OverviewThe DSM-IVTR criteria for Autism SpectrumDisorders (ASDs) require delays or abnormalfunctioning in social interactions, language as usedin social communication, and symbolic orimaginative play, with onset prior to age 3. Inaddition to abnormal social behavior, ASDs arefrequently, but not always, associated with reducedIQ and epilepsy. Individuals who exhibit someautism-like symptoms with relatively preservedcognitive functioning and language skills aredescribed as having Aspergers syndrome.
EpidemiologyThere has been a dramatic increase in the diagnosis of ASDs,from 1/1000 (1950s–1990s) to a current level of 1/150.Whether this increase reflects increased disease prevalenceremains uncertain; ongoing studies are searching for genetic,environmental, and sociologic mechanisms that may havecontributed to this change. In the 1950s–1960s, psychologicalfactors were held to underlie autism. This conception waslargely debunked by the 1970s, with the demonstration thatprenatal rubella and phenylketonuria can cause ASDs, andwith evidence for the genetic etiology of ASDs from twinstudies.
Neuropathology and NeuroimagingThere is a modest increase in cerebrum growth(10%; affecting both the white and grey matter)during early childhood (years 1–3), with the largesteffect in the frontal lobes; the growth rate thendecreases with age. Cerebellar size is increased byabout 7% in children under age 5 years, but isdecreased in older patients, and there are reduced(30%) numbers of cerebellar Purkinje neurons.Finally, there is reduced cell size and increased celldensity in the limbic areas of the brain.
PathogenesisThese include mutations in proteins involved in the formationand function of synapses, control over the size andprojections of neurons, production and signaling ofneurotransmitters and neuromodulators, the function of ionchannels, general cell metabolism, gene expression, andprotein synthesis. Many of these mutations have a clearrelationship to activity-dependent neural responses and canaffect the development of neural systems that underliecognition and social behaviors. They may be detrimental byaltering the balance of excitatory vs. inhibitory synapticsignaling in local and extended circuits, and by altering themechanisms that control brain growth.
A U T I S M A.L .A.R .M .Autism is prevalent• 1 out of 6 children are identified with adevelopmental disorder and/or behavioralproblem• Approximately 1 in 88 children arediagnosed with an autism spectrum disorder• Developmental disorders have subtle signsand may be easily missed
Listen to parents• Early signs of autism are often presentbefore 18 months• Parents usually DO have concerns thatsomething is wrong• Parents generally DO give accurate andquality information• When parents do not spontaneously raiseconcerns, ask if they have any
Act early• Make screening and surveillance an important partof your practice (as endorsed by the AAP)• Know the subtle differences between typical andatypical development• Learn to recognize red flags• Use validated screening tools and identifyproblems early• Improve the quality of life for children and theirfamilies through early and appropriate intervention
Refer• To Early Intervention or a local schoolprogram (do not wait for a diagnosis)• To an autism specialist, or team ofspecialists, immediately for a definitivediagnosis• To audiology and rule out a hearingimpairment• To local community resources for help andfamily support
Monitor• Schedule a follow-up appointment to discuss concerns morethoroughly• Look for other conditions known to be associated withautism (eg, seizures, GI, sleep, behavior)• Educate parents and provide them with up-to-dateinformation• Advocate for families with local early interventionprograms, schools, respite care agencies, and insurancecompanies• Continue surveillance and watch for additional or late signsof autism and/or other developmental disorders• Continue to provide a medical home