| Autism is a broad diagnosis based on a prescribed social deficit. Diagnosis is primarily determined by behavioral evaluation, and not by genetic investigation. As such, it likely encompasses a broad range of etiologies. Without well-understood etiological causes and effects, it is not surprising that there are no reliable methods of matching an affected individual with the most appropriate intervention. The challenge of finding the best treatment for each individual stems from the probability that there are multiple causes of autism leading to multiple types which would likely respond differentially to treatments.;The goal of this project was to determine the viability of utilizing physiological profiling to distinguish subgroups of autism. In order to lay the foundation for such a task, it was necessary to identify if unique physiological profiles exist for related groups of developmental disorder. To this end, groups of adolescent boys who had comorbid diagnoses of autism and fragile X syndrome were compared with groups of children who had either idiopathic autism or fragile X syndrome without comorbid autism, as well as those who are developing typically. Physiological measures included potentiated startle response, electrodermal orienting response, electrodermal response, heart rate variability, and vagal tone. Based on the results of this study, it appears that discrete physiological profiles across all four groups of interest may indeed exist.;The work presented here is novel in that it considers autism status and fragile X status separately. The vast majority of research in both fields tends to focus on either autism status, or on fragile X status. The results of this study offer empirical evidence to support the consideration of both these statuses when investigating either. Based on the presented analyses, it appears that those individuals who are comorbid for both autism and fragile X have discrete patterns of arousal that distinguish them from either the fragile X alone or the autism groups. Consideration of comorbidity is a critical, and generally neglected component of research designed to uncover specific etiologies, or to inform behavioral and pharmacological treatments. |
