Sometimes, students who are overly concerned about getting good grades are under tremendous pressure. Pay special attention to students who can't make it to earlymorning classes, or who always cut the classes after lunch. Often, students who play the class clown, who are disruptive, or who command all of your attention are masking real emotional pain. Students who keep getting in trouble may, in fact, be troubled. If you have repeatedly thrown a student out of class, and it doesn't seem to be getting you anywhere, try a referral to the SAP as well.
Many legal difficulties begin or are exacerbated by alcohol and other drug use.
Angry students who are troubled often work out their anger by rebelling. Such declining interest may signal trouble. Often, there are other students who are dealing with the same issues, and your student can be reassured by speaking with them. The student may be giving you that information in the hopes that you'll respond. Stake your bets.