Minneapolis Somali autism spectrum disorder prevalence project: Community report 2013 (PDF – 2 MB) - Hewitt A, Gulaid A, Hamre K, Esler A, Punyko J, Reichle J, Reiff M. University of Minnesota, Institute on Community Integration, Research and Training Center on Community Living. 2013 Dec.
The Minneapolis Somali Autism Spectrum Disorder Prevalence Project was developed to determine if more Somali children aged 7 to 9 had ASD than non-Somali children in Minneapolis in 2010.1 The project was launched in response to community concerns that prompted an earlier analysis conducted by the Minnesota Department of Health that showed that a greater proportion of Somali children with ASD were participating in preschool special education programs in area public schools, compared with children of other races/ethnic backgrounds.2 The concerns raised by the community were shared by the Interagency Autism Coordinating Committee (IACC) and they responded by fostering a collaboration between government and private funders to support a population-based surveillance project in Minneapolis.3, 4 The main aim of the surveillance project was to determine if there was a higher prevalence of ASD among Somali children in Minneapolis than among non-Somali children, regardless of special education placement. Researchers used the same methodology employed by the Centers for Disease Control and Prevention (CDC) Autism and Developmental Disabilities Monitoring (ADDM) Network to estimate population prevalence. School and medical service records were reviewed by clinicians to identify children with ASD, based on information contained in the records that conformed to the definition of ASD outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM, Fourth Revision). Results showed that approximately 1 in 32 Somali children ages 7 to 9 were identified as having ASD in Minneapolis in 2010. Somali and White children (1 in 36) were about equally likely to be identified as having ASD and more likely to be diagnosed than non-Somali Black (1 in 62) and Hispanic (1 in 80) children in Minneapolis. An unexpected and important finding of this study was that, compared to other racial and ethnic groups, Somali children with ASD were more likely to also have an intellectual disability (IQ of less than 70) than other groups. Approximately one third of all the children with ASD identified in this study (including all ethnic groups) had an associated intellectual disability. However, 100% of the 20 Somali children with IQ included in their records had an intellectual disability, while the proportion was closer to 20% for White, non-Somali Black and Hispanic children. This finding was limited by the small number of children with ASD in the study, but suggested that Somali children may, as a group, have more severe forms of ASD than other groups. Further studies will be needed to understand this difference and the possible contribution of genetic or environmental risk factors. The study also found that children in Minneapolis are, in general, not being diagnosed as early as they could be; irrespective of racial and cultural background, the average age of receiving an ASD diagnosis is 5 years. Since ASD can now be reliably diagnosed by age 2, this finding highlights an opportunity for improvement in service provision in Minneapolis, suggesting that more efforts are needed to increase awareness, outreach, and access to diagnostic services, especially in underserved and culturally diverse areas, using culturally-sensitive approaches. As the largest study of Somali children with autism to date in the U.S., this study provides a solid foundation for future research to explore why and how autism affects Somali and non-Somali children differently and can also be used by a number of different groups (e.g., parents, providers, community groups, and advocates) to increase awareness and early intervention for children, especially in diverse communities.
Evaluating changes in the prevalence of the autism spectrum disorders (ASDs) (PDF – 838 KB) - Rice CE, Rosanoff M, Dawson G, Durkin MS, PhD, Croen LA, PhD, Singer A, Yeargin-Allsopp M. Public Health Reviews. 2013 March;34(6);2.
This article describes the outcomes of a 2011 workshop that was convened by the CDC and Autism Speaks to explore data and trends related to the rising prevalence of ASD in the U.S. and worldwide. Prevalence refers to the number or proportion of people with a particular condition, such as ASD, in a population at a given time. The identified prevalence of ASD has increased significantly in a short time period based on data from multiple studies including the U.S. Centers for Disease Control and Prevention's (CDC) Autism and Developmental Disabilities Monitoring (ADDM) Network. At the time when this article was written, the CDC's ADDM Network estimated the prevalence of ASD in the United States to be 1 in 88 children, which is greater than 1% of the population and far greater than the prevailing estimate of 1 in 2,000 that persisted through the 1980s. It should be noted that early estimates only considered autistic disorder, whereas more recent estimates used a broader definition of autism, including related "autism spectrum" diagnoses such as Pervasive Developmental Disorder–Not Otherwise Specified (PDD-NOS) and Asperger's disorder.
Workshop participants discussed the strong interest of the ASD community in understanding the reasons underlying the increased prevalence of ASD. They hypothesized that greater awareness of ASD and better identification—especially in populations with good access to healthcare—are likely responsible for some portion of the increase in ASD prevalence. Changes in genetic and environmental risk factors were also considered as a potential reason that could also account for some of the increase, but participants noted that in order to be identified as such, risk factors must be shown to be strongly associated with ASD, modifiable, and to have an effect size in the population that aligns with the increase in prevalence. The issue of health disparities was also discussed. The authors noted that ASD is more prevalent in higher socioeconomic status (SES) families, unlike many other disorders that tend to be more prevalent in lower SES families. They hypothesized that this may be related to differences in access to services, and that as services gaps are closed in underserved communities, diagnosis in the low SES population may rise. This prediction appears to have been borne out in more recent prevalence studies, with ASD prevalence rising in minority populations as outreach and services have improved; in spite of improvements, however, major disparities remain. The authors discussed the pros and cons of various prevalence measurement methodologies, including records-based estimates and screening-based estimates. They also described lessons learned from diseases where the range of symptoms and presentations (heterogeneity), and changes in risk factors or in diagnostic approaches have presented challenges for accurate determination of prevalence, including schizophrenia, Parkinson's disease, asthma, and cancer. Overall, the workshop participants summarized that changes in ASD prevalence are likely caused by a very complex combination of identification and risk factors. In order to best study these factors, collaboration both within the ASD field and with other, similar fields of study will be needed, along with maintenance and expansion of careful population data collection, and informed data analysis. Though many questions surrounding the increased prevalence of ASD remain, workshop participants concluded that even the documentation of this increase has been an important step forward, as it focuses attention on the needs of those with ASD, contributes to the development and availability of services and supports, and highlights the need for continued research.