"I'm a mother of a teenager son. He seems to have developed an aggressive attitude as of late. Also, he seems hyper and agitated most of the time. Is that a sign of smoking marijuana?"
The change you're most likely to see (if he is smoking pot) is that your son will appear slowed down and dull. The change is subtle, though, so it's really only noticeable because you're familiar with what's normal for your son. Also, a pot smoker may or may not have wet, red eyes, but the real giveaway is his breath. The smell will clue you in every time.
I don't want anything I say to reduce your suspicions, however. Every parent of American teenagers needs to be suspicious about drug use. The time to talk to your teens about drugs is before you notice any behavioral changes. So, for you, it's time to get started. Rather than focusing on "is it this" or "is it that," talk to your son about what he is dealing with in his life right now.
My Out-of-Control Teen: Help for Parents