A 21-year-old woman presents to the clinic with severely depressed mood for the past five days. Her mother adds that earlier this month she became hyperactive, with rapid speech, expansive mood, a flight of ideas, and insomnia that lasted four weeks, necessitating a leave of absence from college. She takes no medications, has a negative urine drug screen, and does not use drugs. Which of the following is the most likely diagnosis?
Bipolar I disorder
Bipolar II disorder
Cyclothymia
Major depressive disorder