One upcoming data point that will be interesting to know is the depression levels of LWers. A question about depression, and other mental issues, has been asked to be included in the upcoming Massive LW Survey Of Doom. I actually expect that, not only will we have higher levels of Asperger's than the base rate, but that we will also have higher levels of depression.

I have read (sorry, don't remember where) that rational people are more likely to have depression, because the cognitive biases (specifically ones about how awesome you are) that protect most people are not as active. And that females who are also rational are extremely likely to have some depressive issues. It will be interesting to see if the LW survey supports this.