I have often recommended Piracetam for cognitive issues. I have personally observed dramatic improvement within minutes in others, and observed it with myself. Unfortunately in the US it is not directly available because of FDA rulings (the same situation as for Mutaflor — E.Coli Nissle 1917 probiotic). Mutaflor is well documented (citations) with over 240 studies, and safely used in Europe for over a century — and works far better than any probiotic approved by the FDA.
Today, when I mentioned it, a facebook user wrote “Piracetam seems to come with warnings:” and linked to a JAMA article from 2019.
Our findings demonstrate that even after the FDA rejected an application to market piracetam as a new supplement ingredient,3 the drug was nevertheless introduced into the marketplace. Despite FDA warning letters,6 the products remain on the market. Until the law governing supplements is reformed such that products adulterated with drugs can be effectively removed from the market, clinicians should advise patients that supplements marketed as cognitive enhancers may contain prohibited drugs at supratherapeutic doses.
This was not a warning of the dangers of this substance — but a warning of the sale of a substance direct to retail as a supplement ignoring FDA rulings in some products (which seems like a very American attitude 🙂 )
Originally marketed by UCB Pharma in 1971, piracetam was the first nootropic drug to modulate cognitive function without causing sedation or stimulation 1. It is not approved for any medical or dietary use by the FDA. In the UK, piracetam is prescribed mainly for myoclonus, but is used off-label for other conditions such as learning difficulties in children, memory loss or other cognitive defects in the elderly, and sickle-cell vaso-occlusive crises 4. Evidence to support its use for many conditions is unclear.Piracetam, DrugBank
What is known from studies
Checking PubMed, I found over 3700 studies on it! You do not get that volume of studies from something that does nothing. A few randome studies:
- The potential for one drug, administered at the earliest preclinical stage, to prevent the subsequent decline of cognition that eventuates in dementia  ” Each of four drugs, … minocycline, and piracetam, benefits synaptic impairment. “
- “Piracetam, a nootropic drug that has been clinically used for decades but remains enigmatic due to no distinct understanding of its mechanism of action. …. Piracetam treatment offered significant protection against LPS induced oxidative and inflammatory parameters and inhibited astrocytes activation. ” 
- Piracetam attenuates binge eating disorder related symptoms in rats 
- Piracetam inhibits ethanol (EtOH)-induced memory deficit by mediating multiple pathways 
- Piracetam prevents memory deficit induced by postnatal propofol exposure in mice 
The JAMA was concerned about supratherapeutic doses, i.e. above 1500 mg. Going over to DrugBank Pharmacology resource we read
The cases of overdose with piracetam is rare. The highest reported overdose with piracetam was oral intake of 75g which was associated with diarrhea and abdominal pain; the signs were most likely related to the extreme high dose of sorbitol contained in the used formulation
I suspect that the FDA ruling for piracetam is similar to that for Mutaflor. The decision was influenced by established american industries with a vested interest in selling their existing (ineffective often) products.