What are Autism spectrum disorders (ASD)?

Autism spectrum disorders (ASD) are neuro-developmental disorders (impairment of the growth and development of the brain or central nervous system), which arise in birth or in very early life.

The term ASD includes both autism and Asperger’s Syndrome. It is clear that a wide range (spectrum) of function is included in ASD. It is more common in boys than girls.

The defining characteristics are abnormalities of -:

• social interaction,
• communication; and
• behaviour (rigid, stereotyped, repetitive patterns of unusual behaviour and heavy reliance on routines).

Autism and Pervasive Development disorder (PDD)

Pervasive development disorder (PDD) is an umbrella term covering five disorders, all of which are characterised by delays in the development of several functions - primarily socialisation and communication. The pervasive developmental disorders are -:

• Autism

• Asperger syndrome;

• Rett syndrome; and

• Childhood disintegrative disorder (CDD)

• Pervasive developmental disorder not otherwise specified (PDD-NOS), which includes atypical autism and Pathological Demand Avoidance Syndrome

So, PDD is not necessarily autism, but the boundaries between the conditions are not fully established as it is a diagnostic grey area. Functionally, the areas of dysfunction are essentially the same as autism. Therefore, the key in examining a case that indicates only PDD is the functional classification into 'high or low functioning' (see autism guidance), which is largely dependent on whether a learning disability is present or not.

Other conditions that may accompany ASD

Learning Difficulties: Many children with ASD have some degree of mental impairment. The learning difficulty may be in a particular area, for instance, a child with ASD may do well on the parts of a cognitive test that measures visual skills but earn low scores on the language subtests.

Epilepsy: The epilepsy risk is linked to lower IQ. About one in four children with ASD develop seizures, often starting either in early childhood or adolescence.

See Epilepsy guidance.

Fragile X syndrome: This disorder is an inherited form of learning difficulty.

Tuberous Sclerosis: Tuberous sclerosis is a rare genetic disorder that causes benign tumors to grow in the brain as well as in other vital organs. It has a consistently strong association with ASD.

See ADHD guidance.

Anxiety/Depression:

Anxiety is an unpleasant emotional state characterised by fearfulness and unwanted and distressing physical symptoms.

Depression is a mental state of depressed mood characterized by feelings of sadness, despair and discouragement.

Obsessive Compulsive Disorder:

Obsessive Compulsive Disorder (OCD): A mental illness characterised by obsessive thoughts that causes anxiety. This leads to rituals or repetitive actions e.g. constantly washing hands, to relieve the anxiety.