The Dragon 18

Dragon magazine 18 was released in September 1978.

Insanity, or Why is My Character Eating Leaves?

 * By Kevin Thompson.

This article gives 1st edition Dungeons & Dragons rules for developing rules for adding insanity into your game. Thompson has a nice chart for insanity saving throwing and creating madness behaviors, such as gibbering, catatonic, and kleptomaniac.