I think "acetylcholine deficiency" is probably nonsense. Talking about
the brain in terms of deficiencies or excesses of particular
neurotransmitters is like talking about a photograph in terms of how
much red, green and blue it has. Sure, sometimes the color balance can
be off, but usually what makes a photo work isn't the amount of color,
but the patterns in which they're displayed. "Acetylcholine deficiency"
as a syndrome seems to be mostly the invention of some layman on
longecity.com with mediocre neuroscience knowledge. The enzymes that
create and break down acetylcholine are quite fast and are unlikely to
be deficient. As a neurotransmitter, acetylcholine is recycled with high
efficiency and speed. Choline (without the acetyl) is used in several
other roles, including the construction of cell membranes, and those
roles are more likely to suffer from dietary choline deficiency than the
neurotransmitter role.
If you found that your memory got worse while taking piracetam and
lecithin, then I suggest you stop taking one or both of them. (I think
lecithin probably doesn't do anything.) The research on piracetam
suggests that, on average, it helps verbal working memory and verbal
long term memory. However, if a drug improves performance for 25% of
people by +2 units and worsens performance for 25% of people by -1
units, it still helps on average.
Jonathan