wait, IS this One Flew Over the Cukoo's Nest or is it BASED on it?

Because there does seem like there are many similarities, but it doesn't nessecarily mean that this movie is a teenage version of it.
Similarities:
1. A new wild patient gets admitted to a psychiatric ward.
2. A quiet Native American befriends the main character.
3. Main character refuses to believe he's crazy.

There are more but it stil seems like it could be just a coinsedence. Does anyone know for sure?