Good morning. Thanks for writing to JA.
Please understand, first of all, that it's inappropriate and unethical to diagnose over the internet. So - I can't confirm that your brother has an "antisocial disorder." There is such a thing as Antisocial Personality Disorder (also called Sociopathy), but from what you describe, I might suspect something else... it sounds like, rather than being ANTI-social, your brother may be A-social.
That is, anti-social behavior refers to a person knows what is considered socially appropriate and either intentionally does the opposite of unintentionally does the opposite, but feels absolutely no remorse about it. Antisocial behavior really also refers to behavior that hurts others or violates the rights of others (criminal activity, theft, rape, murder). Being a "jerk" doesn't mean he's antisocial, it may just mean that he's "clueless."
Asocial behavior refers to a person who just simply doesn't know or care what is socially appropriate. These folks don't intentionally do anything with regard to social expectations - meaning that they don't violate the rights of others or hurt other people (again, at least not intentionally). They, literally, don't understand how their behavior impacts others. Your description of the "Oh, right" kind of response suggests (a) that he's heard what is socially appropriate - and (when reminded) can recognize his own behavior and (b) there might be even a mild sense of embarrassment or remorse when he messes up. This pretty much rules out an Antisocial Personality Disorder.
Folks like this (asocial) don't really fit into any category or "diagnosis." (That is, being a "jerk" doesn't necessarily make you mentally disordered.) There are several diagnoses that *might* be appropriate - such as Asperger's Disorder, Nonverbal Learning Disorder, Attention Deficit Hyperactivity Disorder, etc... - but these are probably a stretch and, again, we don't diagnose a 3rd party over the internet.
Since it's unlikely that you'll be able to get him into treatment, another option for you to consider is to get YOURSELF into treatment to learn how to deal with his obnoxious behavior. It's also possible to see a family therapist - who can work with ALL members of a family - including brothers! What really needs to happen is a system of communication between you that works and prevents (a) his obnoxious behavior and (b) you losing your patience and blowing your top.
I hope this was helpful. Best of luck to you both!
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