Autism is a pervasive disorder of brain development that severely affects socialization, communication and can even cause obsessive or repetitive behaviors. Autism delays normal brain development and is also correlated with a milder form of the syndrome known as pervasive developmental disorder not otherwise specified (PDD-N OS). Since its first identification in 1943, the number of new diagnoses has increased each year. Muhle, Trenracoste, and Rapin (2004) found that the autism diagnosis rate increased by 556% between 1991 and 1997. Many believe this increase is due to a change in diagnostic criteria or new defining characteristics of the syndrome . . The expansion of diagnostic criteria is also indirectly linked to the increase in services provided to children with autism, thereby increasing change. Due to this increase in the number of diagnoses, there was increased awareness among pediatricians, which further increased the rate of autism diagnoses (“Autism,” 2010). Glasson et al. (2004) found that the frequency with which this disorder is diagnosed has increased to almost 60 per 10,000 people. Another factor behind the increase in autism diagnosis is that children are being diagnosed at a much earlier age. Parents identify problem behaviors earlier in a child's life, sometimes as early as 8 months of age (Bristol-Power & Spinella 1999). Studies have shown that autism is more common in boys than girls, with a male/female ratio of 3:1 (Muhle et al., 2004). It's not clear why autism tends to develop in men rather than women, but the fact that men are statistically more likely to develop autism suggests that genes associated with the X sex chromosome may... .... middle of paper .... ....sometimes significantly improves the child's behavioral skills. Works Cited Autism. (nd). Retrieved from: http://www.nlm.nih.gov/medlineplus/ency/article/001526.htmBaron-Cohen, S., Ring, HA, Bullmore, ET, Wheelwright, S., Ashwin, C., Williams, RCS (2000). The amygdala theory of autism. Neuroscience and Biobehavioral Reviews 24, 355-64 Bristol-Power, M. & Spinella, G (1999). Research on autism screening and diagnosis: a work in progress [Abstract]. Journal of Autism & Developmental Disorders 29, 435Glasson, E., Bower, C., Petterson, B., Klerk, N., Chaney, G., Hallmayer, F. (2004). Perinatal factors and the development of autism: a population study. Arch Gen Psychiatry 61,618-27Muhle, R., Tentacoste, SV., Rapin, I. (2004). The genetics of autism [Abstract]. Pediatrics 5, 472-86National Institute of Child Health and Human Development (2005).