Consider the recent NBER working paper by Finkelstein, Gentzkow, and William (2019). They find that peer effects are real in the case of opioid abuse:
… movement to a county with a 20 percent higher rate of opioid abuse (equivalent to a move from a 25th to 75th percentile county) increases rates of opioid abuse by 4.5 percent, suggesting that roughly 20 percent of the gap between these areas is due to place-specific factors. These effects are particularly pronounced for prior opioid users, who experience an increase in opioid abuse nearly 1.5 times larger than the increase for opioid naives.
- Finkelstein A, Gentzkow M, Williams H. What drives prescription opioid abuse? Evidence from migration. Stanford Institute for Economic Policy Research Working Paper. 2018 Aug:18-028.