Pervasive Developmental Disorders (PDD), Autistic Spectrum Disorders (ASD) and autism are general terms for a wide and complex group of developmental alterations.
These alterations are characterized, at different levels, by difficulties in social interaction, in verbal and non-verbal communication and by the existence of repetitive behaviours.
So it is frequently possible to observe problems with language, cognitive processing, the expression of emotions and so on.
ASD has a neurological basis, which means that it affects brain functioning. But, depending on the way ASD affects each person and the severity of their symptoms, it is highly variable and individualized for each person.
This is why it is extremely difficult to generalize about symtomatology, and it frequently means that early diagnosis is missed because the person doing the diagnosis is not an expert in the area.
Epidemiological data on the prevalence of ASD, as reported by reputable research and websites, shows that it affects one in every 681 2 children. What seems to remain stable over time is the proportion of boys affected, between three and four times greater than the number of girls.
ASD encompasses a group of developmental alterations, each with their own denomination, such as: classic autism, Rett syndrome, childhood disintegrative syndrome, fragile X syndrome, pervasive developmental disorder not otherwise specified and Asperger syndrome.
ASD can be associated with alterations in intellectual functioning, difficulties in motor coordination, attention and some aspects of health such as sleep and gastrointestinal alterations.
It is also possible to find people within the autistic spectrum who display special abilities in the fields of visual skills, music, mathematics or art.
The onset of ASD seems to occur in the very early stages of cerebral development. However the most obvious indications and the symptoms of autism tend to emerge between the ages of 2 and 3.