The number of people diagnosed has increased considerably since the 1990s, which may be partly due to increased recognition of the condition.While rates of ASD are consistent across cultures, they vary greatly by gender, with boys diagnosed far more frequently than girls: 1 in 70 boys, but only 1 in 315 girls at eight years of age. Girls, however, are more likely to have associated cognitive impairment, suggesting that less severe forms of ASD are likely being missed in girls and women. Prevalence differences may be a result of gender differences in expression of clinical symptoms, with women and girls with autism showing less atypical behaviors and, therefore, less likely to receive an ASD diagnosis.Using DSM-5 criteria, 92% of the children diagnosed per DSM-IV with one of the disorders which is now considered part of ASD will still meet the diagnostic criteria of ASD. However, if both ASD and the social (pragmatic) communication disorder categories of DSM-5 are combined, the prevalence of autism is mostly unchanged from the prevalence per the DSM-IV criteria. The best estimate for prevalence of ASD is 0.7% or 1 child in 143 children. Relatively mild forms of autism, such as Aspergers as well as other developmental disorders, are included in the DSM-5 diagnostic criteria. ASD rates were constant between 2014 and 2016 but twice the rate compared to the time period between 2011 and 2014 (1.25 vs 2.47%).
First off, there are no standardized imaging, molecular or genetic tests that can be used to diagnose ASD. Additionally, there is a lot of variety in how ASD affects individuals. The behavioral manifestations of ASD depend on ones developmental stage, age of presentation, current support, and individual variability. Lastly, there are multiple conditions that may present similarly to Autism Spectrum Disorder, including intellectual disability, hearing impairment, a specific language impairment such as Landau–Kleffner syndrome. ADHD, anxiety disorder, and psychotic disorders. Furthermore, the presence of autism can make it harder to diagnose coexisting psychiatric disorders such as depression.Ideally the diagnosis of ASD should be given by a team of clinicians (e.g. pediatricians, child psychiatrists, child neurologists) based on information provided from the affected individual, caregivers, other medical professionals and from direct observation. Evaluation of a child or adult for Autism Spectrum Disorder typically starts with a pediatrician or primary care physician taking a developmental history and performing a physical exam. If warranted, the physician may refer the individual to an ASD specialist who will observe and assess cognitive, communication, family, and other factors using standardized tools, and taking into account any associated medical conditions. A pediatric neuropsychologist is often asked to assess behavior and cognitive skills, both to aid diagnosis and to help recommend educational interventions. Further workup may be performed after someone is diagnosed with ASD. This may include a clinical genetics evaluation particularly when other symptoms already suggest a genetic cause.