Just FYI, the acetyl-L-carnitine is metabolized to carnitine which is used in the carnitine shuttle system to allow mitochondria to transport fatty acids into the matrix for beta-oxidation and thus production of energy from the resulting acetyl-CoA. This can also lead to an excess of Ac-CoA which can be put into gluconeogenesis (the synthesis of glucose from non-sugar precursors). Because the brain and neurons use glucose as their exclusive fuel (unless you go ketotic, in which case they can use ketone bodies such as acetoacetyl-CoA), this helps improve brain function. In theory, at least. It seems likely though.
Acetly-L-Tyrosine can be used as a precursor for thyroid hormones T3 and T4 (triiodo- and tetraiodothyronine), as well as epinephrine. This would serve to improve metabolism as well as brain function, as epinephrine puts your mind on a state of alert to a certain extent.
DMAE (dimethylaminoethanol) is a carrier of and acetyl moiety which can be trans-acetylated on to choline to form the neurotransmitter acetylcholine. How that improves nerve/brain function should be relatively obvious...
I don't know if anyone cares, but I like getting these side-notes in. When you guys talk gear and cycles, I feel like the noob (which I am, to an extent)... but when you guys talk biochemistry, well, that's the area in which I'm doing my doctoral studies at present.
Regards,
-M