Mad Hatter’s disease
a condition caused by chronic mercury poisoning and characterized by changes in mental status, emotional disturbance, gastrointestinal disturbances, and weakness or partial paralysis of the legs. The condition may also cause psychosis, behavioral changes, erethism, and several other symptoms. The name derives from the prevalence of this condition among hatters whose occupation, until the mid-20th century, exposed them to vapors from the mercury used to treat felt for hats. Also called Mad Hatter’s syndrome.