> If you could elaborate on the topic it would be really great, I know so many people who blame everything in their life, most of all their lack of discipline with, oohhhhh my brain needs dopamine, i just need that doppaamine, and serotonin, you can increase it by bla bla talking about the brain like it is an engine that runs on oil gas, sparks and timing.

aiui (someone who knows more please correct me if I'm wrong):

It's not as simple as "my brain lacks serotonin -> I am depressed" or similar, because neurotransmitters are just that -- something that moves some message around the body. ~90% of bodily serotonin is used in the GI system, ~8% in platelets, and the rest in the CNS[0]. Since it's one of the primary neurotransmitters, it affects an enormous number of systems in the body: Memory, learning, anxiety, pain, depression, vision (and hallucinations; psychedelics bind to serotonin-2A), vasoconstriction, bone mass, heart function, vomiting, food moving through the GI system, and a LOT of other functions[1].

It's why psychoactive drugs work with such broad effects:

- Cannabis has memory-altering effects because of indirect action on serotonin receptors via the cannabinoid receptors[2]

- Psychedelics bind to serotonin-2A to produce the primary effects

- MDMA binds to the serotonin transporter (among other things) as a reuptake inhibitor, and also causes the brain to release serotonin. MDMA also indirectly stimulates a lot of receptors[3], so it's not as simple as "MDMA -> serotonin release / reuptake inhibition -> happy :D" or similar.

There's also some fairly recent research[4] that the serotonin model of depression might be wrong:

> The main areas of serotonin research provide no consistent evidence of there being an association between serotonin and depression, and no support for the hypothesis that depression is caused by lowered serotonin activity or concentrations. Some evidence was consistent with the possibility that long-term antidepressant use reduces serotonin concentration.

Many antidepressants also act on receptors other than serotonin receptors, ex. Bupropion[6] is a norepinephrine–dopamine reuptake inhibitor and doesn't touch serotonin at all. This isn't to say that serotonin activity plays no role in depression etc., but rather that it's a part of a very complicated picture.

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I imagine that the "confusion" around the topic is caused by something like:

- Researchers in the 50-60s[5] think serotonin might have smth to do with depression

- Medications that affect serotonin seem to work, so we go with it

- We get to more-modern times, where the internet is fairly commonplace

- People are prescribed SSRIs or similar for depression

- People are told SSRIs increase levels of serotonin in the brain

- This gets turned into "depression caused by low serotonin"

- We are here

[0] https://en.wikipedia.org/wiki/Serotonin

[1] https://en.wikipedia.org/wiki/Serotonin#Serotonylation See table below heading

[2] https://journals.plos.org/plosbiology/article?id=10.1371/jou...

[3] https://en.wikipedia.org/wiki/MDMA#Receptor_binding

[4] https://www.nature.com/articles/s41380-022-01661-0

[5] https://www.menningerclinic.org/news-resources/serotonin-the... Please note I am only using this as a date reference

[6] https://en.wikipedia.org/wiki/Bupropion#Pharmacology