Neuropsychological profiles of children with agenesis of the corpus callosum: A scoping review.

AIM: To understand the wide variety of clinical outcomes in children with agenesis of the corpus callosum (AgCC) and examine evidence for the proposed neuropsychological syndrome reported in adults with primary AgCC. METHOD: PsycINFO, PsycArticles, Medline, Embase, and Web of Science (January 2007-November 2021) were searched to identify studies reporting on cognitive or neuropsychological outcome in children with AgCC aged up to 18 years. Twenty-three articles investigating the cognitive profile were found; their methodology was evaluated against quality criteria. RESULTS: While there was a high degree of heterogeneity across studies, including the methodological quality, there was evidence for some features of the neuropsychological syndrome in children with AgCC. Vulnerabilities in executive function and social cognition were found, with particular difficulties on complex and novel tasks. INTERPRETATION: Data on the neuropsychological outcomes in children with AgCC are limited. Broad assessments are necessary to determine the extent to which core features of the neuropsychological syndrome may characterize children with AgCC and how additional neuroanatomical features contribute to outcome.

Rethinking the concepts of 'local or global processors': evidence from Williams syndrome, Down syndrome, and Autism Spectrum Disorders.

Both Williams syndrome (WS) and Autism Spectrum Disorder (ASD) have been characterized as preferentially processing local information, whereas in Down syndrome (DS) the reported tendency is to process stimuli globally. We designed a cross-syndrome, cross-task comparison to reveal similarities and differences in local/global processing in these disorders. Our in-depth study compared local/global processing across modalities (auditory-verbal/visuo-spatial) and levels of processing (high/low) in the three syndromes. Despite claims in the literature, participants with ASD or WS failed to show a consistent local processing bias, while those with DS failed to show a reliable global processing bias. Depending on the nature of the stimuli and the task, both local and global processing biases were evident in all three neurodevelopmental disorders. These findings indicate that individuals with neurodevelopmental disorders cannot simply be characterized as local or global processors.

"Hunting with a knife and ... fork": examining central coherence in autism, attention deficit/hyperactivity disorder, and typical development with a linguistic task.

A local processing bias, referred to as "weak central coherence," has been postulated to underlie key aspects of autism spectrum disorder (ASD). Little research has examined whether individual differences in this cognitive style can be found in typical development, independent of intelligence, and how local processing relates to executive control. We present a brief and easy-to-administer test of coherence requiring global sentence completions. We report results from three studies assessing (a) 176 typically developing (TD) 8- to 25-year-olds, (b) individuals with ASD and matched controls, and (c) matched groups with ASD or attention deficit/hyperactivity disorder (ADHD). The results suggest that the Sentence Completion Task can reveal individual differences in cognitive style unrelated to IQ in typical development, that most (but not all) people with ASD show weak coherence on this task, and that performance is not related to inhibitory control. The Sentence Completion Task was found to be a useful test instrument, capable of tapping local processing bias in a range of populations.

An examination of the concept of central coherence in women with anorexia nervosa.

OBJECTIVE: To examine central coherence (local and global processing) in women with anorexia nervosa (AN). METHOD: 42 women with AN and 42 healthy women (HC) completed neuropsychological testing measuring visuospatial and verbal aspects of central coherence: Rey-Osterrieth Complex Figure (RCFT), Embedded Figures Test (EFT), Homograph Reading Test (HRT), and Sentence Completion Task (SCT). RESULTS: People with AN displayed superior performance on the EFT and poorer performance in RCFT with the exception of accuracy in the copy trial. Long hesitations in the SCT were observed. Verbal coherence tasks were not sensitive enough to detect coherence anomalies in AN. CONCLUSION: Women with AN have strengths in tasks requiring local processing (EFT) and weaknesses on tasks benefited by global processing (RCFT and SCT). These results are consistent with the weak central coherence account. This trait might play a role in the maintenance of AN and can be addressed in specific clinical interventions.

Evidence of Reduced Global Processing in Autism Spectrum Disorder.

Frith's original notion of 'weak central coherence' suggested that increased local processing in autism spectrum disorder (ASD) resulted from reduced global processing. More recent accounts have emphasised superior local perception and suggested intact global integration. However, tasks often place local and global processing in direct trade-off, making it difficult to determine whether group differences reflect reduced global processing, increased local processing, or both. We present two measures of global integration in which poor performance could not reflect increased local processing. ASD participants were slower to identify fragmented figures and less sensitive to global geometric impossibility than IQ-matched controls. These findings suggest that reduced global integration comprises one important facet of weak central coherence in ASD.

