Question: when were any truly new drugs to treat depression last developed? Five years ago? Twenty years ago? Or more than 50 years ago?

Answer: the third one. For the last half-century, doctors have been prescribing antidepressants, which despite differing brand names and refinements over the years, mostly work in roughly the same way.

In theory, they target the brain’s chemical system: serotonin and noradrenaline are the chemical messengers or neurotransmitters that are most often referenced in the scientific literature. Exactly how these drugs work, and how much they work, is disputed.