Autism spectrum disorder: Presentation and prevalence in a nationally representative Australian sample.

OBJECTIVE: The aim of this study was to identify the prevalence of parent-reported autism spectrum disorder diagnosis in Australia, and examine the developmental profile of children with autism spectrum disorder compared to their peers. DESIGN/SETTING: Secondary analyses were undertaken on data from the Longitudinal Study of Australian Children. PARTICIPANTS: Children were recruited at kindergarten (K cohort) and birth (B cohort), and subsequently completed two-yearly 'waves' of assessments. MAIN OUTCOMES: Autism spectrum disorder diagnostic status was ascertained at Wave 4 along with age of diagnosis by parent report. Standardised tools were used to assess children's quality of life, behaviour, receptive vocabulary and non-verbal intelligence. RESULTS: Prevalence of autism spectrum disorder was 2.5% (95% confidence interval = [2.0, 3.0]) in the B cohort compared to 1.5% (95% confidence interval = [1.2, 2.0]) in the K cohort. In both cohorts, children with autism spectrum disorder had poorer mean quality of life, emotional-behavioural functioning and receptive vocabulary compared with non-autism spectrum disorder peers, and a higher proportion of children with autism spectrum disorder had problems in these areas. However, between 6% and 9% of children with moderate to severe autism spectrum disorder and 12-20% with mild autism spectrum disorder were not reported to have problems with social interaction. CONCLUSION: The prevalence of a parent-reported diagnosis of autism spectrum disorder before age 7 in Australia was higher in the B cohort. Data from future Longitudinal Study of Australian Children waves will clarify whether autism spectrum disorder has been diagnosed earlier in the B cohort or if there is a continued increase in prevalence. Future waves will also provide crucial information about the types and severity of problems experienced during the primary and secondary school years which will assist service planning.

Crossing roads safely: an experimental study of age differences in gap selection by pedestrians.

The over-representation of older pedestrians in serious injury and fatal crashes compared to younger adults may be due, in part, to age-related diminished ability to select gaps in oncoming traffic for safe road-crossing. Two experiments are described that examine age differences in gap selection decisions in a simulated road-crossing environment. Three groups of participants were tested, younger (30-45 years), young-old (60-69 years) and old-old (>75 years). The results showed that, for all age groups, gap selection was primarily based on vehicle distance and less so on time-of-arrival. Despite the apparent ability to process the distance and speed of oncoming traffic when given enough time to do so, many of the old-old adults appeared to select insufficiently large gaps. These results are discussed in terms of age-related physical, perceptual and cognitive limitations and the ability to compensate for these limitations. Practical implications for road safety countermeasures are also highlighted, particularly the provision of safe road environments and development of behavioural and training packages.