I don't remember everything I took, it was many years ago, but at one point or another I'm pretty sure I tried every single racetam. And a bunch of other things.

My intuitive sense is that things that over clock your brain such as racetams have negative long term effects if continuously taken. If you only take it to study for a specific test, or solve a specific problem, that's a different story.

While other things such as acetylcholine and L-Tyrosine found abundantly in our food sources are utilized effectively by the body and brain without significant long term damage. However because our bodies evolved to effectively utilize compounds coming in as clusters in our natural food sources, that's reason to believe there's a significant probability that it would be better for our health as well as cognitive performance if we get these compounds by eating whole foods such as eggs and liver.

But I'm not a doctor. Do your own research. After getting head aches that lasted for years and years, with a large portion of my brain feeling like there was a block of cement in it and in pain, I researched online and found a forum full of around a hundred or so people who all had the same symptoms from racetams I believe it was. This was like, 10 years ago, so I wouldn't be able to find the forum.