Table 1.

ASD symptoms and signs*

• ASD symptoms must be present in the early developmental period (but might not become fully manifest until social demands exceed limited capacities, or might be masked by learned strategies in later life).

• Symptoms in the social communication/interaction must include impairments in

- Social emotional reciprocity (e.g. failure of normal back and forth conversation; or reduced sharing of interests, emotions, or affection)

- Non-verbal communicative behaviours (e.g. abnormalities in eye contact and body language)

- Developing, maintaining, and understanding relationships (e.g. difficulties in sharing imaginative play or making friends).

• Symptoms in the repetitive patterns of behaviour must include impairments in two of

- Stereotyped or repetitive motor movements, use of objects or speech (e.g. lining up toys, or flipping objects)

- Insistence on sameness, inflexible adherence to routines or ritualised patterns of verbal and non-verbal behaviour (e.g. extreme distress at small changes, difficulties with transitions or rigid thinking patterns)

- Highly restricted, fixated interests that are abnormal in intensity or focus (e.g. strong attachment to or preoccupation with unusual objects)

- Hyper-reactivity or hypo-reactivity to sensory input, or unusual interests in sensory aspects of the environment (e.g. apparent indifference to pain or temperature, or adverse responses to specific sounds or textures).

*Developed from information in Diagnostic and Statistical Manual of Mental Disorders [2]