Autism is a complex spectrum of cognitive disorders, affecting language, communication and socialization. Autistics often do not understand and thereby miss pertinent social cues, body language and facial expressions. Emotional intelligence tends to be compromised, which can appear as lack of empathy with others, making social situations awkward and/or difficult. Autism is considered to be a subset disorder under the heading of Pervasive Developmental Disorders which along with Autism includes Rhett's Syndrome, Fragile X and Childhood Disintegrative Disorder.
Autism as a specific disorder is part of the Autism spectrum of disorders which currently includes Asperger's syndrome. There is no clear point where someone is clearly autistic, and there is no clinical diagnostic test for Autism. Each case is diagnosed by qualitative observation by a team of caregivers and professionals.
Since 1944, when Austrian psychologist Hans Asperger published his first paper about what he called "autistic psychopathy", the psychiatric community has become increasingly aware that high-functioning people with autism-like symptoms are not "psychopaths", as they were once labeled. We also now know that autism is a spectrum of traits and disorders with varying levels of severity. Depending on the amount of woo involved, the fact that people who present unusual but not dysfunctional behavior can be diagnosed with autism (and suffer the consequences) can be used as rational criticism of modern clinical psychology, or as fodder for crank theories about autism being a higher level of evolution.
 Causes and controversy
There has been a marked increase in the number of diagnosed cases of autism in recent years, but the true incidence and possible cause has been hotly debated. Some think the rise in reported cases may be simply due to more awareness of the syndrome, coupled perhaps with defining it more broadly to include the whole autistic spectrum. There is some evidence that more severe cases of autism may be genetic in nature while less severe cases are merely the result of an individual's aptitudes being skewed.
It has been recently shown that the deletion of a section of chromosome 17 results in a 14-fold increase in the chance of having schizophrenia or autism spectrum disorders. David H. Ledbetter, a genetics professor at Emory University stated "Not all people with autism, a developmental delay or schizophrenia have this deletion, but all people who have the chromosome change will develop some form of the disorders, whether it's mild or strong enough for a diagnosis".
Recent research has revealed a so-called "insanity virus," called human endogenous retrovirus W or HERV-W, which so far has been shown to be connected to Schizophrenia, Bipolar Disorder and Multiple Sclerosis. Researchers are proposing a similar tie-in with a version of Herpes Simplex Virus attached to DNA as a possible cause of Autism.
Genetic interactions are quite complex, but this has shed light on a major piece of the puzzle.
 Vaccine hysteria
In the 1990s and the 2000s, vaccine hysteria linking childhood vaccinations to autism broke on both sides of the Atlantic. In the UK, it was fueled by Andrew Wakefield's study implicating the MMR vaccine. In the US, the focus was on thimerosal, a preservative used in some "dead" vaccines. Both hypotheses have been thoroughly discredited by the medical community worldwide, yet some people still hold on to this idea.
 Pseudoscientific treatment
Because Autism is so poorly understood and caregivers often feel helpless in the face of it, many pseudoscience and alternative medicine promoters have been attracted to autism, offering up such "cures" as chelation therapy and lupron therapy. As with most alternative therapy, the results and effectiveness are not scientifically verified. Some therapies such as chelation and specialized diets can in fact be harmful.
Autism is occasionally coupled with a type of precociousness that is called "savant". A so-called autistic savant has difficulty with personal communication and utilizing broader knowledge, but excels beyond all comprehension at a single subject, usually in the fields of memory, music, or mathematics. Although this is a rare occurrence, the impressive abilities of the individuals are often widely reported. Why they excel in a specific field is unknown, though some have speculated that they may find some comfort by focusing their attention and energies on that field.
 See also
- Opposing Views: Are Autism and Vaccines Linked?
- Is There an Autism Epidemic? - Dr Steven Novella discusses the confounding variables when trying to claim that autism rates are on the rise.