Alexander Morison's Top Hat

Origin
Sir Alexander Morison M.D. (1779 - 1866) was a Scottish physician and psychiatrist. After becoming a doctor in 1799 he became a licentiate of the Edinburgh College of Physicians in 1800 and a Fellow in 1801. After practicing medicine for regular people and royalty alike he began treating those hospitalized in lunatic asylums in Surrey to study mental diseases. Morison's most historically important piece of work was The Physiognomy of Mental Diseases where he delved into the minds of the mentally unstable. One of the primary focuses of the book was Jonathan Martin the arsonist who set fire to York Minster.

Effects
Causes diagnoses made by the wearer to become true. For example, if they diagnose a person with a disorder or disease in a person who doesn't have it, they will suddenly obtain the aforementioned disease or disorder.