Syphilis is a sexually transmitted disease that can destroy brain cells resulting in madness.

At the time Bronzino painted this picture, mercury  was used in the treatment of syphilis.

Mercury is itself poisonous and had the unfortunate side effect of turning the sufferer's skin green!

Could this be a syphilis sufferer?....

...or could this person be tormented by a different problem?

What does the tormented person represent?