They do occasionally talk about such substances, however, such as when they try to guess what the latest patient is addicted to. Not knowing that Cornell is her counselor, Gwen asks him if there's any way to get something at the rehab center with a little more kick than cigarettes. Gwen has some flashbacks to her drinking and partying with others as well as her mother being drunk or passed out when she and Lily were just young girls. Jasper brings some champagne on a rowboat for him and Gwen, but she throws it overboard. A patient dies from a drug overdose of heroin or something similar they injected.
People have drinks in a bar.
We hear Gwen vomiting into a toilet. During a lecture, a jar containing pieces of a liver is passed around while a photographic slide shows a diseased photo of the same. We see a bloody slice on Andrea's leg from where she purposefully cut herself. Casper has a little bit of blood running from his nose after being punched. Gwen is initially condescending toward the other patients and staff at the rehab center.