Another day, another interesting study. This time researchers looked at home video recording of children with autism and attempted to determine what the onset of autism looked like. They found that there appeared to be three separate tracks of development - from birth, regression, and plateau.
This result is similar to another study from last year. But in that study, children who went on to develop autism were found to be virtually indistinguishable from the peers until sometime between the 6 to 18 month mark and suggested that most cases of autism were a combination of plateau and regressive.
I haven't read the current study text (yet) but I think one of the differences between these two studies is that the current one seems to be looking backward using existing video snippets while the earlier one actually evaluated the children numerous times as they aged.
It is easy to look at a video clip knowing that a child has autism and see "signs" of what could be autism when it could equally be an off day or non-typical behavior. I am not saying that the current study did that but it is always a hazard of relying on video. Although the current study does have an awful lot of clips so maybe the clips were done on a regularly planned interval.
The study does have a good point about parents being able to properly recall their children's development. It is hard to remember what exactly a child was or was not doing at a specific point in time years later. Although then again, equating parental answers on the ADI-R to actual parental recall of development might not be completely valid.
Onset patterns in autism: correspondence between home video and parent report.
J Am Acad Child Adolesc Psychiatry. 2011 Aug;50(8):796-806.e1. Epub 2011 Jun 2.
Ozonoff S, Iosif AM, Young GS, Hepburn S, Thompson M, Colombi C, Cook IC, Werner E, Goldring S, Baguio F, Rogers SJ.
University of California-Davis.
The onset of autism is usually conceptualized as occurring in one of two patterns, early onset or regressive. This study examined the number and shape of trajectories of symptom onset evident in coded home movies of children with autism and examined their correspondence with parent report of onset.
Four social-communicative behaviors were coded from the home video of children with autism (n = 52) or typical development (n = 23). All home videos from 6 through 24 months of age were coded (3199 segments). Latent class modeling was used to characterize trajectories and determine the optimal number needed to describe the coded home video. These trajectories were then compared with parent reports of onset patterns, as defined by the Autism Diagnostic Interview-Revised.
A three-trajectory model best fit the data from the participants with autism. One trajectory displayed low levels of social-communication across time. A second trajectory displayed high levels of social-communication early in life, followed by a significant decrease over time. A third trajectory displayed initial levels of behavior that were similar to the typically developing group but little progress in social-communication with age. There was poor correspondence between home video-based trajectories and parent report of onset.
More than two onset categories may be needed to describe the ways in which symptoms emerge in children with autism. There is low agreement between parent report and home video, suggesting that methods for improving parent report of early development must be developed.