The word 'lunatick' (KJV)is defined in Strong's as 'crazy', but in NKJV, NIV, ASV it is translated as epileptic. Anyone know any more about this word?
Interestingly, the only other time it is used is in Matthew 17:15 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. (KJV)
Here, Jesus goes on to rebuke the devil (a demon, NKJ) from the child
Matt 17:18 And Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour. (KJV)
Seems like madness CAN be caused by demons. (unless it was epilepsy, in which case, there was a demonic influence present, at least for this child. Don't know if we can imply that all madness or all epilepsy is demonic)

Here's a couple of other verses on madness...
sometimes the Lord Himself strikes people with madness:
Deut 28:15 "But it shall come to pass, if you do not obey the voice of the LORD your God, to observe carefully all His commandments and His statutes which I command you today, that all these curses will come upon you and overtake you:
Deut 28:28 "The LORD will strike you with madness and blindness and confusion of heart. (NKJ)

And again:
Zech 12:4 "In that day," says the LORD, "I will strike every horse with confusion, and its rider with madness; I will open My eyes on the house of Judah, and will strike every horse of the peoples with blindness. (NKJ)
Nebuchadnezzar went mad for a time, but it doesn't say anything about it being caused by the devil. In fact, the chapter closes with a pretty strong hint that the Lord was responsible.
Dan 4:37 Now I, Nebuchadnezzar, praise and extol and honor the King of heaven, all of whose works are truth, and His ways justice. And those who walk in pride He is able to put down. (NKJ)
Maybe we'd say King Saul was crazy.
1 Sam 16:14 But the Spirit of the LORD departed from Saul, and an evil spirit from the LORD troubled him. (KJV)
Now what was that? An evil spirit from the Lord??? What is an evil spirit from the Lord?