Attentional allocation of autism spectrum disorder individuals: Searching for a Face-in-the-Crowd.

A study is reported which tests the proposition that faces capture the attention of those with autism spectrum disorders less than a typical population. A visual search task based on the Face-in-the-Crowd paradigm was used to examine the attentional allocation of autism spectrum disorder adults for faces. Participants were required to search for discrepant target images from within 9-image arrays. Both participants with autism spectrum disorder and control participants demonstrated speeded identification of faces compared to non-face objects. This indicates that when attention is under conscious control, both autism spectrum disorder and typically developing comparison adults show an attentional bias for faces, which contrasts with previous research which found an absence of an attentional bias for faces in autism spectrum disorder. Theoretical implications of this differentiation are discussed.

The longitudinal development of social and executive functions in late adolescence and early adulthood.

Our earlier work suggests that, executive functions and social cognition show protracted development into late adolescence and early adulthood (Taylor et al., 2013). However, it remains unknown whether these functions develop linearly or non-linearly corresponding to dynamic changes to white matter density at these age ranges. Executive functions are particularly in demand during the transition to independence and autonomy associated with this age range (Ahmed and Miller, 2011). Previous research examining executive function (Romine and Reynolds, 2005) and social cognition (Dumontheil et al., 2010a) in late adolescence has utilized a cross sectional design. The current study employed a longitudinal design with 58 participants aged 17, 18, and 19 years completing social cognition and executive function tasks, Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999), Positive and Negative Affect Schedule (Watson et al., 1988), and Hospital Anxiety and Depression Scale (Zigmond and Snaith, 1983) at Time 1 with follow up testing 12-16 months later. Inhibition, rule detection, strategy generation and planning executive functions and emotion recognition with dynamic stimuli showed longitudinal development between time points. Self-report empathy and emotion recognition functions using visual static and auditory stimuli were stable by age 17 whereas concept formation declined between time points. The protracted development of some functions may reflect continued brain maturation into late adolescence and early adulthood including synaptic pruning (Sowell et al., 2001) and changes to functional connectivity (Stevens et al., 2007) and/or environmental change. Clinical implications, such as assessing the effectiveness of rehabilitation following Head Injury, are discussed.

The typical developmental trajectory of social and executive functions in late adolescence and early adulthood.

Executive functions and social cognition develop through childhood into adolescence and early adulthood and are important for adaptive goal-oriented behavior (Apperly, Samson, & Humphreys, 2009; Blakemore & Choudhury, 2006). These functions are attributed to frontal networks known to undergo protracted maturation into early adulthood (Barker, Andrade, Morton, Romanowski, & Bowles, 2010; Lebel, Walker, Leemans, Phillips, & Beaulieu, 2008), although social cognition functions are also associated with widely distributed networks. Previously, nonlinear development has been reported around puberty on an emotion match-to-sample task (McGivern, Andersen, Byrd, Mutter, & Reilly, 2002) and for IQ in midadolescence (Ramsden et al., 2011). However, there are currently little data on the typical development of social and executive functions in late adolescence and early adulthood. In a cross-sectional design, 98 participants completed tests of social cognition and executive function, Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999), Positive and Negative Affect Schedule (Watson, Clark, & Tellegen, 1988), Hospital Anxiety and Depression Scale (Zigmond & Snaith, 1983), and measures of pubertal development and demographics at ages 17, 18, and 19. Nonlinear age differences for letter fluency and concept formation executive functions were found, with a trough in functional ability in 18-year-olds compared with other groups. There were no age group differences on social cognition measures. Gender accounted for differences on 1 scale of concept formation, 1 dynamic social interaction scale, and 2 empathy scales. The clinical, developmental, and educational implications of these findings are discussed.

The structure of savant calendrical knowledge.

AIM: We aimed to explore the organization of the calendar knowledge base underlying date calculation by assessing the ability of savant calendar calculators to free recall a series of date lists. METHOD: Four experiments are reported that assessed recall of structural and non-structural features of the calendar in eight savant calendar calculators (seven males; one female; median age 34 y 6 mo; age range 27-47 y), five of whom had a diagnosis on the autism spectrum. The inclusion criterion was a genuine calculation ability rather than an interest in dates. RESULTS: Mean recall was facilitated for material organized according to the structural features of a calendar (leap years, dates falling on the same weekday, dates occurring at 28 y intervals) but not for a non-structural calendar feature (Easter Sunday). INTERPRETATION: Distinctions are drawn between two sources of savant calendar-related knowledge, structural and event related. It has been suggested that structural knowledge plays a key role in the acquisition and operation of savant date calculation skills.

Attentional processing of faces in ASD: a Dot-Probe study.

