It is possible that some students know what drugs are and are not included in the tests, and migrate toward using those not included.

What is significant is that the use of these substances has declined substantially since the recent peak levels reached in the mid-1990s.

Most declines halted this year.

Eighth-graders tend to be the first ones to show new trends. Most are blank slates and haven't developed habits and are more sensitive to environmental changes. As these eighth graders move up the age spectrum, the high school teenage smoking trends will follow.

There is some logic to that, because if you're buying Ecstasy, you have no idea where it was made or what's in it.

We're also seeing an increase in the use of these drugs in young adults.