The most annoying thing about pieces like this is how easy it would be to actually test the hypothesis. They could just give people choline (double blind placebo including some participants who are not anxious). And test the effect on both choline levels and anxiety.
It’s also ready sold OTC.
Instead people just sit around and do meta studies on meta studies on correlation and publishing whatever statistical anomalies they can find.
Trials are really different skill set compared to the scanning for these chemicals or in this case meta studying. Trials involve large numbers of people you have determined do and do not have the condition you are trying to treat and then having your treatment and having some way to measure if the treatment is impacting the thing you expect it to (brain choline levels) and whether that impacts the symptoms (anxiety).
Trials cost millions and in this case would require a number of different expertise, meta studies on the other hand is just reading and statistical analysis with knowledge of the biases of papers and assessing them critically and they don't cost millions.
This is how research works. Someone, somewhere, someday will see this study and do just that. Or it could be the next step for the researchers at UC Davis who published this.
Anecdotal, but I've had life long issues with anxiety. First time hearing about choline, but about a year ago I started taking omega 3 capsules on a whim, and its been a game changer. Eating salmon as they suggest has a similar positive effect. YMMV.
I can understand why this may seem simple, but when it comes to the brain almost nothing is simple.
Choline a key component in Acetylcholine is the primary neurotransmitter used in your hippocampus. Its an excitatory neurotransmitter meaning it turns neurons on. The hippocampus is a massive parallel feedback circuit that when over stimulated can and will begin to seize. In fact many people who suffer from seizures have over active hippocampal circuitry. Simply "flooding" the brain with more choline could have very very bad effects.
Likewise, taking choline might not work as the brain actively controls and regulates the contents of the cerebral spinal fluid. Unlike the rest of your body, the capillaries in the brain are not leaky, but instead are enshrouded in the blood-brain barrier and there are active transport proteins for anything that isn't lipid soluble.
Choline is actively transported into the brain and the brain has additional internal mechanisms to regulate the levels of choline.
Lastly, neurotransmitters aren't just floating around in the soup of your brain. They are released by specific neurons which are integrated into specific circuits. Parkinson's disease is a perfect example here. There is tiny region of the brain involved in regulating voluntary movements that is rich in dopamine neurons. For Parkinson's these neurons die off while the rest of the brain remains relatively strong. Simply putting dopamine into the brain doesn't fix the issue you need to up the dopamine released by these specific neurons.
The treatment here is l-dopa which is a precursor to dopamine which does this, but once those neurons are gone they're gone and there is little we can do to stop the disease.
So if this works for l-dopa why won't it work for choline? My guess is because of the tight regulation the brain has around choline levels as its needed to prevent the hippocampus from seizing up.