The diagnosis of autism has increased dramaticlly in recent years.  While there is debate as to whether this increase is due to greater awareness of the autism spectrum diseases (ASDs), the benefits of early treatment and intervention for autism is clear.  It is therefore imperative for the physician caring for infants and children to be able to screen their patients for social and language developmental milestones. Parents are often the first to express concerns and the physician must listen carefully because parental reports of delays and differences in their child are often reliable.

Epidemiology
The incidence has been reported to be as high as 6,6 in 1,000 children and the recurrence rate is approximately 3-7% in subsequent children.  Advanced parental age has been shown to have some association with having children with ASD, as have some environmental exposures.  But autism is currently believed to be primarily a genetic phenomenon. 
While the possible causes and risk factors for autism are still being elucidated, it is worth noting that after thorough scientific  studies, there has been no link to childhood vaccinations or mercury exposure. 

Autistic Spectrum Disorders (ASD)

1. Autistic Disorder

a. Qualitative impairment in social interactions

b. Qualitative impairment in communication

c. Restricted repetitive and stereotyped patterns of behavior, interests, and activities

d. Abnormalities not otherwise explained by other disorders

e. Onset prior to 3 years of age

2. Asperger's Disorder- (High-functioning form of autism) Social ineptness and difficulty making friends, often normal or above normal scores on standardized tests, no speech difficulties, narrow range of interests and often clumsy

3. Pervasive Developmental Disorder not otherwise specified (PDD-NOS)- less severely disabled children who do not meet criteria for autistic disorder or Asperger's

4. Disintegrative disorder- Early development is normal and then between 2-10 years of age there is regression affecting language, sociability, intelligence, skills of daily life.

5. Rett's syndrome- Usually girls with severe global regression. Other neurological deficits. Often have characteristic hand movements.

Characteristics of Autism

1. Severe delays in language or peculiar patterns of speech

2. Social delays- poor eye contact, resists touching, appears "tuned out", poor interactions and lack of interest in peers and family members.

3. Unusual response to sensory stimuli.

4. Intellectual functioning is often uneven with being exceptional at certain skills such as drawing, music, mathematical computations, and memorization. While mental retardation is often associated with ASDs, some studies have shown global developmental delay or mental reatardation occurs in asa few as 26% of patients. 

5. Ritualistic movements and obsessive compulsive behaviors

6. Extreme hyperactivity or passivity. May demonstrate risky-dangerous behaviors.

7. Most children have a normal physical appearance and examination.

Diagnosis

1. Because there are no pathognomonic signs, physical findings. or laboratory tests to detect ASD, the physician must be suspicious after a careful evaluation.

2. If appropriate screening suggests autism, the family and child should be fully evaluated by professionals that are experts in autism.  The AAP currently recomends that all children be screened for ASDs between 18 and 24 mnonths of age.  Sveral screening tools exist to make this assessment.
     a. The Checklist for Autism in Toddlers (CHAT) is the only ASD screening tool with long-term follow-up  in both screen posituve and screen-negative patients.  Very low sensitivity in children < 18 months old.
     b. The Modified Checklist for Autism in Toddlers (M-CHAT) is a broadaer screening tool than the CHAT.  If used correctly, with follow-up interview with the parents, the sensitivity of this tool is estimated to b about 85%.
    c.  Screening Tool for Autism in Two-year -olds (STAT) is a useful tool for autism screening and has been cited in one study ashaving a sensitivity and specificity of 95% and 73% respeectively.

3. Absolute indications for immediate evaluation include:

   a. No babbling by 12 month of age

   b. No pointing or gestures by 12 month

   c. No single words by 18 months

   d. No two word phrases by 2 years of age

   e. Any deterioration of language or social skills

References

1. American Academy of Pediatrics. The Pediatrician's Role in the Diagnosis and Management of Autistic Spectrum Disorder in Children. Pediatrics Vol. 107 No. 5 May 2001

2. American Academy of Pediatrics. Technical Report: The Pediatrician's Role in the Diagnosis and Management of Autistic Disorder in Children. Pediatrics Vol. 107 No. 5 May 2001

3. Rapin Isabelle. The Autistic Spectrum Disorders. NEJM Vol. 347 No.5 August 1, 2002

4. Madsen Kreesten Meldgaard, Hvid Anders, et al. A Population-Based Study of Mesles, Mumps, and Rubeela Vaccination and Autism.  NEJM Vol 347 No. 19 Nov. 7, 2002

5. Practice Parameter.  Screening and diagnosis of autism: Report of the Quality Standard Sub-Committee of the American Academy of Neurology and the Child Neurology Society.  Neurology Vol. 55(4) August 22, 2000

6. Chouieri R. and Bridgemohan C.  To make the biggest difference, screen early for autism spectrum disorders.  Contemporary Pediatrics October 2005

7. Johnson C. Autism Pediatrics in Review March 2008

8 . American Academy of Pediatrics. Identification and evaluation of children with Autism spectrum disorders.  Pediatrics 2007; 120(5) 1183

9. Zwaigenbaum L et al.  Clinical Assessment and Mangement of Toddlers with Suspected Autism Spectrum Disorder: Insights from Studies of High-Risk Infants.  Pediatrics May 2009