Autism currently remains a diagnosis based exclusively on observed behaviours and analysis of developmental history. Although various early diagnostic markers have been put forward as potential candidates to make the diagnostic process more objective and onwards remove the subjectivity behind making a diagnosis, none have so far lived up to expectation.
Part of the reason for the desire for early biomarkers rests on the perceived effectiveness of early intervention, very early intervention, and how a universal biological or genetic marker would inevitably further inform about the aetiology of autism.
The notion of an objective marker for autism is however complicated. Not only because of the heterogeneity which exists with regards to the presentation of autism, but also following moves to classify autism as a more plural condition (‘the autisms’), the growing interest in the process of regression in cases of autism and the complicating factor of comorbidity which often follows a diagnosis of autism. That also the presentation of autism may be prone to some instability during the early years of development and beyond is also another interfering variable.
The paper by Hedvall and colleagues* adds to a growing volume of research literature suggesting that the presentation of autism in the preschool years may be surprisingly unstable; urging caution when it comes to drawing too many conclusions about the nature of autism in early infancy. Based on observations of 208 preschool children with various types of diagnosis/presentation included under the autism spectrum umbrella, researchers charted the developmental trajectories of participants over two years. They looked at the presentation of autism symptoms as well as other important factors such as the presence of intellectual disability.
Their results suggested that the presentation of autism and associated developmental skills during this important early developmental period was a surprisingly fluid process. In particular, around half of children at the follow-up point were reported to present with some degree of intellectual disability, mostly severe intellectual disability alongside their autism. This contrasted sharply with little or no mention of such issues at first diagnostic encounter.
On that basis, researchers conclude that assessments made later in childhood, prior to the start of school, may offer a more reliable picture of the presentation of autism and associated issues compared with an earlier preschool assessment.
Further work is required on this topic area to further confirm how much and for whom stability might be an issue when it comes to the presentation of autism and associated issues. Whether such findings also translate into biological or genetic expression changes as a function of maturation is as yet unknown, as is the relative contribution of any early intervention measures which participants may have been following during the interval period. What is clear is that autism is a dynamic condition; and outside a need to show how autism ages with a person, the early days presentation of autism remains an important research topic.
* Hedvall A. et al. Autism and developmental profiles in preschoolers: stability and change over time. Acta Paediatr. 2013 Oct 8. doi: 10.1111/apa.12455.
Further commentary on this study can be found at: http://questioning-answers.blogspot.com/2013/12/autism-and-changing-preschool-developmental-profile.html