design of an Interactive Virtual Reality System, InViRS, for Joint Attention Practice in Autistic Children

Many children with Autism Spectrum Disorder (ASD) exhibit atypical gaze behaviors related to joint attention, a fundamental social-communication skill. Specifically, children with ASD show differences in the skills of gaze sharing and gaze following. In this work we present a novel virtual reality (VR)-based system, called InViRS, in which children with ASD play games allowing them to practice gaze sharing and gaze following. InViRS has three main design contributions: (i) a closed-loop joint attention paradigm with real-time tracking of the participant’s eye gaze and game performance measures, (ii) an assistive feedback mechanism that provides guidance and hints in real time, and (iii) a controller that adaptively changes the avatar’s gaze prompts according to the performance measures. Results from a pilot study to evaluate the feasibility of InViRS with 9 autistic¹ children and 9 typically developing (TD) children offered preliminary support for the feasibility of successful gameplay as well as positive impacts on the targeted skills of gaze sharing and gaze following.

Levels of Self-representation and Their Sociocognitive Correlates in Late-Diagnosed Autistic Adults

The cognitive representation of oneself is central to other sociocognitive processes, including relations with others. It is reflected in faster, more accurate processing of self-relevant information, a “self-prioritisation effect” (SPE) which is inconsistent across studies in autism. Across two tasks with autistic and non-autistic participants, we explored the SPE and its relationship to autistic traits, mentalizing ability and loneliness. A SPE was intact in both groups, but together the two tasks suggested a reduced tendency of late-diagnosed autistic participants to differentiate between familiar and unfamiliar others and greater ease disengaging from the self-concept. Correlations too revealed a complex picture, which we attempt to explore and disentangle with reference to the inconsistency across self-processing studies in autism, highlighting implications for future research.

Social cognition following preterm birth: A systematic review

Social cognitive abilities are affected by preterm birth, but pathways to, and risk factors for this outcome are not well mapped. We examined direct assessment tasks including objective coding of parent-child play to chart social development in infancy and pre-school years. A systematic search and data-extraction procedure yielded seventy-nine studies (4930 preterm and 2109 term children, aged birth - five years), for inclusion. We detected a pattern of reduced social attention in the first 12 months of life with evidence of reduced performance in social cognitive tasks later in the preschool years. However, we did not identify a consistent, distinctive preterm social phenotype in early life. Instead, the interactive behaviour of preterm infants reflects factors from outside the social cognitive domain, such as attention, language, and socioeconomic status. By combining data across samples and measures we revealed the role of domain-general skills, which may in future prove fruitful intervention targets.

Adapting and validating the Autism Diagnostic Observation Schedule Version 2 for use with deaf children and young people

We report a Delphi Consensus modification and first validation study of the Autism Diagnostic Observation Schedule - 2 with deaf children and young people (ADOS-2 Deaf adaptation). Validation included 122 deaf participants (aged 2-18 years), 63 with an Autism Spectrum Disorder (ASD). This was compared to a National Institute for Health and Clinical Excellence (NICE) guideline standard clinical assessment by blinded independent specialist clinicians. Results showed overall sensitivity 73% (95%CI 60%, 83%); specificity 71% (95%CI 58%, 82%), and for the more common modules 1-3 (combined as in previous studies) sensitivity 79% (95% CI 65-89%); specificity 79% (95% CI 66-89%) suggesting this instrument will be a helpful addition for use with deaf children and young people.

Developmental associations between joint engagement and autistic children's vocabulary: A cross-lagged panel analysis