The present study used the Dot-Probe paradigm to explore attentional allocation to faces compared with non-social images in high-functioning individuals with autism spectrum disorder (ASD) and typically developing controls. There was no evidence of attentional bias in either group when stimuli were presented at individually calculated sub-threshold levels. However, at supra-threshold presentation (200 ms), a face bias was found for control participants but not for those with ASD. These results add to evidence of reduced social interest in ASD, relative to controls, and further demonstrate when atypical social processing arises in the attentional time course.

Rate of first recorded diagnosis of autism and other pervasive developmental disorders in United Kingdom general practice, 1988 to 2001.

BACKGROUND: There has been concern that the incidence of autism and other pervasive developmental disorders (PDDs) is increasing. Previous studies have been smaller, restricted to autism (excluding other pervasive developmental disorders such as Asperger's syndrome), included boys only, or have not been based on a national sample. We investigated time trends in the rates of diagnosis of pervasive developmental disorders. METHODS: We analysed the rates of first diagnosis of pervasive developmental disorders among people registered with a practice contributing to the United Kingdom General Practice Research Database during the period 1988 to 2001. We included 1410 cases from over 14 million person-years of observation. The main outcome measures were rates of diagnosis of pervasive developmental disorders by year of diagnosis, year of birth, gender and geographical region. RESULTS: The rate increased progressively from 0.40/10,000 person-years (95% CI 0.30 to 0.54) in 1991 to 2.98/10,000 (95% CI 2.56 to 3.47) in 2001. A similar change occurred in the age standardised incidence ratios, from 35 (95% CI: 26-47) in 1991 to 365 (95% CI: 314-425) in 2001. The temporal increase was not limited to children born during specific years nor to children diagnosed in a specific time period. The rate of diagnosis of PDDs other than autism rose from zero for the period 1988-1992 to 1.06/10,000 person-years in 2001. The rate of diagnosis of autism also increased but to a lesser extent. There was marked geographical variation in rates, with standardised incidence ratios varying from 66 for Wales to 141 for the South East of England. CONCLUSIONS: Better ascertainment of diagnosis is likely to have contributed to the observed temporal increase in rates of diagnosis of PDD, but we cannot exclude a real increase.

MMR vaccination and pervasive developmental disorders: a case-control study.

BACKGROUND: Concern that measles-mumps-rubella (MMR) vaccination might cause autism has led to a fall in vaccine coverage. We investigated whether MMR vaccination is associated with an increased risk of autism or other pervasive developmental disorders. METHODS: We did a matched case-control study using the UK General Practice Research Database. Cases were people born in 1973 or later who had first recorded diagnosis of pervasive developmental disorder while registered with a contributing general practice between 1987 and 2001. Controls were matched on age, sex, and general practice. FINDINGS: 1294 cases and 4469 controls were included. 1010 cases (78.1%) had MMR vaccination recorded before diagnosis, compared with 3671 controls (82.1%) before the age at which their matched case was diagnosed. After adjustment for age at joining the database, the odds ratio for association between MMR and pervasive developmental disorder was 0.86 (95% CI 0.68-1.09). Findings were similar when restricted to children with a diagnosis of autism, to those vaccinated with MMR before the third birthday, or to the period before media coverage of the hypothesis linking MMR with autism. INTERPRETATION: Our findings suggest that MMR vaccination is not associated with an increased risk of pervasive developmental disorders.

Validation of the diagnosis of autism in general practitioner records.

BACKGROUND: We report on the validity of the computerized diagnoses of autism in a large case-control study investigating the possible association between autism and the measles, mumps and rubella vaccine in the UK using the General Practitioner Research Database (GPRD). We examined anonymized copies of all relevant available clinical reports, including general practitioners' (GP) notes, consultant, speech therapy and educational psychologists reports, on 318 subjects born between 1973 and 1997 with a diagnosis of autism or a related disorder recorded in their electronic general practice record. METHODS: Data were abstracted to a case validation form allowing for the identification of developmental symptoms relevant to the diagnosis of pervasive developmental disorders (PDDs). Information on other background clinical and familial features was also abstracted. A subset of 50 notes was coded independently by 2 raters to derive reliability estimates for key clinical characteristics. RESULTS: For 294 subjects (92.5%) the diagnosis of PDD was confirmed after review of the records. Of these, 180 subjects (61.2%) fulfilled criteria for autistic disorder. The mean age at first recording of a PDD diagnosis in the GPRD database was 6.3 years (SD = 4.6). Consistent with previous estimates, the proportion of subjects experiencing regression in the course of their development was 19%. Inter-rater reliability for the presence of a PDD diagnosis was good (kappa =.73), and agreement on clinical features such as regression, age of parental recognition of first symptoms, language delay and presence of epilepsy was also good (kappas ranging from.56 to 1.0). CONCLUSIONS: This study provides evidence that the positive predictive value of a diagnosis of autism recorded in the GPRD is high.