Monoamine oxidase inhibitors (MAOIs) were introduced in the early 1950s. These antidepressants strongly increase serotonin, norepinephrine, and dopamine in the depressed brain; perhaps this is why MAOIs work so well.
Monoamine oxidase (MAO) is the brain enzyme that disposes of extra serotonin, norepinephrine, and dopamine so they do not build up in the brain. In depressed individuals, whose brain cells have been damaged by stress, MAO breaks down so much serotonin, norepinephrine, and dopamine that there is not enough to allow brain cells to fire normally. MAO inhibitors (MAOIs) block this enzyme so that more serotonin, norepinephrine, and dopamine are available to your brain cells and they can again carry signals through your brain. Many doctors consider some of the monoamine oxidase inhibitors to be the best antidepressants ever marketed.
MAOIs also reverse some of the natural changes of aging in the brain. Can MAOIs keep your brain young? We do not yet know the answer, but it is an interesting possibility.