[0xcde4c3db]

I skimmed the literature a bit, and the results on this seem to be pretty mixed. Basically, exercise boosts serum BDNF, except when it doesn't. In particular, it doesn't seem to be clear what the necessary conditions are for a sustained effect on BDNF, as opposed to a previously sedentary/untrained person getting a transient boost from a single bout of exercise. One study's [1] introduction summarized it thus (a lot of parenthetical citations removed for brevity/readability):

> Animal studies have implicated the neurotrophin BDNF and the growth factor IGF‐1 in mediating the beneficial effects of exercise on hippocampal function and structure as well as cognition. In humans, findings are less clear since exercise‐induced increases in peripheral BDNF have been consistently shown only immediately after a single bout of aerobic exercise. Studies involving longer exercise interventions (i.e., 6 weeks up to 1 year) have reported mixed results. While the majority of reports have found no changes in circulating BDNF and IGF‐1 at the end of the training period, Zoladz and colleagues (2008) demonstrated increased plasma BDNF after 5 weeks of endurance training in physically active male adults. Further, Leckie et al. (2014) found that 1 year of moderate‐intensity walking significantly elevated serum BDNF only in individuals older than 65 years of age. Lastly, Heisz et al. (2017) reported that, although no group differences in serum BDNF were found following 6 weeks of high‐intensity interval training in young adults, participants with greater fitness improvements had higher serum BDNF levels than their counterparts with lower fitness gains.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6555846/

[fny]

The LSD study captures the same effect actually. There is no sustained BDNF increase outside the 6 hour window they measured. In fact, it's seems as if the BDNF is entirely eliminated at the end of the 6 hours.

From this, I'd guess one wouldn't see a sustained increase in BDNF levels from microdosing either.

[nullc]

So why assume that studies of drugs have better technique? It's a lot easier to study exercise.

I think a lot of X correlates with Y studies are just kinda crap for a number of reasons, including that we don't have extremely good baselines -- e.g. continuous 24 hour monitoring across a wide population in a multitude of circumstances.

[0xcde4c3db]

I don't think we should make any such assumption. What this looks like to me is that researchers have seen a couple different ways to trigger something that might be the same mechanism, but the overall way it works is still enough of a mystery that it's hard to say what the overlap is.