Canadian Stroke Best Practice Recommendations: Managing transitions of care following Stroke, Guidelines Update 2016.

Every year, approximately 62,000 people with stroke and transient ischemic attack are treated in Canadian hospitals. For patients, families and caregivers, this can be a difficult time of adjustment. The 2016 update of the Canadian Managing Transitions of Care following Stroke guideline is a comprehensive summary of current evidence-based and consensus-based recommendations appropriate for use by clinicians who provide care to patients following stroke across a broad range of settings. The focus of these recommendations is on support, education and skills training for patients, families and caregivers; effective discharge planning; interprofessional communication; adaptation in resuming activities of daily living; and transition to long-term care for patients who are unable to return to or remain at home. Unlike other modules contained in the Canadian Stroke Best Practice Recommendations (such as acute inpatient care), many of these recommendations are based on consensus opinion, or evidence level C, highlighting the absence of conventional evidence (i.e. randomized controlled trials) in this area of stroke care. The quality of care transitions between stages and settings may have a direct impact on patient and family outcomes such as coping, readmissions and functional recovery. While many qualitative and non-controlled studies were reviewed, this gap in evidence combined with the fact that mortality from stoke is decreasing and more people are living with the effects of stroke, underscores the need to channel a portion of available research funds to recovery and adaptation following the acute phase of stroke.

Parent-mediated intervention versus no intervention for infants at high risk of autism: a parallel, single-blind, randomised trial.

BACKGROUND: Risk markers for later autism identified in the first year of life present plausible intervention targets during early development. We aimed to assess the effect of a parent-mediated intervention for infants at high risk of autism on these markers. METHODS: We did a two-site, two-arm assessor-blinded randomised controlled trial of families with an infant at familial high risk of autism aged 7-10 months, testing the adapted Video Interaction to Promote Positive Parenting (iBASIS-VIPP) versus no intervention. Families were randomly assigned to intervention or no intervention groups using a permuted block approach stratified by centre. Assessors, but not families or therapists, were masked to group assignment. The primary outcome was infant attentiveness to parent. Regression analysis was done on an intention-to-treat basis. This trial is registered with ISCRTN Registry, number ISRCTN87373263. FINDINGS: We randomly assigned 54 families between April 11, 2011, and Dec 4, 2012 (28 to intervention, 26 to no intervention). Although CIs sometimes include the null, point estimates suggest that the intervention increased the primary outcome of infant attentiveness to parent (effect size 0.29, 95% CI -0.26 to 0.86, thus including possibilities ranging from a small negative treatment effect to a strongly positive treatment effect). For secondary outcomes, the intervention reduced autism-risk behaviours (0.50, CI -0.15 to 1.08), increased parental non-directiveness (0.81, 0.28 to 1.52), improved attention disengagement (0.48, -0.01 to 1.02), and improved parent-rated infant adaptive function (χ(2)[2] 15.39, p=0.0005). There was a possibility of nil or negative effect in language and responsivity to vowel change (P1: ES-0.62, CI -2.42 to 0.31; P2: -0.29, -1.55 to 0.71). INTERPRETATION: With the exception of the response to vowel change, our study showed positive estimates across a wide range of behavioural and brain function risk-markers and developmental outcomes that are consistent with a moderate intervention effect to reduce the risk for later autism. However, the estimates have wide CIs that include possible nil or small negative effects. The results are encouraging for development and prevention science, but need larger-scale replication to improve precision. FUNDING: Autistica, Waterloo Foundation, Autism Speaks, and the UK Medical Research Council.

Assessing theory of mind nonverbally in those with intellectual disability and ASD: the penny hiding game.

Individuals with autism spectrum disorder (ASD) and low intellectual/language abilities are often omitted from experimental studies because of the challenges of testing these individuals. It is vital to develop appropriate and accessible tasks so that this significant part of the spectrum is not neglected. The theory of mind (ToM) has been extensively assessed in ASD, predominantly in relatively high-functioning individuals with reasonable language skills. This study aims to assess the ToM abilities of a sample of 132 participants with intellectual disability (ID) with and without ASD, matched in verbal mental age (VMA) and chronological age, using a naturalistic and nonverbal deception task: the Penny Hiding Game (PHG). The relationship between performance on the PHG and everyday adaptation was also studied. The PHG proved accessible to most participants, suggesting its suitability for use with individuals with low cognitive skills, attentional problems, and limited language. The ASD + ID group showed significantly more PHG errors, and fewer tricks, than the ID group. PHG performance correlated with Vineland adaptation scores for both groups. VMA was a major predictor of passing the task in both groups, and participants with ASD + ID required, on average, 2 years higher VMA than those with ID only, to achieve the same level of PHG success. VMA moderated the association between PHG performance and real-life social skills for the ASD + ID more than the ID group, suggesting that severely impaired individuals with ASD may rely on verbal ability to overcome their social difficulties, whereas individuals with ID alone may use more intuitive social understanding both in the PHG and everyday situations.

