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Prevalence FAQ

  1. Why are these numbers going up? Why is there such high variability across ADDM sites?
    • Improved detection of cases, as a result of better access to services and greater awareness of autism, may be contributing to the increase in prevalence.
    • Exposure to environmental factors that increase risk for autism cannot be ruled out as contributors to the increase in prevalence, but this study was not able investigate or draw conclusions about this.
    • Access to more and higher quality records as well as access to both health and service records at certain sites may account for some of the variability between sites. However, we continue to see an increase in prevalence over time across all ADDM sites.
  2. Are you surprised? What about the study conducted in South Korea? Does that shed light on the increasing prevalence?
    • The figure itself is quite shocking when you think about it. 1 in 59 children has autism in the US. What was once thought to be a rare condition is clearly no longer that. Autism should be described as nothing less than an epidemic – an urgent public health crisis requiring increased attention and a rapid response.
    • Although autism detection in the US may be improving, it is highly likely that we are still missing children and underestimating prevalence using the current methods.
    • 2.64%, or 1 in 38 children, in South Korea were found to have autism using a direct assessment approach and two-thirds of these children would have been missed using a records-only approach similar to the current ADDM surveillance in the US.
  3. Does this just reflect more diagnoses or more prevalence? Are we any closer to identifying causes?
    • This study alone cannot answer whether the increase in prevalence is a result of better detection or of increased risk for autism, but it is likely a combination of both.
    • Environmental factors and their interaction with genetic underpinnings can increase ones risk for autism, and there is a clear need to better understand the role of environment and gene-environment interactions in the increase in autism prevalence over time.
      • Based on previous research, it has been said that approximately 50% of the increase in autism prevalence can be explained by changes in diagnostic approaches (broader diagnosis), greater awareness, and increased parental age.
      • Although the above factors help explain a portion of the increase in ASD prevalence overtime, approximately 50% of the increase is still due to unknown factors
      • While genetic susceptibility is likely involved in the majority of cases, it is believed that environmental factors play a role in autism susceptibility.
      • Autism Speaks has cast a wide net to explore the role of environmental factors, funding research on:
        • Parental age
        • Prenatal factors (e.g. maternal autoimmune response to fetus, maternal infections and medications, reproductive assistive technology, prematurity, birth complications)
        • Diet and nutrition (e.g., Vitamin D deficiency)
        • Postnatal challenges to the immune system, such as viruses and vaccines
        • Chemicals and toxins (e.g. pesticides)
  4. Are you funding research to better understand why these numbers are going up? What have you done since the last report?
  5. Disparities in diagnosis based on ethnicity… does this explain the increase?
    • While ethnic disparities in diagnosis alone cannot explain the increase in autism prevalence, improvement of autism detection in ethnic minorities may play a role.
    • From 2002-2008, the largest increases in prevalence were among Hispanic and non-Hispanic Black children, but the prevalence in non-Hispanic White children increased as well.
    • It is unclear whether differences in autism prevalence between ethnic groups, or the increase in prevalence among ethnic minorities, are due to differences in risk for autism or due to differences in access to appropriate diagnostic and intervention services.
  6. Does decreasing age of diagnosis explain the increase?
    • The average age of diagnosis has not changed much across ADDM data collection periods.
    • While there was an increase in the proportion of children that received an autism diagnosis by 36 months of age, the increase was modest and would not have a major impact on prevalence.
    • Autism can reliably diagnosed at 24 months and in some cases at 18 months, and early detection and intervention are critical to improving outcomes of individuals with autism.
  7. Differences in IQ of individuals diagnosed… Are we picking up milder cases and does that explain the increase? Are we seeing more extreme cases milder cases?
    • In general, ADDM is capturing more higher-functioning children. From 2002-2008, the largest increases in prevalence were among children with autism and borderline or with average/above-average intellectual ability, but the prevalence of children with autism and developmental disability increased as well.
    • The moderate increase in higher-functioning autism cases may only account for a small portion of the increase in prevalence over time.
    • Whether the increase is due to providers getting better at detecting higher-functioning autism or if it is truly becoming more prevalent is not clear.
  8. What are the implications of the DSM-5? – How will this affect prevalence?
    • It is unclear what the impact of DSM-5 will be on autism prevalence as existing research findings are limited.
    • The DSM-5 will do away with the subgroups of ASD defined in the DSM-IV. Instead, all persons on the spectrum will be given a diagnosis of ASD. Our concern is that the new criteria might end up excluding people who previously received a diagnosis. Published data thus far suggest that older and higher functioning individuals might be more likely to be excluded. We believe that more research needs to be conducted to definitively answer whether the DSM-5 will exclude people. Because this is a serious concern, we have responded by rapidly funding studies that will determine whether the DSM-5 is excluding people. If further research indicates that people are being excluded, we will advocate strongly for the DSM-5 criteria to be changed to address. The bottom line is that we want to ensure that no one struggling with autism is excluded from getting the services they need.
  9. What is Autism Speaks’ concern with the CDC funding?
    • The President has proposed funding CDC’s 2013 autism activities at $21.3 million, $700,000 below the authorized amount, within the Prevention and Public Health Fund, a funding stream created by the Affordable Care Act (ACA). The CDC’s autism funding is therefore at risk because of the overall reduction of the Prevention Fund, from $1.25 billion to $1.0 billion, to pay for a portion of the Medicare reimbursement fix (aka, the “Doctor’s Fix”) that passed in February 2012. Even if done proportionately, CDC’s autism funding could be reduced accordingly.
    • Those responsible for conceiving and authorizing the Prevention Fund never intended it to be used for existing public health programs. Ever since the Children’s Health Act of 2000 was signed by President Clinton authorizing the CDC to track autism surveillance, such activities have been funded within the core CDC budget. By moving this funding to the politically sensitive Prevention Fund, the Administration is putting critical dollars at risk at a time when it should be taking a lead on forming a national strategy to address the autism epidemic.