Antidepressants are medications used to treat depression. Depression is a mood disorder distinguished by feelings of sadness and a loss of interest in objects and activities. Antidepressants were developed in 1950. Depression can also impair cognition, memory, sleep, appetite, and motivation. Antidepressants are generally useful for treating moderate, severe, and chronic depression. Antidepressants are typically given in the form of tablets. In general, these are prescribed at the lowest possible dosage of the medication.