Depleting brain serotonin with large doses of branched-chain amino acids leads to impulsivity, reduced planning and memory, anxiety, depression, impaired facial expression interpretation, and reduced sensory gating.

“where they've taken normal people and depleted their serotonin by giving them a shake of Branch chain amino acids like Lucine and isol leucine which out compete tryptophan to be transported into the brain so what happens is after you give someone a big Shake of these branching amino acids without tryptophan their tryptophan levels drop in their brain and subsequently their serotonin levels drop by about 90% And what happens is people become very impulsive their short-term uh thing their short-term gratification kicks in their long-term uh planning and memory the long-term functions they shut down they go for the instant gratification uh people become anxious depressed their mood changes they have a hard time um interpreting facial expressions of anger or happiness which is related to empathy um they also become a little bit more impulse aggressive as well um so you know and in addition they're sensory gating so the ability to filter out you know different auditory and visual stimuli and just focus in on one thing that's also um changes and that they have problems with that which is very relevant for schizophrenia and ADHD”