Well......
All I can say is that I had monitoring software on difficult child's computer (before she was 18), and what I saw there was what led me to the conclusion, verified five years later, that she was bipolar. She was a completely different person at school and in front of familiy members. Behind that facade, lurked a very disturbed difficult child.
Since she was able to keep up her grades and continue to perform, it is likely that this young lady is not abusing drugs. But it is very possible that there is mental illness there.
Nevertheless, her parents tactics were conterproductive (to say the least), damaging, and just plain wrong.
Dash