University, psilocybin was shown to alleviate anxiety and
increase feelings of life satisfaction in patients with life-
threatening cancer for six months after just a single dose.^16
The cognitive-enhancing potential of low doses of
psilocybin, called micro-dosing, is currently being studied.
Serotonin isn’t just for good vibes. It’s also heavily
involved in executive function. We know this because
scientists have devised a clever way of temporarily reducing
levels of serotonin in people, and the results aren’t pretty.
As I’ve mentioned, serotonin is synthesized in the brain
from the essential amino acid tryptophan. The tryptophan
we consume in protein makes its way up to the brain, where
it then has to be carried across the blood-brain barrier by
transporters. Other amino acids vie for these same
transporters, including branched-chain amino acids, which
are important for brain function and muscle growth, among
other things. When given as a standalone supplement, these
amino acids can outcompete tryptophan, blocking its entry
into the brain.^17 (One of the ways exercise actually boosts
your mood is by causing your muscles to “suck up”
circulating branched-chain amino acids, thus allowing
tryptophan easier entry into the brain—more on this in a
moment.)
So, what happened when scientists gave these amino
acids to subjects? Serotonin levels temporarily plummeted.
This was accompanied by a wide range of behavioral
changes including increased aggression, impaired learning
and memory, poorer impulse control, a reduced ability to
resist short-term gratification, impaired long-term planning,