- An increased prevalence of various conditions including autism, ADHD and developmental delays for children aged 3-17 years between 1997 and 2008.
- Prevalence of these conditions increased from 12.8% (~8 million children) in 1997-1999 to 15% (~10 million children) in 2006-2008.
- Prevalence of reported ADHD increased from 5.7% (1997-1999) to 7.6% (2006-2008).
- Prevalence of reported autism increased from 0.19% (1997-1999) to 0.74% (2006-2008).
- Lower income was associated with a higher prevalence of a developmental disability.
- Hispanic children had the lowest prevalence of developmental disability (compared with non-Hispanic white or black children).
Bearing all this in mind, it is worthwhile pointing out that the data was derived from the US National Health Interview Survey. Similar methods of data collection have been reported previously for autism, where results from 2003-2004 for children aged 4-17 years suggested a prevalence rate of 0.57%. This would tend to fit with the data provided by the new study based on the dates studied. Previous results for prevalence of ADHD and ADHD-type symptoms can be viewed here. The finding that lower income was associated with a higher prevalence is an interesting one and kinda coincides with some of the discussions in this previous post looking at SES and autism following the recent King and Bearman paper. A reversal of the negative socio-economic status health gradient? The authors apparently have suggested lots of reasons for the increase in cases: better awareness, better screening and assessment facilities, etc. They also suggest that increasing parental age might be a factor alongside an increase in preterm births. Preterm births are something that have been examined using the same methodology - particularly birth weights - and found to present with a relationship (albeit not straightforward) with 'disability' prevalence.
So in May 2011 alone we have had 1 in 100 adults with an autism spectrum condition in the UK, 1 in 77 children with autism in Utah, 1 in 38 children with autism in South Korea and now this. Quite a month I'm sure you will admit. The question is what do we do next?