i will start with dr. hurd. the record.his into it is really a question for nih. as i was listening to testimony, it occurred to me it would be useful to understand whether the prevalence of alzheimer's is increasing, or is that just a factor of us living longer? i don't know the answer to that. i assume it has significant consequences. are you expecting greater cost in the future as a result of longevity? scientifically, on a research basis, has alzheimer's been with us to the degree it is today in the past, but now that we live longer, therefore -- it's not that we are physiologically changing, just we live longer and the evidence exists? i don't know if that's a question for you or not. but before i forget my question, i wanted to make sure i got it. >> i can say something about it. to see ifin our data we saw any trend or prevalence adjusted for age. you are exactly right. one needs to be quite careful about increased dementia due to increases in aging of the inulation from changes dementia prevalence holding age constant. a veryter would be important finding,