Memory in autism spectrum disorder: a meta-analysis of experimental studies

To address inconsistencies in the literature on memory in Autism Spectrum Disorder (ASD), we report the first ever meta-analysis of short-term (STM) and episodic long-term (LTM) memory in ASD, evaluating the effects of type of material, type of retrieval and the role of inter-item relations. Analysis of 64 studies comparing individuals with ASD and typical development (TD) showed greater difficulties in ASD compared to TD individuals in STM (Hedges’ g=-0.53 [95%CI -0.90; -0.16], p=.005, I²=96%) compared to LTM (g=-0.30 [95%CI -0.42; -0.17], p<.00001, I²=24%), a small difficulty in verbal LTM (g=-0.21, p=.01), contrasting with a medium difficulty for visual LTM (g= -0.41, p=.0002) in ASD compared to TD individuals. We also found a general diminution in free recall compared to cued recall and recognition (LTM, free recall: g=-0.38, p<.00001, cued recall: g=-0.08, p=.58, recognition: g=-0.15, p=.16; STM, free recall: g=-0.59, p=.004, recognition: g=-0.33, p=.07). We discuss these results in terms of their relation to semantic memory. The limited diminution in verbal LTM and preserved overall recognition and cued recall (supported retrieval) may result from a greater overlap of these tasks with semantic long-term representations which are overall preserved in ASD. By contrast, difficulties in STM or free recall may result from less overlap with the semantic system or may involve additional cognitive operations and executive demands. These findings highlight the need to support STM functioning in ASD and acknowledge the potential benefit of using verbal materials at encoding and broader forms of memory support at retrieval to enhance performance

Autistic symptomatology and language ability in Autism Spectrum Disorder and Specific Language Impairment

Background: Autism spectrum disorders (ASD) and specific language impairment (SLI) are common developmental disorders characterised by deficits in language and communication. The nature of the relationship between them continues to be a matter of debate. This study investigates whether the co-occurrence of ASD and language impairment is associated with differences in severity or pattern of autistic symptomatology or language profile. Methods: Participants (N = 97) were drawn from a total population cohort of 56,946 screened as part of study to ascertain the prevalence of ASD, aged 9 to 14 years. All children received an ICD-10 clinical diagnosis of ASD or No ASD. Children with nonverbal IQ 80 were divided into those with a language impairment (language score of 77 or less) and those without, creating three groups: children with ASD and a language impairment (ALI; N = 41), those with ASD and but no language impairment (ANL; N = 31) and those with language impairment but no ASD (SLI; N = 25). Results: Children with ALI did not show more current autistic symptoms than those with ANL. Children with SLI were well below the threshold for ASD. Their social adaptation was higher than the ASD groups, but still nearly 2 SD below average. In ALI the combination of ASD and language impairment was associated with weaker functional communication and more severe receptive language difficulties than those found in SLI. Receptive and expressive language were equally impaired in ALI, whereas in SLI receptive language was stronger than expressive. Conclusions: Co-occurrence of ASD and language impairment is not associated with increased current autistic symptomatology but appears to be associated with greater impairment in receptive language and functional communication

The Comorbidity of ADHD and Autism Spectrum Disorders (ASDs) in Community Preschoolers

Symptoms of inattention and hyperactivity, features of attention-deficit/hyperactivity disorder (ADHD), have been frequently documented in children with autism spectrum disorders (ASDs) and often co-occur. Evidence indicates that 20-50% of children with ADHD meet criteria for ASD, and 30-80% of ASD children meet criteria for ADHD

Psychopathology in Down Syndrome

The main aim of this section is to provide clinicians with a guide to the prevalence of psychopathologies, associated factors, and their treatment in children with Down syndrome (DS). Attention-deficit/hyperactivity disorder (ADHD), behavioral disorders, depression, and autism are more common in DS than the normal population. However, the incidence of psychopathology is generally lower in DS than in other diseases that cause mental retardation. While writing this chapter, approximately 200 articles in electronic databases were scanned using the keywords “Down Syndrome and Psychopathology,” “Down Syndrome and Mood Disorder,” “Down Syndrome and Autism,” “Down Syndrome and Anxiety,” “Down Syndrome and Catatonia,” and “Down Syndrome and Behavioral Disorder.” Psychopathologies in DS will be presented in eight subtitles beginning with the most often diagnosed. It is important to perform psychological evaluations of patients with DS during routine follow-ups. Comorbid diseases (obstructive sleep apnea, cardiac pathologies, etc.) should be taken into account when choosing drugs

Visuo-perceptual correlates of autistic trait expression in children with Fragile X syndrome and Down Syndrome

