My brother is genuinely convinced that our mom is trying to kill him. No joke, he thinks she's on the prowl and wants him dead.

She has never made any violent advancements towards him in his entire 19 years of life. He's always been a bit of a problem child but now he's convinced she's the root of it all and that her final actions is gonna be to kill him in his sleep.

How can I convince his retarded ass that he needs to get a grip? He's also a raging furry, if that affects anything.