What is Autism

Autism and Pervasive Developmental Disorders

Pervasive Developmental Disorders (PDD) are part of the childhood disorders described in the DSM IV, the Diagnostic and Statistical Manual of Mental Disorders. PDDs include five disorders:

  • Autism;
  • The Childhood Disintegrative Disorder;
  • Asperger’s Syndrome;
  • PDD Not Otherwise Specified and Atypical Autism;
  • Rett Syndrome.

Sub-groups are found in the Pervasive Developmental Disorders and Typical and Atypical Autism depending on the symptoms and the onset of the disorder. Asperger’s Syndrome characterises children with no intellectual disability and no late onset of language.

Even if efforts have been made to define the sub-groups criteria, there are always other groups in between and a child’s improvement can change the clinical assessment and thus the category in which he falls. We should therefore talk about a continuum between the different autistic disorders and focus should be put on the children’s individualised assessment of abilities and deficits. If categories are helpful to bring on a consensus on a few parameters, their usefulness in predicting evolution and which specific therapeutic strategies should apply remains uncertain.


PDD are neuro biochemical in nature and are associated with a genetic disorder. Its onset is in the first years of life. The messages sent to the brain by the senses are ill-received or ill-interpreted which results in a skewed perception of the person’s surroundings.

These problems vary in intensity and may take on different forms. Many people living with PDD may present with an intellectual disability and/or epilepsy. PDD prevalence is 22 people per 10,000 and is seen four times more often in boys than girls. People living with PDD are found in every social class and in every country of the world. Many people living with PDD may also have Down Syndrome, deafness, blindness or other disorders.

To be diagnosed with PDD, you need to present

  • Serious communication disorders: language and decoding deficits, echolalia, being non-verbal, etc.
  • Socialisation problems: the autistic person wants to communicate but cannot because of his handicap;
  • Sensory dysfunction: Dysfunction of the five senses brings about peculiar and stereotypical survival behaviours. The abnormal behaviour is directly linked to the neurological and chemical dysfunctions.

These problems vary in intensity or may present differently from one person to the next.


Autism and PDD stem from medical problems in small children. Autism and PDD are not mental illnesses and are in no way linked to psychological problems. Current research on the disorder focus mainly on immunological or gastrointestinal dysfunction resulting in food intolerances in predisposed people. Researchers are also looking at virus or fungus-caused infections that would result in metabolic imbalances which would themselves have a complex interaction with the autism.

The prevalence of autism

  • 1 child in 68 will receive a diagnosis of autism, which represents an increase of 123% since 2002. (Center for Disease Control, 2014)
  • In the province of Quebec alone, the number of students with autism has increased by 367% from 2003 to 2013 (MELS).
  • There are over 28 800 individuals with autism in Montreal and over 119 900 in the province of Quebec.



Clinical examination protocols must be created and used to determine which course of treatment each child should receive. These tests will also improve our knowledge of autism’s nature and causes. Intensive and systematic early intervention programs should also be used to improve the autistic children’s prognosis.

Our sponsors