Study finds first direct evidence of a link between low serotonin and depression

Study finds first direct evidence of a link between low serotonin and depression

From the Guardian, science correspondent:

Link to the study:
BRAIN SEROTONIN RELEASE IS REDUCED IN PATIENTS WITH DEPRESSION: A [11C]Cimbi-36 PET STUDY WITH A D-AMPHETAMINE CHALLENGE.

 

Which is it?

A decreased serotonin response, in the brain, or a reduced capacity for releasing serotonin, in the brain, as as far as I know these are totally different things, but they seem to think they are the same.

and what about other sources of serotonin such as the gut?

 

I'm sure there's way more pieces to this puzzle than levels of chemicals.

 

90% of the body's serotonin is made and found in the gut. I wonder what effect (if any) anti-depressants have on the gut.

 

Blog critical of the study: https://eiko-fried.com/clear-evidence-for-serotonin-hypothesis-of-depression/

"Overall, sample size and generalizability are the reason why firm conclusions about e.g. “depression” only follow when 1) we draw a large sample from the population we are interested in, and 2) we draw a random sample of depressed patients.

In this particular study, neither is the case. The study has a very small sample size, and generalizability is very low because the depressed group is not representative of people with depression broadly. There are many factors here, but just to list one: 5 of the 17 depressed participants in the study (i.e. 30%) have Parkinsons disease, but this does of course not apply to the population of interest (not every third person with depression has also Parkinsons)."

 

So we're going to get both "no one took the serotonin hypothesis seriously in years" and "we've always known about the serotonin hypothesis" at the same time, uh? Because immediately after the paper people went out of their way to point out that no one has taken it seriously in years, even though it is basically all patients heard about because it sounded credible and sciencey.

And since the definition of depression has essentially become meaningless, who even knows what the patients being studied have in common. It seems even more heterogeneous and arbitrary than even the most generic concept of chronic fatigue.

Looking at it, I'm not even sure anymore which field of research is worse: ME or depression. It seems even more stuck in place and generic.

 

Note that if one outlier is removed from the results, they are no longer significant:

https://twitter.com/user/status/1588430405749059586

 

I don't think you even need to remove the outlier. You can see that those distributions are consistent with a single population by eyeball.

 

Wow is that figure from the paper?

Obviously not significantly different groups.

 

hmm
"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."
https://www.s4me.info/threads/the-s...w-of-the-evidence-moncrieff-et-al-2022.28687/

eta: surprised there is no definitive Cochrane review on this issue; only had a quick look on the Cochrane library.
@Caroline Struthers

 

There'd be money/prestige in proving they're linked --- opportunity for Cochrane!