My brother gets really depressed about his life?

Hes been diagnosed with anxiety snd depression. We constantly try to help him but he does nothing to help himself. He just watched cartoons or uploads vids to his youtube channel which is wuite popular. He doednt study at all but then freaks out and gets all depressed when he has a test and at times at all costs tries to avoid taking it. On top of that, he dowsnt even prepare for his SATs. Im lucky because im "naturally smart". I underdtand where his laziness comes from. But i really try to talk to him on a doen to earth level. Its like he knows he has to put in work but he doubts himself, doesnt think he can handle college, and my mom just keeps pushing him because she has this dream where all of us go to college and become doctors/lawyers. My dad understand my bro to some extwnt is full of crap but he wants him to know he has to work to achieve things. My bro doesnt do anything and gets all depressed like living wasnt meant for him when nothing good comes his way.