I wouldn’t rule it out entirely as it has different sources, some medical, some spiritual, and some environmental/trauma factors.
These 2 accounts are obviously people who would get a mental health diagnoses today…whether SZ or something else…point is they are cured by faith…
15 Lord, have mercy on my son: for he is lunatick, and sore vexed: for ofttimes he falleth into the fire, and oft into the water.
16 And I brought him to thy disciples, and they could not cure him.
17 Then Jesus answered and said, O faithless and perverse generation, how long shall I be with you? how long shall I suffer you? bring him hither to me.
18 And Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour.
19 Then came the disciples to Jesus apart, and said, Why could not we cast him out?
20 And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.
This next dude would surely be committed and injected with Haldol today for those type of actions.
2 And when he was come out of the ship, immediately there met him out of the tombs a man with an unclean spirit,
3 Who had his dwelling among the tombs; and no man could bind him, no, not with chains:
4 Because that he had been often bound with fetters and chains, and the chains had been plucked asunder by him, and the fetters broken in pieces: neither could any man tame him.
5 And always, night and day, he was in the mountains, and in the tombs, crying, and cutting himself with stones.
6 But when he saw Jesus afar off, he ran and worshipped him,
7 And cried with a loud voice, and said, What have I to do with thee, Jesus, thou Son of the most high God? I adjure thee by God, that thou torment me not.
8 For he said unto him, Come out of the man, thou unclean spirit.
9 And he asked him, What is thy name? And he answered, saying, My name is Legion: for we are many.
10 And he besought him much that he would not send them away out of the country.
11 Now there was there nigh unto the mountains a great herd of swine feeding.
12 And all the devils besought him, saying, Send us into the swine, that we may enter into them.
13 And forthwith Jesus gave them leave. And the unclean spirits went out, and entered into the swine: and the herd ran violently down a steep place into the sea, (they were about two thousand;) and were choked in the sea.