Early Detection of Autism in Infants and Toddlers (Part 2)
Problems Associated with the Reliability of Parental Report of Early Symptoms
Due to the fact that parents spend the most time with their young children, both mother and father are considered to be in the best position logically to provide historical background information pertaining to developmental delays, skill regression, patterns of behavior, and behavioral difficulties shown by their children with suspected autism. Despite this remark, Goin & Myers determined that parent and family caregivers, as the most intimate observers of their own children, can deviate from objectivity in their recall of behaviors (2004). Moreover, due to the fact that twenty to forty percent of parents report a normal developmental course for their child up until an observed regression point, the examination of extremely early symptoms of infants later diagnosed with autism becomes limited to a smaller percent who have experienced consistently slow developmental milestones (Volkmar et al. 2005). Less frequently, evidence of autistic symptoms may be apparent in children under the age of three, and thus, compiled in data to determine the earliest diagnostic criteria, but these behaviors may become less obvious as the child matures. Finally, due to the fact that seventy-five percent of children with autism are mentally retarded, it is possible that the symptoms parents report in infants with autism are more so related to mental retardation and not at all autism specifically (Osterling et al. 2002). These weaknesses in terms of the reliability of parental report necessitate further investigation before an exact definition of autism can be developed in very early infants.
Overview of Early Symptomology as Assessed by Experienced Clinicians
Parents are often asked to participate in the systematic study of their children’s autistic behaviors by experienced researchers, even when direct observational reports are not requested in the form of parental interview as were described previously. With the technological revolution in the past decades in the United States, video cameras have become increasing accessible to families across the nation, and therefore, many parents inadvertently provide detailed documentation of their child’s development which can be utilized in research. According to Baranek in 1999, “retrospective video analysis has shown success as an ecologically valid methodological tool for earlier identification of children with various psychopathologies,” (220), and consequently can provide significant reliability and validity to parental report of behaviors.
Such is the case in an experiment conducted by Volkmar et al. (2005) where age-matched infants with autism were compared to typically developing infants, and differences in visual attention to social stimuli, smile frequency, vocalization, and object exploration engagement were examined. At twenty months of age, behaviors in facial expression, use of conventional gesture, and pointing to indicate interest were distinguishing criteria. In a follow-up retrospective video analysis between twelve and fifteen months later, groups were identified by social activities such as seeking shared enjoyment, social reciprocity, use of another person as a tool, interest in other children, and in communicative tasks, (e. g. attending to voice, pointing, using and understanding gesture). A similar study determined that by the age of three, finger mannerisms, attention to voice, pointing, and the use of other person’s body were able to correctly classify all subjects recruited in the experiment as either autistic or typically developing by examining videotaped interactions of young infants (Cox, Charman, Baron-Cohen, Drew, Klein, Baird, Swettenham, & Wheelwright, 1999). When first birthday party video tapes were viewed by Osterling & Dawson, a significant main effect of the diagnostic group was found for the category of social behavior, including looking at the face of another, seeking contact, imitating, and for the category of joint attention behaviors, pointing vague pointing, showing, as well, but not for the category of communicative behaviors of following directions and babbling (1994). In these videos, it was determined that the autistic subjects showed significantly more abnormal systems such as ear covering and self-stimulation, and as a result, ninety-one percent of all cases were correctly identified, providing solid evidence that professionals should thoroughly evaluate infantile use of eye contact, joint attention behaviors, and orientating to speech when determining appropriate diagnostic measures. Baranek found similar results when comparing infants with mentally retarded participants, in that those with autism exhibited poor visual attention, required more prompts to respond to their name, excessively mouthed objects, and more frequently showed aversion to social touch (1999). Furthermore, in a study aimed to characterize infants with autism spectrum disorders under the age of one, five behavior abnormalities were documented through retrospective video analysis which included poor social attention, lack of social smiling and appropriate facial expressions, hypotonia, and unstable attention (Werner, Dawson, Osterling, & Dinno, (2000).
Neurological Abnormalities as Diagnostic Criteria
To evaluate the significance of the previously reported behavioral characteristics found in various research studies, one must examine the neurological abnormalities occurring in the brains of those with autism. In determining the rationale for each observed behavior, it is important to establish that many core deficit behaviors can be linked to underlying neurological problems, whereas “secondary manifestations may be a product of an individual’s approach to coping with the disorder or other disorders that may coexist,” (Young et al. 2003), such as an intellectual disability. The cerebellum, medial temporal structures, and prefrontal cortex have been recognized as possible core regions of abnormality in autism spectrum disorders (Dawson, Meltzoff, Osterling, & Rinaldi, 1998), and perhaps the imaging process of an fMRI, MRI, or CT scan of the brain during infancy could diagnose children very early before symptoms appear, as brain differences would most likely precede observed behaviors. Further evidence supporting the notion that the medial temporal lobe of an individual’s brain is a primary player in the manifestation of autistic symptoms is found when lesions are made in the hippocampus and amygdala early in the development of monkeys.