I have both ME/CFS brain fog and ADHD caused by meningitis, so reading is now difficult, and I find everything confusing!
I bought some phenylpiracetam, and tried doses up to 100 mg, and although it made me feel a bit more alert and clear minded, and boosted motivation, I also felt a little flatter in terms of my emotions. However, I do suffer from anhedonia and blunted affect (emotional flatness) anyway, so I am prone to this.
Piracetam I find has similar cognitive benefits, but produces far stronger levels of anhedonia and blunted affect, so I rarely use piracetam nowadays (but I successfully used piracetam for many years before getting ME/CFS).
However, I don't think this blunted affect side effect will occur in other ME/CFS patients trying phenylpiracetam, unless you suffer from blunted affect to start with.
The interesting thing I found with phenylpiracetam is that even on just a 50 mg dose, its cognitive and motivational benefits seem to last well into the next day.
Whereas I find piracetam wears off after half a day or so, and I find aniracetam wears off after just 2 or 3 hours.
Noopept 30 mg tends to work best for me, though technically this is not a drug of the racetam class.