Autism Spectrum Disorders (ASDs) are complex lifelong neurodevelopmental and behavioral disorders manifesting in infancy or early childhood, characterized by impairments in social interaction and communication, and by repetitive, stereotyped behavior. The prevalence of ASD appears to be on the rise in developed countries, and has become a serious public health concern. In most developing countries, however, the nature and prevalence of factors associated with ASDs are unknown.
Objectives:
In collaboration with researchers at the University of West Indies (UWI) in Kingston, Jamaica, we are conducting this study to compare ASD case-finding and case-ascertainment approaches. Additionally, we are investigating whether environmental exposures to mercury, lead, arsenic and cadmium play a role in autism. Furthermore, we are assessing the role of select polymorphisms in glutathione-S-transferase (GST) genes, and their potential interactions with the aforementioned heavy metals in relation to ASD.
Methods:
This is an age and sex matched case-control study. We are administering the Autism Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic Interview-Revised (ADI-R) to 225 children in the UWI’s Jamaica Autism Database who have previously been identified as being at risk for ASD using the Childhood Autism Rating Scale (CARS). Our goal is to identify 150 children with an ADOS-ADI-R confirmed ASD. For each case, we will also identify an age and sex matched control using the Social Communication Questionnaire (SCQ). We also administer a pre-tested questionnaire to assess demographic and socioeconomic information, parental history, and potential exposure to heavy metals through food or occupation of parents. At the end of the interview, we collect 5 mls of whole blood, 2 mls of saliva, and hair samples to be analyzed in the US. Using conditional logistic regression, we assess the role of GST genes, and their potential interactions with heavy metals in relation to ASD.
Results:
A preliminary analysis of the ongoing Jamaica Autism Database identifies 411 children with ASD during 1996 - present. About 83% of cases are male resulting in a sex ratio of 4.9:1 (Male:Female ratio). Approximately half of the ASD cases are younger than or equal to 8 years, making them eligible to participate in our study. Our Jamaican team members received ADOS and ADI-R training in the US. Our Genetics team visited UWI in October 2009 to provide training for the collection, processing and shipment of biological specimens.
Conclusions:
This study will lay out the foundation for the first epidemiological study of ASD in an Afro-Caribbean population. Although we have not yet completed our data collection, we have gained significant insight in conducting epidemiological research on autism in other cultures. For example, despite our target population being from an English speaking part of Jamaica, we have experienced some subtle cultural differences between Jamaica and the US that may require attention with respect to the administration of particular components of the ADOS. In addition, we have gained significant insight in potential logistical challenges with respect to transportation of specimens from other countries into the US. We believe our experience will be useful to other researchers.