Substance Abuse and Therapy Boundaries

Thank you for your post.  It sounds like you're very concerned for your brother.  It is not uncommon for individuals diagnosed with Bipolar Disorder to self medicate with substances such as marijuana.  In fact, substance abuse makes it quite difficult to diagnose many disorders because they can mask the symptoms.

Your concern is about patient doctor confidentiality boundaries.  You are in a complicated scenario because although you want your brother to receive the care he needs, this is something he needs to want for himself.  Even if you do call his psychiatrist, his psychiatrist cannot legally or ethically confirm he is a patient.  Additionally, your brother's treatment is exactly that.  It is HIS treatment.  If he wants to waste time by providing inaccurate information that may or may not hinder treatment, that is his choice.  Additionally, if his psychiatrist finds out about his substance abuse, there is no guarantee that your brother will then be on board for treatment.  

I understand that you have your brother's best interest in mind, but consider what this will do to your relationship with him in the long run.  He likely won't want to discuss anything else with you, let alone disclose anything that he wants to be remain confidential.  Although it's painful you need to wait for your brother to be committed to his treatment.  You'll know this has happened when he begins to take treatment seriously and he begins to address his substance abuse problem.  If you want to do something that might impact him, I would suggest you two attend a substance abuse recovery group.  There are groups similar to Alcoholics Anonymous that exist for marijuana that you can easily google in your immediate area.  Good luck to you and your brother.  I wish you both the best.