Autism prodrome 16 of 89
of age some aspects of the beginnings of play; emotional responsiveness, sensory
behaviors and social engagement might be present in at least some children. However,
at this earlier age compared to the CHAT study (14 vs. 18 months) these early signs
appear to be less specific to ASD, identifying almost as many children who went on
have LD and ID. This and other studies cannot report on the sensitivity of these signs
to all cases of ASD until a population follow up of the whole sample has been
conducted to identify missed cases.
A number of other groups have also developed and begun to test screens for
ASDs both in total population samples and in clinically referred samples. Robins et al.
(2001) developed a modified version of the CHAT (the M-CHAT) that included
additional items measuring other aspects of early social communication impairments
characteristic of autism (e.g. response to name, imitation) as well as repetitive
behaviors (e.g. unusual fingers mannerisms) and sensory abnormalities (e.g.
oversensitivity to noise). The M-CHAT is a parent report instrument and the health
practitioner does no direct testing. In their initial report, Robins et al. (2001) had
tested 1,122 unselected children (initially at 18 months but subsequently at 24 months
of age) and 171 children referred for early intervention services (considered to be at
high risk of having an ASD or other developmental disability). The screen (initially
with 30 items, subsequently reduced to 23 items) was completed independently by
parents of children seen by pediatricians in the unselected sample and seen by early
intervention service providers in the referred sample. Following analysis of the first
600 returns, a cut-off was set as failing 2 from 8 'critical items' or any 3 items from
the total of 23 items (Robins et al., 2001). Once a child failed the M-CHAT the
research team re-administered the screen by telephone and if a child still scored above
cut-off the family was invited for an assessment.