Allen drives Mom and Susannah to the psychiatrist, Dr. Sarah Levin. Susannah is excited to see her, both to confirm her bipolar self-diagnosis and because she finds psychiatric visits entertaining after watching the HBO show In Treatment. When Dr. Levin invites Susannah into her office, she takes a Polaroid photo of Susannah. Sarah asks Susannah why she's come, and Susannah explains that she's bipolar. When asked to explain why she thinks that, Susannah makes her case through logic that's hard to follow. Dr. Levin finally diagnoses Susannah with a "mixed episode," meaning that she's experiencing both manic and depressive symptoms. She writes Susannah a prescription for a medication to treat mood and thought disorders.
Bringing up her thoughts about In Treatment shows that Susannah doesn't exactly take psychiatry seriously yet—she finds it mostly entertaining. Susannah's jumpy and hard-to-follow logic suggests that there's something going on that's making it difficult for her to make coherent connections between ideas. It's important to keep this in mind, as Dr. Levin diagnoses Susannah with a mental health disorder and doesn't even suggest that there might be something physiological going on as well.
While Susannah is with Dr. Levin, Mom calls Susannah's younger brother, James. She explains what's going on with Susannah and asks James his opinion on Susannah's drinking. James insists Susannah can't be an alcoholic, and he also doesn't buy the bipolar disorder diagnosis. Mom admits that she doesn't believe the diagnosis either.
This conversation highlights the importance of thinking critically about what doctors say, and not just blindly trusting them. This critical thinking on Mom's part is what will eventually help Susannah get the medical attention she needs.