No response to name (or gazing with direct eye contact) by 6 months. No babbling by 12 months. No gesturing (pointing, waving, etc.) by 12 months. No single words by 16 months. No two-word (spontaneous, not just echolalic) phrases by 24 months. Loss of any language or social skills, at any age.The Japanese practice is to screen all children for ASD at 18 and 24 months, using autism-specific formal screening tests. In contrast, in the UK, children whose families or doctors recognize possible signs of autism are screened. It is not known which approach is more effective. The UK National Screening Committee does not recommend universal ASD screening in young children. Their main concerns includes higher chances of misdiagnosis at younger ages and lack of evidence of effectiveness of early interventions There is no consensus between professional and expert bodies in the US on screening for autism in children younger than 3 years.Screening tools include the Modified Checklist for Autism in Toddlers (M-CHAT), the Early Screening of Autistic Traits Questionnaire, and the First Year Inventory; initial data on M-CHAT and its predecessor, the Checklist for Autism in Toddlers (CHAT), on children aged 18–30 months suggests that it is best used in a clinical setting and that it has low sensitivity (many false-negatives) but good specificity (few false-positives). It may be more accurate to precede these tests with a broadband screener that does not distinguish ASD from other developmental disorders.
Screening tools designed for one cultures norms for behaviors like eye contact may be inappropriate for a different culture. Although genetic screening for autism is generally still impractical, it can be considered in some cases, such as children with neurological symptoms and dysmorphic features. Misdiagnosis
There is a significant level of misdiagnosis of autism in neurodevelopmentally typical children; 18–37% of children diagnosed with ASD eventually lose their diagnosis. This high rate of lost diagnosis cannot be accounted for by successful ASD treatment alone. The most common reason parents reported as the cause of lost ASD diagnosis was new information about the child (73.5%), such as a replacement diagnosis. Other reasons included a diagnosis given so the child could receive ASD treatment (24.2%), ASD treatment success or maturation (21%), and parents disagreeing with the initial diagnosis (1.9%).Many of the children who were later found not to meet ASD diagnosis criteria then received diagnosis for another developmental disorder. Most common was ADHD, but other diagnoses included sensory disorders, anxiety, personality disorder, or learning disability. Neurodevelopment and psychiatric disorders that are commonly misdiagnosed as ASD include specific language impairment, social communication disorder, anxiety disorder, reactive attachment disorder, cognitive impairment, visual impairment, hearing loss and normal behavioral variation. Some behavioral variations that resemble autistic traits are repetitive behaviors, sensitivity to change in daily routines, focused interests, and toe-walking. These are considered normal behavioral variations when they do not cause impaired function. Boys are more likely to exhibit repetitive behaviors especially when excited, tired, bored, or stressed.