How much alcohol must an adolescent have to consume to cause permanent brain damage or developmental problems?

Individual Levels: There is no one answer to this, since each individual is different. However, teenagers should not drink alcohol for a very good reason: their brains are still developing. If you add toxins (e.g., alcohol, nicotine from cigarettes, etc.) to a growing brain, you're only doing it harm.

Depends: Define cause. Directly it would have a variable effect depending on metabolism.I have seen one teen episode with the kid in a stupor & suppressed ventilation to the point the kid forgot to breathe.An observant pal & night in the ICU kept him alive but with mild brain damage. After a few drinks & sudden encounter with a tree, brain damage can be the result of a secondary event, the crash.