Monomania is an intense, obsessive focus on a single idea, subject, or impulse, historically viewed as a form of partial insanity in 19th-century psychiatry, now often seen as extreme obsession or craze where other aspects of life are neglected. Symptoms include consuming preoccupation, irrational behavior related to the obsession, and neglect of self/others, stemming from excessive interest or even uncontrollable urges.