Showing posts with label Autism. Show all posts
Showing posts with label Autism. Show all posts
Tuesday, August 27, 2013
Thursday, May 05, 2011
Autism epidemic? More likely we're just better at diagnosis
From: Ars Technica
In the developed world, rates of autism spectrum diagnoses have skyrocketed in recent years, raising the specter that a new environmental factor has been altering the developmental trajectory of the youngest children. Searches for putative environmental influences, however, have generally come up empty, even as researchers have identified very strong genetic influence on the disorders. The disparate rates of progress provide some support for an alternate interpretation: autism has always been around at roughly this level; we've just gotten much better at diagnosing it.
A study in the UK now provides a bit more support for this argument. Researchers have performed a large-scale survey of adults, looking for indications of autism spectrum disorders where none had ever been diagnosed. And they found cases, enough to suggest that the rates haven't changed considerably.
The report starts out by describing the evidence for a rising tide of autism spectrum disorders (ASDs). Surveys prior to the 1990s had indicated an incidence of about 4.4 cases per 10,000 individuals. By the '90s, that rate had risen to 12.7, and more recent surveys suggest an incidence of 10 per every 1,000, or roughly one percent. This startling rise, if it's real, suggests a recent uptick in an environmental exposure is altering neural development in early childhood.
Based on that suggestion, the British team started with a few simple hypotheses. If the prevalence of ASDs has been increasing, then the youngest adults would have rates similar to the ones seen in the oldest children, with the rates dropping with age. They also hypothesized that any adults they did find would share features with the other ASD individuals, including poor social integration; like the current generation, they'd be more likely to be male.
In the developed world, rates of autism spectrum diagnoses have skyrocketed in recent years, raising the specter that a new environmental factor has been altering the developmental trajectory of the youngest children. Searches for putative environmental influences, however, have generally come up empty, even as researchers have identified very strong genetic influence on the disorders. The disparate rates of progress provide some support for an alternate interpretation: autism has always been around at roughly this level; we've just gotten much better at diagnosing it.
A study in the UK now provides a bit more support for this argument. Researchers have performed a large-scale survey of adults, looking for indications of autism spectrum disorders where none had ever been diagnosed. And they found cases, enough to suggest that the rates haven't changed considerably.
The report starts out by describing the evidence for a rising tide of autism spectrum disorders (ASDs). Surveys prior to the 1990s had indicated an incidence of about 4.4 cases per 10,000 individuals. By the '90s, that rate had risen to 12.7, and more recent surveys suggest an incidence of 10 per every 1,000, or roughly one percent. This startling rise, if it's real, suggests a recent uptick in an environmental exposure is altering neural development in early childhood.
Based on that suggestion, the British team started with a few simple hypotheses. If the prevalence of ASDs has been increasing, then the youngest adults would have rates similar to the ones seen in the oldest children, with the rates dropping with age. They also hypothesized that any adults they did find would share features with the other ASD individuals, including poor social integration; like the current generation, they'd be more likely to be male.
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