Autism

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Diagnosis

Diagnosis of autism is usually made by the age of 3. Early diagnosis and treatment often helps to improve outcome for patients. Diagnosis includes the following:

• Physical examination (may include neurological examination)
• Medical history (includes family history, birth history, and early development)
• Medical tests (to rule out other conditions)

Physicians use various screening tools to evaluate development, communication and language skills, and interaction with others. They usually question caregivers about the child's development (e.g., Did the child babble, point, wave, and grasp objects by 12 months of age?) and observe the child closely during office visits.

Differential Diagnosis

Conditions that cause symptoms similar to autism include the following:

• Asperger's syndrome
  
• Childhood disintegrative disorder
  
• Rett disorder
  
• Pervasive development disorder-not otherwise specified (PDS-NOS)
  
• Childhood psychoses (e.g., schizophrenia)
  
• Fragile X syndrome (more common in males; may cause mental retardation)
  
• Hearing loss
  
• Metabolic disorders
  

Tests performed to rule out other conditions include the following:

• Blood tests (to rule out metabolic disorders that affect amino acids and lipids in the blood)
  
• Chromosomal analysis (to rule out genetic disorders)
  
• Comprehensive hearing test (to rule out deafness as the cause of abnormal language development)
  
• Electroencephalogram (EEG; to rule out seizure disorder)
  
• Magnetic resonance imaging (MRI scan; to rule out brain disorders)
  

Asperger's syndrome is sometimes considered a variation of autism. It is more common in boys, usually develops after the age of 3, and usually does not require lifelong care. Children with Asperger's have narrow interests, repetitive routines, and are at increased risk for developing depression and anxiety. Symptoms include the following:

• Excellent rote memory (usually)
  
• Excellent musical ability (often)
  
• Inability to use language to communicate
  
• Lack of facial expressions and emotion
  
• Limited interests and an intense interest in one or two areas
  
• Severely impaired social interaction
  
• Undeveloped motor skills
  

See more on Asperger's syndrome.

Childhood disintegrative disorder causes marked deterioration of intellectual, social, and language skills around the age of 3 or 4. The disorder is associated with seizures and is more common in boys. Patients with the condition usually require lifelong care. Childhood disintegrative disorder causes loss of the following:

• Bowel and bladder control
• Language (i.e., ability to communicate and understand others)
• Motor skills
• Social skills (e.g., ability to play, develop peer relationships)

Rett disorder is a progressive neurological disorder that occurs only in girls. Symptoms of the disorder usually develop between 6 and 18 months of age. It is characterized by the following:

• Abnormal gait
• Inability to control hand movements
• Inability to express feelings
• Reduced brain size and weight (microcephaly)
• Reduced muscle tone (hypotonia)
• Seizures

Patients also may experience constipation, breathing difficulties, weakness of the extremities, and cognitive regression. There is no cure for Rett disorder, but symptoms usually can be managed with appropriate treatment.

Pervasive developmental disorder-not otherwise specified (PDD-NOS) is characterized by delayed development of social and communication skills. It usually develops between 2 and 12 years of age. Individual attention and medication to manage behavioral problems can be beneficial. Symptoms include:

• Abnormal play behavior
• Desire for sameness in their environment
• Difficulty using and understanding language
• Impaired ability to relate to people, objects, and events
• Repetitive movement and behavior
• Self-injury
• Unusual mannerisms

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