Problem: Local law enforcement transports a patient to your emergency room for evaluation following his bizarre behavior in public. By the time you have the opportunity to see him, it is several hours later. He's been seen by the ER doctor and given a mood stabilizer and a sedative. After reading the physician's note and talking with him, it's clear the patient was displaying manic behavior that meet all the criteria for diagnosis of manic episode and bipolar I disorder EXCEPT that symptoms have only been going for a few days. The patient has had a depressive episode a few months ago but no other concerns. What is the correct diagnosis in this instance and why?