A 2016 paper examines Asperger syndrome as "an alternative pro-social adaptive strategy" which may have developed as a result of the emergence of "collaborative morality" in the context of small-scale hunter-gathering, i.e. where "a positive social reputation for making a contribution to group wellbeing and survival" becomes more important than complex social understanding.Conversely, some multidisciplinary research suggests that recent human evolution may be a driving force in the rise of a number of medical conditions in recent human populations, including autism. Studies in evolutionary medicine indicate that as biological evolution becomes outpaced by cultural evolution, disorders linked to bodily dysfunction increase in prevalence due to a lack of contact with pathogens and negative environmental conditions that once widely affected ancestral populations. Because natural selection primarily favors reproduction over health and longevity, the lack of this impetus to adapt to certain harmful circumstances creates a tendency for genes in descendant populations to over-express themselves, which may cause a wide array of maladies, ranging from mental illnesses to autoimmune disorders. Pathophysiology
Autisms symptoms result from maturation-related changes in various systems of the brain. How autism occurs is not well understood. Its mechanism can be divided into two areas: the pathophysiology of brain structures and processes associated with autism, and the neuropsychological linkages between brain structures and behaviors. The behaviors appear to have multiple pathophysiologies.There is evidence that gut–brain axis abnormalities may be involved. A 2015 review proposed that immune, gastrointestinal inflammation, malfunction of the autonomic nervous system, gut flora alterations, and food metabolites may cause brain neuroinflammation and dysfunction.
Although ABA therapy has a strong evidence base, particularly in regard to early intensive home-based therapy, ABAs effectiveness may be limited by diagnostic severity and IQ of the person affected by ASD. The Journal of Clinical Child and Adolescent Psychology has deemed two early childhood interventions as "well-established": individual comprehensive ABA, and focused teacher-implemented ABA combined with DSP.Another evidence-based intervention that has demonstrated efficacy is a parent training model, which teaches parents how to implement various ABA and DSP techniques themselves. Various DSP programs have been developed to explicitly deliver intervention systems through at-home parent implementation. In October 2015, the American Academy of Pediatrics (AAP) proposed new evidence-based recommendations for early interventions in ASD for children under 3. These recommendations emphasize early involvement with both developmental and behavioral methods, support by and for parents and caregivers, and a focus on both the core and associated symptoms of ASD. However, a Cochrane review found no evidence that early intensive behavioral intervention (EIBI) is effective in reducing behavioral problems associated with autism in most autistic children but did help improve IQ and language skills. The Cochrane review did acknowledge that this may be due to the low quality of studies currently available on EIBI and therefore providers should recommend EIBI based on their clinical judgement and the familys preferences. No adverse effects of EIBI treatment were found. Studies on pet therapy have shown positive effects.Generally speaking, treatment of ASD focuses on behavioral and educational interventions to target its two core symptoms: social communication deficits and restricted, repetitive behaviors.