Autism spectrum disorder

According to DSM-5 (2014):

1. Impairments in social-emotional reciprocity, ranging, for example, from abnormal social approach and failure of normal two-way conversation through impairment in shared interests, emotions, or affect to failure to initiate or respond to social interactions.
2. Deficits in non-verbal communicative behaviours used in social interaction range, for example, from poorly integrated verbal and non-verbal communication through abnormalities of eye contact and body language or deficits in understanding and use of gestures, to a complete lack of facial expression and non-verbal communication.
3. Impairments in the development, maintenance and understanding of relationships range, for example, from difficulties in adjusting behaviour in various social contexts through difficulties in sharing imaginative play or making friends, to a lack of interest in other people.

Restrictive and repetitive patterns of behaviour, interests or activities:

1. Stereotyped or repetitive movements, use of objects or speech (e.g. simple motor stereotypies, lining up toys or rearranging objects, echolalia, idiosyncratic phrases).
2. Insistence on monotony, excessive inflexibility of routines or ritualised patterns of verbal or non-verbal behaviour (e.g. great distress at small changes, difficulties with transitions, rigid thought patterns, greeting rituals, need to take the same route or eat the same food every day).
3. Very restricted and fixed interests that are abnormal in intensity or focus of interest (e.g. strong attachment or preoccupation with unusual objects, excessively circumscribed or perseverative interests).
4. Hyper- or hypo-reactivity to sensory stimuli or unusual interest in sensory aspects of the environment (e.g., apparent indifference to pain/temperature, adverse response to specific sounds or textures, excessive sniffing or touching of objects, visual fascination with lights or movement).

Other features:

1. Symptoms must be present early in the developmental period (but may not fully manifest until social demand exceeds limited capacities, or may be masked by strategies learned later in life).
2. Symptoms cause clinically significant impairment in social, occupational or other important areas of usual functioning.
3. These impairments are not best explained by intellectual disability (intellectual developmental disorder) or global developmental delay. Intellectual disability and autism spectrum disorder often overlap; to make co-morbid diagnoses of autism spectrum disorder and intellectual disability, social communication must be below that expected for the general level of development.

> American Psychiatric Association (2014). Diagnostic and Statistical Manual of Mental Disorders (DSM-5), 5th Ed.