Some drugs, like acetominophen (tylenol), are considered "safe" when they are fundamentally quite toxic.
Others, like Ritalin, are properly regarded with great suspicion. How can such a powerful medication be safe for decades of use in a developing brain?
Surprisingly, the literature is reassuring. I can now add some informal updates courtesy of a family member who does NIH funded research in this domain. The research community has long expected ritalin to have some deleterious effect on neuronal proliferation, but recently concluded studies, and those still in progress, will likely show (again) surprisingly negative results. Probably Ritalin has some effect on brain development, but the effect size is small.
Hard to believe really, but it does affirm my prejudice in favor of this well aged medication. Given Ritalin's safety record, it would take a lot to make me shift to another medication of the same or similar class.