LAY ABSTRACT

In this study, we used a cross-lagged panel analysis to examine correlations over time between two types of engagement between children and their parents and children's later expressive and receptive vocabularies. This kind of design can help researchers understand which early developmental achievements "drive" later developmental achievements. It is important for intervention researchers to know which developmental achievements happen first, so that they can set intervention goals appropriately. The two joint engagement variables we examined were (a) higher order supported joint engagement, which occurs when caregivers influence their child's play with toys and the child reciprocally responds to the caregiver, but does not manage the interaction by shifting gaze between the toys and the caregiver, and (b) higher order supported joint engagement that co-occurs with caregiver's follow-in talk (higher order supported joint engagement + follow-in). Follow-in talk occurs when the caregiver talks about objects and events that the child is focused on. Ninety-one autistic children (n = 91) with language delay (mean chronological age = 39 months) participated, along with their primary caregivers. Each of the four variables was measured twice, 8 months apart. Our statistical procedures showed that early higher order supported joint engagement and early higher order supported joint engagement + follow-in were significantly associated with later expressive and receptive vocabulary. In contrast, associations between early vocabulary variables and later joint engagement variables were not significant. Our results suggest that higher order supported joint engagement and higher order supported joint engagement + follow-in may be useful initial intervention targets, for developmental interventions aimed at promoting language development in autistic children who are initially language delayed.

Neurotype-Matching, but Not Being Autistic, Influences Self and Observer Ratings of Interpersonal Rapport

The Double Empathy Problem suggests that communicative difficulties between autistic and non-autistic people are due to bi-directional differences in communicative style and a reciprocal lack of understanding. If true, there should be increased similarity in interaction style, resulting in higher rapport during interactions between pairs of the same neurotype. Here, we provide two empirical tests of rapport, with data revealing whether self- and observer- rated rapport varies depending on the match or mismatch in autism status within a pair. An additional opportunity afforded by these data is to examine the effect of the autism status of the rater on the perceived rapport between matched and mismatched pairs. In Study 1 72 participants were allocated to one of three dyad conditions: autistic pairs (n = 24), non-autistic pairs (n = 24) and mixed pairs (n = 12 autistic; n = 12 non-autistic). Each participant completed three semi-structured interactions with their partner, rating rapport after each interaction. Non-autistic pairs experienced higher self-rated rapport than mixed and autistic pairs, and autistic pairs experienced higher rapport than mixed pairs. In Study 2 (n = 80) autistic and non-autistic observers rated interactional rapport while watching videoed interactions between autistic pairs, non-autistic pairs, and mixed pairs (n = 18, a subset of participants in Study 1). Mixed pairs were rated significantly lower on rapport than autistic and non-autistic pairs, and autistic pairs were rated more highly for rapport than non-autistic pairs. Both autistic and non-autistic observers show similar patterns in how they rate the rapport of autistic, non-autistic, and mixed pairs. In summary, autistic people experience high interactional rapport when interacting with other autistic people, and this is also detected by external observers. Rather than autistic people experiencing low rapport in all contexts, their rapport ratings are influenced by a mismatch of diagnosis. These findings suggest that autistic people possess a distinct mode of social interaction style, rather than demonstrating social skills deficits. These data are considered in terms of their implications for psychological theories of autism, as well as practical impact on educational and clinical practice.

Prediction of social behavior in autism spectrum disorders: Explicit versus implicit social cognition

LAY ABSTRACT

Difficulties with social communication and interaction are a hallmark feature of autism spectrum disorder. These difficulties may be the result of problems with explicit social cognition (effortful and largely conscious processes) such as learning and recalling social norms or rules. Alternatively, social deficits may stem from problems with implicit social cognition (rapid and largely unconscious processes) such as the efficient integration of social information. The goal of this study was to determine how problems in explicit and implicit social cognition relate to social behavior in 34 youth with autism spectrum disorder. We measured aspects of implicit and explicit social cognition abilities in the laboratory using behavioral, cognitive, and brain (electrophysiological) measures. We then used those measures to predict "real-world" social behavior as reported by parents, clinicians, and independent observers. Results showed that overall better aspects of implicit and explicit social cognition predicted more competent social behavior. In addition, the ability to fluidly integrate social information (implicit social cognition) was more frequently related to competent social behavior that merely knowing what to do in social situations (explicit social cognition). These findings may help with the development of interventions focusing on improving social deficits.

Ophthalmological findings in children with autism spectrum disorder

PURPOSE

Eye pathology could be related to atypical visual behaviours and impaired social communication through visual cues in children with autism spectrum disorder (ASD). The main purpose of this prospective study was to assess ophthalmological disorders in children with ASD and to investigate the relationships with intellectual disability (ID) and ASD severity.

