The Checklist for Autism in Toddlers is a short questionnaire which is filled out by the parents and a primary health care worker at the 18 month developmental check up. It aims to identify children who are risk for social-communication disorders.

The CHAT can be found attached. It consists of two sections: the first nine items are questions asked to the parents, and the last five items are observations made by the primary health care worker. The key items look at behaviors which, if absent at 18 months, put a child at risk for a social-communication disorder.  These behaviors are (a) joint attention, including pointing to show and gaze-monitoring ( e.g. looking to where a parent is pointing), and (b) pretend play (e.g. pretending to pour tea form a toy teapot).

The CHAT is very easy to score. There are 5 key items: A5 (pretend play), A7 (proto declarative pointing), Bii (following a point), Biii (pretending) and Biv (producing a point). If a child fails all 5 key items, they have a high risk of developing autism. Children who fail items A7 and Biv have a medium risk of developing autism.

Any child who fails the CHAT should be re-screened approximately one month later. As with any screening instrument, a second CHAT is advisable so that those children who are just slightly delayed are given time to catch up and also to focus efforts on children who are failing consistently. Any child who fails the CHAT for a second time should be referred to a specialist clinic for diagnosis since the CHAT is not a diagnostic tool.

If a child passes the CHAT during the administration, no further action needs to be taken. However, passing the CHAT does not guarantee that a child will not go on to develop a social-communication problem of some form and if parents are worried they should see referral.

Because there is no single known medical cause of social-communication disorder, it is very unlikely that there will be a medical test available in the near future. Whatever the cause of these problems, the behavioral characteristics have been identified and this is what the CHAT is based on. In addition, the CHAT is cheap, quick and easy to administer.