How do you deal with a sibling who treats and talks to your mother like she is a child?

I am so frustrated. My 71-year-old brother talks to Mom (94) like she is a child (an octave higher than normal). If he is going out, he will say, "Is it okay if I go out for a little while??" (Translation -- he will be back the next day.) He constantly says to her, "You okay??" "I'll get that, hon." He refuses to let her do anything -- even pick up a piece of paper off the table to throw away. "Leave it, Mom. I'll get it." Or he will just move it out of her reach. He tells people that he has to do all the cooking now, and Mom can't do anything. Maybe now, Mom can't do much, but he started that when she was still capable. I also think she can throw things away if she wants. Someone may need to be behind her so that she doesn't fall. There are certainly things that can be done to keep her safe, yet feel like she can contribute to something. She is not an bedridden.

I tend to talk to Mom in a firm voice when I want her (or I don't want her) to do something. (Like not get up from her chair because she might fall.) I don't want her to get hurt (as she has a number of times). I will admit that sometimes (after being with her 12 hours a day), I do get frustrated. But, the only thing Mom has listened to in the past is when we raise our voices. She told me that she cannot go down the basement anymore because she would get hollered at.

Earlier today, My brother left the room for a few minutes, and Mom fell (I was in the next room getting her something to drink). When he heard her fall, he ran into the room and started crying. I picked Mom up and explained to her that she has to stay in her chair until someone is there to help her. He tells me, "She doesn't know what she is doing." I disagree. She didn't see anyone in the room, and she wanted to see where everyone was. After that, she asked for help to get up because she was afraid of falling. The next time, she tried to get up and told me she wanted to do it herself. She thinks because she fell one time, maybe this next time she won't. She has always been independent. But, she also thinks she in invincible.

After the fall, my brother said I needed to calm down (I was frustrated), yet he talks to her like she is a child (a completely different personality than he used to have...which is curious in itself...) He says he and I handle things differently. I tend to pick my battles with her (and making sure she doesn't fall is one of them). I told him that talking to her like a child isn't working either. I read on this site that even if an elderly person has dementia, you don't talk to them like a child. I am at my wits end because I know he doesn't get it, and he gets defensive if you try to explain it to him.

Venting....