Over the past couple of decades, we have seen a big increase in neurotransmitter dysfunction ranging from anxiety and depression, to Alzheimer's and even Schizophrenia. The 4 main neurotransmitters that we pay attention to are:

Serotonin
GABA
Catecholamines
Endorphins
There has been a lot of information coming out about the power of the Ketogenic Diet for optimal brain function, but that relates mostly to the brain cells using ketones as the primary fuel source compared to glucose. What we don't hear about often enough is the types of amino acids needed to produce neurotransmitters.