I'm willing to bet that Tyce and Jace are self-medicating with drugs due to their mental and emotional problems. It's pretty common for people with depression, bi-polar disorder, psychosis, schizophrenia and so on to use illicit drugs or take more than the therapeutic dose of prescription drugs to self-medicate. I've done it before myself to cope with my bi-polar. This doesn't mean that they are addicted to anything, but it doesn't rule it out either. But I think they fall more into the line of "My life sucks, I'm depressed, I'm bored, so I'm going to take these pills/drink this booze/smoke this weed/sniff this glue/huff this jenk to feel good". It's an escape for them, much like Jace uses gaming to escape from the real world. The problem is escapism isn't dealing with the problems, so they never go away and can actually become worse, as with Jace's delusions getting worse lately. He can't tell reality from his delusions anymore.