What type of antidepressant was the first class developed?

The first class of antidepressants developed were the monoamine oxidase inhibitors (MAOIs). Introduced in the 1950s, MAOIs were found to be effective in treating depression by inhibiting the activity of the enzyme monoamine oxidase, which is responsible for breaking down neurotransmitters such as serotonin, norepinephrine, and dopamine. By preventing the breakdown of these neurotransmitters, MAOIs increase their levels in the brain, which can help alleviate symptoms of depression.

This historical context is important, as it sets the stage for the subsequent development of other classes of antidepressants, such as tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs). TCAs, while introduced shortly afterward, and SSRIs, developed later, represent advancements in understanding depression and pharmacotherapy but were not the pioneering class. Therefore, the identification of MAOIs as the first class reflects their foundational role in psychopharmacology for depression.