Older children might try to learn everything about a single topic, such as the weather or sports, and perseverate or talk about it constantly. Sensory reactivity– An unusual reaction to certain sensory inputs such as having a negative reaction to specific sounds or textures, being fascinated by lights or movements or having an apparent indifference to pain or heat.Autistic individuals can display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (RBS-R) categorizes as follows. Stereotyped behaviors: Repetitive movements, such as hand flapping, head rolling, or body rocking. Compulsive behaviors: Time-consuming behaviors intended to reduce anxiety, that an individual feels compelled to perform repeatedly or according to rigid rules, such as placing objects in a specific order, checking things, or handwashing. Sameness: Resistance to change; for example, insisting that the furniture not be moved or refusing to be interrupted. Ritualistic behavior: Unvarying pattern of daily activities, such as an unchanging menu or a dressing ritual. This is closely associated with sameness and an independent validation has suggested combining the two factors. Restricted interests: Interests or fixations that are abnormal in theme or intensity of focus, such as preoccupation with a single television program, toy, or game. Self-injury: Behaviors such as eye-poking, skin-picking, hand-biting and head-banging. Self-injury
Self-injurious behaviors (SIB) are relatively common in autistic people, and can include head-banging, self-cutting, self-biting, and hair-pulling. Some of these behaviors can result in serious injury or death.
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%).