Comment by bravetraveler

At a certain point one is "maintaining 0". High is "not on the floor writhing or worse."

That said, there can be signs. You may find them normalized from exposure. Or, perhaps: hidden, your cousin maintained appearances. With time and circumstance, everyone slips. Sometimes it's seen.

My (much older) brother managed his addiction, and appearances, well at work for decades. Now clean, thank goodness.