Diagnosis of autism spectrum disorder
It has been difficult to diagnose ASD until the affected child is 3 years of age, as the clinical signs are not easily identifiable and language development is delayed [2]. Some families report social deficits (such as facial expressions, non-verbal gestures and reduced interaction) within the first few months after birth [10]. A retrospective video study published by Baranek in 1999 [11] observed the symptoms of ASD in children at 9 to 12 months and has suggested a number of early intervention procedures that involve assessment of sensory processing and sensory motor functions in addition to recording social responsiveness during infancy to diagnose ASD. Studies investigating infants at risk (siblings of affected children) have reported that deficits in communication and social interactions can be identified as early as 6 months of age [12,13]. These observations indicate that relevant neurochemical events that alter neuroanatomical growth occur early in the development of the CNS (central nervous system) [14]. Therefore, it is suggested that if we can understand the combination of events that cause the development of ASD, then we can identify women and children at risk and conceivably develop treatments to reduce symptoms associated with this condition.