Autistic Spectrum Disorders

Also known as Pervasive Developmental Disorder (PDD), this category contains five specific disorders:
1. Autistic Disorder - Four times more common in males, individuals with this disorder have a moderate to severe range of communication, socialization and behavior deficits.
2. Asperger's Syndrome - A milder variant of Autistic Disorder characterized by social isolation and eccentric behavior.
3. Retts's Disorder - Occurring primarily in females, Rett's Disorder is characterized by a normal development during the first few months of life, followed by a rapid deterioration in development resulting in symptoms which can include loss of motor and language skills, slowed head growth and repetitive hand movements.
4. Childhood Disintegrative Disorder - A rare but severe disorder in which a child will develop normally for the first 3 or 4 years and then regress to a much lower level of functioning, typically following a serious illness, such as an infection of the brain and nervous system.
5. PDD-NOS (Not Otherwise Specified) - This diagnosis is assigned when symptoms do not meet a specific criteria or are not at the degree of impairment defined in any of the prior four disorders, yet there is some level of impairment in social interaction or verbal and nonverbal communication skills.

More recently, the term Multisystem Developmental Disorder (MSDD) has been defined to diagnose children under the age of 3 who exhibit signs of impaired communication, and/or impaired social skills. The main difference between MSDD and PDD is that MSDD is assumed to be a secondary impairment, linked to difficulties with sensory integration.