Ah yes, the $64,000 question. Well, the dictionary definition
is
Autism (psychiatry)n absorption in imaginative activity directed
by thinker's wishes, with loss of contact with reality; an abnormality of
childhood development affecting language and social communication
Chambers Dictionary
In modern terms, there are a whole range of conditions associated with autism, and this has given rise to the relatively modern concept of the Autistic Spectrum, ranging from "milder" forms of autism such as attention deficit disorder or Aspergers Syndrome, to the more serious classical forms of the condition.
All those who suffer from autism or related conditions show 3 main areas of
difficulties, which is known as the Triad of Impairments:
The jury is stillout on this one (quite literally - see below). It is generally agreed that it is related to problems with brain development. This can be caused before, during or after birth. It is also generally agreed that classical autism has a genetic basis. However, newer conditions are being diagnosed as regressive or aquired autism. The main difference is that children with this new form have developed normally (or are above average) before the regression kicks in. Unlike classical autism, regressive autism can kick in at a later stage in development (i.e. well after 18 months to 2 years of age). Arguments rage as to whether some types of autism are linked to the Mumps Measles and Rubella (MMR) vaccine at the age of 15 months, or are linked to forms of bowel disorder. This site does not deal with those arguments, though you may wish to read further (see the links at the bottom of this page).
Rory is being helped with the ABA method.
for more reading on the subject, try these links: