Diagnostic Criteria of Autism

Autism has almost certainly always existed. However, autism was not recognized as a distinct condition until the mid twentieth century.
For a diagnosis of autism, behavior must be significantly impaired in two major ways. Below are four criteria that must be met for a diagnosis of autism.

1. Persistent deficits in social communication and social interaction across multiple contexts.

• deficits in social emotional reciprocity, ranging from abnormal social approach and failure of normal back and forth conversation to reduced sharing of interest, emotions, or failure to initiate or respond to social interactions.
• deficits in nonverbal communicative behaviors used for social interaction raging from poorly integrated verbal and nonverbal communication, to abnormalities in eye contact and body language or deficits in understanding and use of gestures
• deficits in developing, maintaining, and understanding relationships

2. Restricted, repetitive patterns of behavior interest, or activities as manifested by at least two of the following

• stereotyped or repetitive speech, motor movements, or use of objects
• excessive adherences to routines, ritualized patterns of verbal and nonverbal behavior or excessive resistance to change
• highly restricted, fixated interest that are abnormal in intensity or focus
• hyper or hypo reactivity to sensory input

3. Symptoms must be present in early childhood

4. Symptoms together limit and impair everyday functioning

Then, there is an evaluation of descriptors which is the severity level and specifiers.

Severity of socio-communicative impairements

Level 1-requiring support- without supports in place, deficits in social communication causes noticeable impairments, has difficulty initiating social interactions and demonstrates clear examples of atypical or unsuccessful responses to social overtures of others.

Level 2- requiring substantial support- marked deficits in verbal and nonverbal social communication skills, social impairments apparent even with supports in place, limited initiations of social interactions and reduced or abnormal response to social overtures from others. 

Level 3- requires very substantial support- severe deficits in verbal and nonverbal social communication skills cause severe impairments in functioning. , very limited initiation of social interactions and minimal response to social overtures from others.

Severity of restricted, repetitive behaviors

Level 1- requiring support, cause significant interference with functioning in one or more contexts

Level 2- requiring substantial support, preoccupations or fixated interest appear frequently enough to be obvious to the causal observer and interfere with functioning in a variety of contexts

Level 3-requiring very substantial support, fixated rituals and repetitive behaviors markedly interfere with functioning in all spheres.