Serotinin absolutely does have an impact. But here's the kicker, a majority of it is produced in the gut. Poor guy health impacts serotinin production, which can impact melatonin production. Intestinal parasites can deplete serotinin. Docs prescribe SSRIs, boosting serotinin. It works for a period of time until it doesn't…cuz parasites.
Ivermectin and Fenbendazole are known to eliminate depression and anxiety. Happens rapidly in many cases. Why?