Autism Spectrum Disorder (ASD) is a clinical umbrella term used to reference a neurodevelopmental profile of socio-communicative impairment and restricted, repetitive patterns of behaviour (RRB). In most cases, ASD is ‘idiopathic’ meaning that genetic aetiology is poorly defined. In other cases, ASD may present in genetic syndrome groups of known aetiology, like Fragile X syndrome (FXS) and Down syndrome (DS). There is research to suggest that these ‘syndromic’ forms of ASD manifest distinctly in terms of behavioural symptomatology; however, beyond this level of description, we know little of the nature of these comorbidities. Visuo-perceptual irregularities are well documented in idiopathic ASD populations; in particular, spatial orienting and visual search abilities are known to be affected. Prior to this doctorate research, it remained to be seen whether behavioural manifestations of autistic-like impairment in FXS and DS were characterised by similar visuo-perceptual abnormalities. This thesis presents a series of eye-tracking studies designed to characterise syndromic forms of ASD according to associated visuo-perceptual mechanism. The work that is presented here examines the visuo-perceptual correlates of autistic trait expression in neuro-typical (NT) children (n=56) and in three clinical paediatric cohorts: idiopathic ASD (n=16), FXS (n=7) and DS (n=15), focusing specifically on attentional disengagement and visual search performance. The results are consistent with the notion of syndrome-specific profiles of autistic-like impairment, extending the literature and elucidating the complex heterogeneity that is associated with ASD. Moreover, they illustrate the value of progressing beyond superficial behavioural indices of autistic-like impairment to examine, in a more fine-grained way, the neurocognitive features underpinning comorbid expressions of autistic-like deficit

The cerebellum and divided attention in autism spectrum disorders

textDivided attention, or the ability to respond to more than one task simultaneously, is an important skill for navigating complex social, communicative, academic, and professional settings. The purpose of the current study was to understand the association between the volume of the posterior cerebellum and divided attention in individuals with autism spectrum disorders (ASDs) and control participants. It was hypothesized that the ASD group would have worse divided attention abilities and smaller posterior cerebellar volumes compared to the control group. Furthermore, reduced posterior cerebellar volume was expected to be associated with weaker divided attention abilities. Participants were young adult males with high-functioning autism spectrum disorders (n=15) and controls matched for age, handedness, and nonverbal IQ (n=19). Results showed partial support for worse divided attention performance in ASDs and for a positive association between posterior cerebellar volume and divided attention performance. There were no group differences in posterior cerebellar volume, and accounting for intracranial volume did not affect findings. Limitations of the current study and future directions are discussed.Educational Psycholog

Low birthweight and preterm birth in young people with special educational needs: a magnetic resonance imaging analysis

<p>Abstract</p> <p>Background</p> <p>Although neuroanatomical and cognitive sequelae of low birthweight and preterm birth have been investigated, little is understood as to the likely prevalence of a history of low birthweight or preterm birth, or neuroanatomical correlates of such a history, within the special educational needs population. Our aim was to address these issues in a sample of young people receiving additional learning support.</p> <p>Methods</p> <p>One hundred and thirty-seven participants aged 13–22 years, receiving additional learning support, were recruited via their schools or colleges and underwent structural magnetic resonance imaging (MRI). Obstetric records, available in 98 cases, included birthweight and gestational data in 90 and 95 cases, respectively. Both qualitative and quantitative voxel-based analyses of MRI data were conducted.</p> <p>Results</p> <p>A history of low birthweight and preterm birth was present in 13.3% and 13.7% of cases, respectively. Low birthweight and preterm birth were associated with specific qualitative anomalies, including enlargement of subarachnoid cisterns and thinning of the corpus callosum. Low birthweight was associated with reduced grey matter density (GMD) in the superior temporal gyrus (STG) bilaterally, left inferior temporal gyrus and left insula. Prematurity of birth was associated with reduced GMD in the STG bilaterally, right inferior frontal gyrus and left cerebellar hemisphere. Comparison of subjects with no history of low birthweight or preterm birth with a previously defined control sample of cognitively unimpaired adolescents (<it>n </it>= 72) demonstrated significantly greater scores for several anomalies, including thinning of the corpus callosum, loss of white matter and abnormalities of shape of the lateral ventricles.</p> <p>Conclusion</p> <p>Although a two-fold increased prevalence of a history of low birthweight and preterm birth exists within the special educational needs population, other aetiological factors must be considered for the overwhelming majority of cases. Neuroanatomical findings within this sample include qualitative anomalies of brain structure and grey matter deficits within temporal lobe structures and the cerebellum that persist into adolescence. These findings suggest a neurodevelopmental mechanism for the cognitive difficulties associated with these obstetric risk factors.</p

Behavioural outcomes and psychopathology during adolescence

Preterm birth is associated with a high risk of residual neurodevelopmental disability and cognitive impairment. These problems are closely associated with psychiatric disorders and thus it is unsurprising that preterm birth also confers high risk for poor long term mental health. The risk associated with preterm birth is not a general one, but appears to be specific to symptoms and disorders associated with anxiety, inattention and social and communication problems, and manifest in a significantly higher prevalence of emotional disorders, ADHD and Autism. Adolescence is a key period for mental health and studies have shown that problems evident in childhood persist over this time and are more stable amongst preterm individuals than term-born peers. There is also modest evidence for an increased prevalence of psychotic symptoms in preterm adolescents. The high prevalence of psychiatric disorders, present in around 25% of preterm adolescents, requires long term screening and intervention

Atypical eye contact in autism: Models, mechanisms and development

An atypical pattern of eye contact behaviour is one of the most significant symptoms of Autism Spectrum Disorder (ASD). Recent empirical advances have revealed the developmental, cognitive and neural basis of atypical eye contact behaviour in ASD. We review different models and advance a new ‘fast-track modulator model’. Specifically, we propose that atypical eye contact processing in ASD originates in the lack of influence from a subcortical face and eye contact detection route, which is hypothesized to modulate eye contact processing and guide its emergent specialization during development