METHODS

In this prospective study, comprehensive ophthalmological and oculomotor examinations were performed. ASD severity and verbal and performance intelligence quotients were determined using adapted scales. These clinical data were compared between groups of children based on the presence or absence of ophthalmological disorders and the achievement or not of visual acuity (VA) testing by using non-parametric statistical tests.

RESULTS

Amongst a sample of 51 children, ophthalmological disorders were found in 39% of cases, with 35% having significant refractive errors and 10% presenting with strabismus. Children with ASD and ophthalmological disorders had significantly lower verbal (29.8 ± 14.7 compared with 44.3 ± 21.5; p = 0.010) and performance quotients (57.8 ± 18.3 compared with 67.59 ± 20; p = 0.049) but no significant result was found between the presence of ophthalmological disorders and ASD severity, level of communication and social contact, or modulating behaviour when changes occur. Children who did not achieve monocular VA testing (39%) had significantly lower verbal (25.1 ± 9.7 compared with 46.1 ± 20.9; p < 0.001) and performance quotients (52.7 ± 17 compared with 69.8 ± 18.8; p = 0.001), also presented higher social interaction impairment (p = 0.002), and expressed more important behavioural signs (p = 0.007).

CONCLUSIONS

Ophthalmological disorders are frequently found in children with ASD, especially in those with ID. Ophthalmologists and child psychiatrists should pay attention to perform ophthalmological examination in children with ASD since eye disorders might remain undetected. A comprehensive examination by a paediatric ophthalmologist would help to improve the individual clinical description and the global intervention.

TRIAL REGISTRATION

Clinical trial registration number: NCT02444117.

Temporal Changes in Effect Sizes of Studies Comparing Individuals With and Without Autism: A Meta-analysis

Importance

The definition and nature of autism have been highly debated, as exemplified by several revisions of the DSM (DSM-III, DSM-IIIR, DSM-IV, and DSM-5) criteria. There has recently been a move from a categorical view toward a spectrum-based view. These changes have been accompanied by a steady increase in the prevalence of the condition. Changes in the definition of autism that may increase heterogeneity could affect the results of autism research; specifically, a broadening of the population with autism could result in decreasing effect sizes of group comparison studies.

Objective

To examine the correlation between publication year and effect size of autism-control group comparisons across several domains of published autism neurocognitive research.

Data Sources

This meta-analysis investigated 11 meta-analyses obtained through a systematic search of PubMed for meta-analyses published from January 1, 1966, through January 27, 2019, using the search string autism AND (meta-analysis OR meta-analytic). The last search was conducted on January 27, 2019.

Study Selection

Meta-analyses were included if they tested the significance of group differences between individuals with autism and control individuals on a neurocognitive construct. Meta-analyses were only included if the tested group difference was significant and included data with a span of at least 15 years.

Data Extraction and Synthesis

Data were extracted and analyzed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline using fixed-effects models.

Main Outcomes and Measures

Estimated slope of the correlation between publication year and effect size, controlling for differences in methods, sample size, and study quality.

Results

The 11 meta-analyses included data from a total of 27 723 individuals. Demographic data such as sex and age were not available for the entire data set. Seven different psychological and neurologic constructs were analyzed based on data from these meta-analyses. Downward temporal trends for effect size were found for all constructs (slopes: -0.067 to -0.003), with the trend being significant in 5 of 7 cases: emotion recognition (slope: -0.028 [95% CI, -0.048 to -0.007]), theory of mind (-0.045 [95% CI, -0.066 to -0.024]), planning (-0.067 [95% CI, -0.125 to -0.009]), P3b amplitude (-0.048 [95% CI, -0.093 to -0.004]), and brain size (-0.047 [95% CI, -0.077 to -0.016]). In contrast, 3 analogous constructs in schizophrenia, a condition that is also heterogeneous but with no reported increase in prevalence, did not show a similar trend.

Conclusions and Relevance

The findings suggest that differences between individuals with autism and those without the diagnosis have decreased over time and that possible changes in the definition of autism from a narrowly defined and homogenous population toward an inclusive and heterogeneous population may reduce our capacity to build mechanistic models of the condition.