Autism affects the way a person communicates and interacts with other people.
It is a neurological condition caused by differences in the structure and functioning of the brain. It is largely genetic in origin and is often inherited from parents who themselves are autistic to some degree.
It is considered a mental or learning disability, rather than a mental illness.
Individuals with autism often have trouble understanding non-verbal communication (body language), that is so important in social interaction. Often they will have trouble recognizing other people’s emotions and expressing their own. They can appear anxious or uncomfortable in social situations and will often go to great lengths to avoid them all together.
It is however, a very complex disability, and although all autistics will have a common core of symptoms, the presentation of autism is hugely variable.
Autism varies in severity from profoundly disabling, where the individual has a serious learning disability requiring constant care, to the other extreme where the person is fully independent and may have a successful career and family life. (Many famous scientists, artists and writers have been posthumously diagnosed with autism by respected experts. Some go as far as to say that autism was integral to their talents and success.
This variation in severity is why autism is described as a "spectrum" condition and hence the term Autistic Spectrum Disorder (ASD). There are many terms in use to describe the severity and other features of ASD’s, Severely autistic people are often referred to as having Low Functioning Autism (LFA), less severely affected as High or Very High Functioning Autism (HFA, VHFA). Asperger’s Syndrome is a form of High Functioning Autism where the individual has normal or above normal intelligence. Other terms include Pervasive Developmental Disorder, Not Otherwise Specified (PDD-NOS), Classic or Kanner’s Autism and Atypical Autism. Rett's Syndrome, which only affects girls, is also considered an ASD.