Connectivity and the corpus callosum in autism spectrum conditions: insights from comparison of autism and callosal agenesis.

Neural models of autism spectrum disorders (ASDs) have moved, in recent years, from a lesion model to a focus on abnormal connectivity. In this chapter, we review this work and summarize findings from our recent research comparing autism and agenesis of the corpus callosum (AgCC). We discuss our findings in the context of the "fractionable triad" account and highlight three main points. First, the social aspects of autism can be found in isolation, not accompanied by the nonsocial features of this disorder, supporting a view of autism as a "compound," rather than "monolithic," condition. Second, many young people with callosal agenesis show theory of mind- and emotion-processing deficits akin to those seen in autism. Diagnostic overshadowing may mean these people do not receive interventions that have proven beneficial in ASD. Last, study of AgCC shows that it is possible, in some cases, to develop good social cognitive skills in the absence of the corpus callosum, presenting a challenge to future connectivity models of autism.

The power of the positive: revisiting weak coherence in autism spectrum disorders.

This paper reexamines Frith's original concept of weak coherence, its historical origins, recent reformulations, and alternative accounts. We suggest that the key notion of reduced global integration of information, which Frith proposed to underlie the assets in local processing, has been neglected in recent accounts of autism spectrum disorders (ASD). In fact, most paradigms used to test weak coherence conflate global and local processing, often placing them in direct trade-off, so that it is not possible to tell whether patterns of performance in ASD reflect reduced global processing, increased local processing, or both. We review the literature from typical development and ASD that may be pertinent to this distinction and examine some data from our own studies. Only once tasks are devised that measure separately the effects of reduced global processing and increased local processing will it be possible to test the on-line and developmental relations between these two aspects of "weak coherence". Some preliminary ideas about these relationships are discussed, and suggestions are made for why disentangling two possibly independent dimensions of weak coherence may be timely and productive.

Executive function deficits in autism spectrum disorders and attention-deficit/hyperactivity disorder: examining profiles across domains and ages.

Deficits in 'executive function' (EF) are characteristic of several clinical disorders, most notably Autism Spectrum Disorders (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD). In this study, age- and IQ-matched groups with ASD, ADHD, or typical development (TD) were compared on a battery of EF tasks tapping three core domains: response selection/inhibition, flexibility, and planning/working memory. Relations between EF, age and everyday difficulties (rated by parents and teachers) were also examined. Both clinical groups showed significant EF impairments compared with TD peers. The ADHD group showed greater inhibitory problems on a Go-no-Go task, while the ASD group was significantly worse on response selection/monitoring in a cognitive estimates task. Age-related improvements were clearer in ASD and TD than in ADHD. At older (but not younger) ages, the ASD group outperformed the ADHD group, performing as well as the TD group on many EF measures. EF scores were related to specific aspects of communicative and social adaptation, and negatively correlated with hyperactivity in ASD and TD. Within the present groups, the overall findings suggested less severe and persistent EF deficits in ASD (including Asperger Syndrome) than in ADHD.

Disentangling weak coherence and executive dysfunction: planning drawing in autism and attention-deficit/hyperactivity disorder.

A tendency to focus on details at the expense of configural information, 'weak coherence', has been proposed as a cognitive style in autism. In the present study we tested whether weak coherence might be the result of executive dysfunction, by testing clinical groups known to show deficits on tests of executive control. Boys with autism spectrum disorders (ASD) were compared with age- and intelligence quotient (IQ)-matched boys with attention-deficit/hyperactivity disorder (ADHD), and typically developing (TD) boys, on a drawing task requiring planning for the inclusion of a new element. Weak coherence was measured through analysis of drawing style. In line with the predictions made, the ASD group was more detail-focused in their drawings than were either ADHD or TD boys. The ASD and ADHD groups both showed planning impairments, which were more severe in the former group. Poor planning did not, however, predict detail-focus, and scores on the two aspects of the task were unrelated in the clinical groups. These findings indicate that weak coherence may indeed be a cognitive style specific to autism and unrelated to cognitive deficits in frontal functions.