While psychiatry traditionally classifies autism as a neurodevelopmental disorder, many autistic people, most autistic advocates and a rapidly increasing number of researchers see autism as part of neurodiversity, the natural diversity in human thinking, and experience, with strengths, differences, and weaknesses. On this view, promoted by the autism rights movement, autism is not pathological, but this does not preclude autistic individuals from being disabled and potentially having high support needs due to co-occurring conditions and lack of person-environment fit. This relatively positive and holistic view of autism has led to a certain degree of friction between autistic individuals, advocates, charities, researchers and practitioners.The causes of autism are not well understood, but are likely linked to altered structures of the brain at birth. There is no official cure for autism, so interventions focus on, for example, finding and learning other modes of communication in a non-verbal autist, or applied behavior analysis interventions, which are highly controversial. Other controversies in autism are scientific, sociological, political, or philosophical, and some have aspects of all four. First, it is controversial and uncertain if social-communication difficulties of autistic people are inherent core deficits (see empathizing-systemizing theory developed by Simon Baron-Cohen), or due to mismatch in social communication styles, cognition, and experiences resulting in bidirectional misunderstanding between autistic people and non-autistic people (see double empathy problem theory developed by autistic researcher Damien Milton and recent growing evidence that found that autistic people empathize, communicate and socialize well with autistic people), or a combination of both factors.
Furthermore, it has been suggested that assessments of children with suspected ASD be evaluated within a developmental framework, include multiple informants (e.g., parents and teachers) from diverse contexts (e.g., home and school), and employ a multidisciplinary team of professionals (e.g., clinical psychologists, neuropsychologists, and psychiatrists).As of 2019, psychologists wait until a child showed initial evidence of ASD tendencies, then administer various psychological assessment tools to assess for ASD. Among these measurements, the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) are considered the "gold standards" for assessing autistic children. The ADI-R is a semi-structured parent interview that probes for symptoms of autism by evaluating a childs current behavior and developmental history. The ADOS is a semistructured interactive evaluation of ASD symptoms that is used to measure social and communication abilities by eliciting several opportunities for spontaneous behaviors (e.g., eye contact) in standardized context. Various other questionnaires (e.g., The Childhood Autism Rating Scale, Autism Treatment Evaluation Checklist) and tests of cognitive functioning (e.g., The Peabody Picture Vocabulary Test) are typically included in an ASD assessment battery. The diagnostic interview for social and communication disorders (DISCO) may also be used. Screening
About half of parents of children with ASD notice their childs atypical behaviors by age 18 months, and about four-fifths notice by age 24 months. If a child does not meet any of the following milestones, it "is an absolute indication to proceed with further evaluations. Delay in referral for such testing may delay early diagnosis and treatment and affect the [childs] long-term outcome."