Uh. Where did you hear about such test? Lately, the chemical imbalance has been more or less disapproved.

The truth is... we don't know what causes these problems, so to declare "I told him because of the chemical imbalance in the brain and that the meds can help with my thoughts, anxiety and moods.".... It's only partly true. Yes, meds may help. Because they are mind altering substances. So of course you will feel differently. Sometimes better, which is what is strived for. But as for now, we cannot say it is because we hit the magical "balance" of chemicals.

OP's brother might be asshole or maybe unknowledgable, but the OP should not just be trying this pill and that pill hope one will magically restore these "imbalances" and not try other ways and trying to work around what she has.

OP's brother seems to be falling for a duality that many people here fall for either "it is illness and chemical imbalance and only meds can help and person deserves sympathy" or "it is not illness and the person is just being dramatic and deserves no sympathy". As if one could not have emotional problems worth sympathy without it being some kind of "imbalance". (There indeed is no test for that, so I guess we all deserve to die in ditch if we think this way, eh).